The drug effects questionnaire: psychometric support across three drug types

Inter-individual divergence in thresholds for detecting opioid effects: Within-subject human laboratory evidence of a testable behavioral phenotype

Variations in inter-individual response to opioid medications has not been well-investigated in prospective, empirical designs or in persons who have no learned experience with opioids or current pain conditions. These analyses categorized response to opioids during rigorous human laboratory experimental conditions. Healthy individuals (N = 75) with little to no prior opioid exposure completed a 5-day residential study wherein they received triple-blinded doses of placebo or oral hydromorphone (2mg, 4mg, 8mg). Outcomes included a series of general and specific visual analog scale (VAS) ratings completed by participants and blinded observers, physiological endpoints, and analgesic responses to laboratory-evoked pain. The lowest dose at which participants endorsed > 20 point change in self-reported "Drug Effect" VAS ratings from baseline was used to define the following opioid sensitivity thresholds: 2mg ("Low Threshold", N = 9), 4mg ("Medium"; N = 29), and 8mg ("High", N = 14); a "No Threshold" group (N = 31) did not endorse any effects at any dose. Main effects of sensitivity threshold existed for most participant-reported responses and conformed to threshold categories in dose-dependent ways. In contrast, no main effects of sensitivity threshold were observed for blinded observer ratings, physiological endpoints, or evoked analgesic responses, such that hydromorphone produced dose-dependent opioid agonist effects for all participants that diverged from their self-reported experience. These data provide the most granular assessment of inter-individual differences in opioid response among persons with little or no lifetime opioid exposure or existing pain condition. All participants experienced dose-dependent changes in opioid agonist responses, yet their self-awareness of these effects varied and 30 % of participants endorsed no awareness of opioid exposure at any dose. These data demonstrate a consistent and reliable divergence between the subjective experience of opioids from rigorously-assessed physiological, observable, and analgesic responses. Testable implications of these outcomes are discussed.

Across the spectrum: Acute alcohol responses in young adults with mild, moderate, and severe alcohol use disorder

BACKGROUND

Little is known about acute subjective and physiological responses to alcohol in individuals with alcohol use disorder (AUD), particularly as it pertains to the spectrum of AUD severity. This study examined acute biphasic alcohol response phenotypes in participants with mild, moderate, and severe AUD.

METHODS

Study data was from the third cohort of the Chicago Social Drinking Project (N = 101, 50 % male; M age=27.1 years). AUD severity was determined based on the DSM-5; 20 % of participants had mild, 20 % had moderate, and 60 % had severe AUD. In a random-order, within-subject, oral alcohol administration paradigm, participants received a high alcohol dose (0.8g/kg), a very high alcohol dose (1.2g/kg), and placebo in separate sessions. Breath alcohol concentration (BrAC), subjective responses (liking, wanting, stimulation, and sedation), and cortisol levels were measured.

RESULTS

Analyses revealed that, relative to those with mild AUD, both very high and high alcohol doses (vs. placebo) significantly increased liking, wanting, and stimulation in the severe AUD subgroup, with a dose-response relationship (very high dose > high dose > placebo) in the moderate AUD subgroup. Alcohol produced lower sedation in participants with moderate and severe AUD relative to mild AUD, suggestive of tolerance to alcohol's sedating and fatiguing effects. Cortisol response to alcohol did not differ across groups, except for higher baseline levels in the severe AUD subgroup, which carried forward.

CONCLUSIONS

Taken together, these findings indicate that higher AUD severity is associated with enhanced sensitivity to alcohol's positive effects, challenging traditional notions of global alcohol tolerance and reward deficit in people who drink excessively.

Effects of methamphetamine on two measures of reward: Euphoria and neural activation to reward cues

Stimulants enhance dopamine function, affecting diverse aspects of reward function from neural processing of reward cues to feelings of well-being in humans. However, little is known about the relationships among different measures of reward function. Understanding relationships among different indices of reward processing could provide insight into the processes that control motivated behavior. The present study examined the effects of a single dose of methamphetamine on two measures of reward in healthy adults: feelings of well-being and neural activation with reward-related stimuli. In a randomized, within-subject, double-blind study, 88 healthy men and women received a single 20 mg oral dose of methamphetamine (MA) and placebo, across two sessions. Regional activations to reward-related cues were assessed using fMRI during the Monetary Incentive Delay task, and positive subjective effects of MA were assessed using standardized questionnaires. As expected, MA increased euphoria and feelings of well-being. MA had minimal effects on neural activation during either anticipation or receipt of reward, but it significantly increased ventral striatal activation during anticipation of monetary loss, suggesting heightened salience of loss-related cues. As reported previously, caudate activation during reward anticipation during the non-drug (placebo) session was correlated with euphoria induced by MA (on the MA session). However, this correlation between cue-induced neural activation and euphoria was not apparent on the MA session. Thus, MA-induced euphoria was related to reward cue-elicited neural activation only when participants were tested without the drug. MA increased neural reactivity to loss, and this was not correlated with euphoria. These findings suggest that MA can dampen reward-related neural activity normally detected in the drug-free state, and that it enhances brain responses to loss. Further research is needed to determine how neural responses to reward or loss cues are related to feelings of well-being, and how either of these affect reward-related behavior.

Behavioral Effects of Stimulated Dopamine Release and D2-like Receptor Displacement in Parkinson's Patients with Impulse-Control Disorder

Dysregulated dopamine (DA) release in the mesocorticolimbic circuit is noted in Parkinson's disease (PD) patients with impulsive and compulsive behaviors (ICBs). However, the effect of acute DA release on mood, the localization of this process, and the phenotypic differences in patients with ICB remain unknown. We applied a placebo-controlled dextro-amphetamine (dAMPH) study in 20 PD patients: 10 with ICBs (PD-ICB) and 10 without (PD-C). Subjective mood experiences were measured with well-described self-reported measures including the Positive and Negative Affect Scale (PANAS), Drug Effects Questionnaire (DEQ), and Amphetamine Interview Rating Scale (AIRS). D2-like receptor availability was measured as non-displaceable binding potential (BPND) using PET imaging with the high-affinity D2/3 receptor ligand [18F]-fallypride. Among all the subjects, dAMPH increased the PANAS positive, DEQ feel, DEQ high, and AIRS total scores. Increases in the PANAS positive and AIRS total scores were greater in the PD-ICB cohort. A mixed-effects model correlated these questionnaire changes with dAMPH-induced reductions in BPND in the ventral striatum (VS), caudate, amygdala, and caudo-medial orbitofrontal cortex. The baseline caudate, VS, and amygdala BPND positively correlated with lower on-dAMPH PANAS positive scores. Elevated mood symptoms of acute dAMPH administration in PD are linked to DA release in the mesocorticolimbic regions. Distinctions in behavioral effects among PD-ICB subjects emphasize that dysregulated striatal and extra-striatal DA-ergic networks alter mood responses to stimulated DA release and may also contribute to behavioral changes resulting from DA-targeting therapies in PD.

Nucleus accumbens functional connectivity changes underlying alcohol expectancies in bipolar disorder and prospective alcohol outcomes: a within-subject randomized placebo-controlled alcohol administration fMRI study

Introduction

Alcohol use disorder (AUD) occurs at higher rates in individuals with bipolar disorder compared to the general population. A paucity of data are available on specific mechanisms that may contribute to bipolar and AUD co-occurrence. We recently reported differences in alcohol expectancies and placebo response during alcohol administration in early-stage bipolar disorder, compared to healthy young adults. This current report investigated subjective and neural response following placebo beverage consumption in young adults with bipolar disorder.

Methods

As part of a within-subject placebo-controlled alcohol administration study, 54 young adults (53% with bipolar disorder type I, age mean + SD = 23 + 2 years, 64% female) completed resting state functional MRI (rsfMRI) scans at baseline (pre-beverage) and following placebo and alcohol consumption (counter-balanced). Participants completed subjective response measures during placebo and alcohol beverage conditions. Between-group differences in subjective response and placebo-related changes in functional connectivity of the Nucleus Accumbens (NAc) with other brain regions, compared to a pre-beverage rsfMRI baseline condition, were investigated. Fisher-transformed correlation coefficients between ROIs and seed-to-clusters showing a significant group-by-condition (placebo, pre-beverage rsfMRI) interaction were calculated. Associations with prospective alcohol use and problems were explored in a subgroup with longitudinal data.

Results

Young adults with bipolar disorder reported greater intoxication during the placebo condition, compared to healthy young adults (main effects of group: p < 0.05). Compared to pre-beverage rsfMRI, the placebo condition related to increased connectivity between bilateral NAc and regions within the sensorimotor network in bipolar disorder. Comparison participants showed the opposite pattern of placebo-related changes in connectivity (group-by-condition, p-FDR < 0.05). Greater anxiolytic effects endorsed during placebo and associated increases in NAc functional connectivity related to greater alcohol use and alcohol problems at follow-up in bipolar disorder (p < 0.05).

Discussion

Results suggest differences in placebo response in bipolar disorder, including distinct neural correlates, that may relate to prospective alcohol use/problems. Given the theoretical association between placebo response and self-reported alcohol expectancies, findings could open the door to interventions aimed at changing expectancies.

Switching from menthol to non-menthol cigarettes does not impact acute responses to intravenous nicotine

BACKGROUND

Limited research exists on how switching from menthol to non-menthol cigarettes affects the acute response to nicotine for individuals who smoke menthol cigarettes. Such research can inform public health strategies to reduce smoking prevalence.

AIMS

This study investigated whether switching from menthol to non-menthol cigarettes for two weeks alters the acute responses to intravenous nicotine infusions delivered at different rates. We assessed changes in subjective drug effects, smoking urges, withdrawal severity, heart rate, and performance on the Continuous Performance Test (CPT) (primary outcomes); as well as nicotine biomarker blood levels (ng/ml) of nicotine, cotinine, and nicotine metabolite ratio (NMR; hydroxycotinine/cotinine), and cigarette consumption (secondary outcomes).

METHODS

Sixteen menthol-preferring individuals who smoke cigarettes were randomized to a sequence of menthol or non-menthol cigarette smoking conditions for 2 weeks (Phase 1) and then switched to the other condition for another 2 weeks (Phase 2). During week 2 of each phase, an experimental session was held. During the experimental sessions, participants were given a total of 3 infusions, one saline and two nicotine infusions delivered at different rates (1 mg nicotine delivered over 2.5- and 5-min). Each infusion period lasted 10 min, with saline administered for the remainder of the time after the 2.5- and 5-min nicotine infusions. Following the first session, participants crossed over to the other smoking condition.

RESULTS

Switching to non-menthol cigarettes led to a decrease in daily cigarette smoking (p < .05). However, this switch did not appear to affect the severity of tobacco withdrawal, urges to smoke, or the subjective and heart rate responses to IV nicotine administration (p > .05).

CONCLUSIONS

These findings suggest that switching from menthol to non-menthol cigarettes is feasible without significantly altering the individual's response to nicotine. Further, there may be a potential public health benefit through reduced cigarette consumption.

Methamphetamine-induced adaptation of learning rate dynamics depend on baseline performance

The ability to calibrate learning according to new information is a fundamental component of an organism's ability to adapt to changing conditions. Yet, the exact neural mechanisms guiding dynamic learning rate adjustments remain unclear. Catecholamines appear to play a critical role in adjusting the degree to which we use new information over time, but individuals vary widely in the manner in which they adjust to changes. Here, we studied the effects of a low dose of methamphetamine (MA), and individual differences in these effects, on probabilistic reversal learning dynamics in a within-subject, double-blind, randomized design. Participants first completed a reversal learning task during a drug-free baseline session to provide a measure of baseline performance. Then they completed the task during two sessions, one with MA (20 mg oral) and one with placebo (PL). First, we showed that, relative to PL, MA modulates the ability to dynamically adjust learning from prediction errors. Second, this effect was more pronounced in participants who performed moderately low at baseline. These results present novel evidence for the involvement of catecholaminergic transmission on learning flexibility and highlights that baseline performance modulates the effect of the drug.

Immediate effects of propofol on mood: a randomized comparison of two doses in a cohort with depression

RATIONALE

The intravenous anesthetic propofol is known to induce positive mood effects during routine clinical use, suggesting it might be repurposed as an antidepressant, but also raising concerns about abuse potential. How propofol's acute effects vary by dose and with repeated infusions is unknown.

OBJECTIVES

This exploratory analysis aimed to (1) compare the immediate mood effects of propofol administered at two different doses, (2) describe how those mood effects change with repeated infusions, and (3) evaluate whether acute mood improvement predicts later antidepressant response.

METHODS

Twenty-four adults with moderate-to-severe treatment-resistant depression were randomized into two dosing groups. Six low- or high-dose propofol infusions were administered under blinded conditions over a two-week period. Self-reported mood states were recorded before and after each infusion using the Positive and Negative Affect Schedule (PANAS-X). Abuse potential was evaluated with the Drug Effects Questionnaire (DEQ-5).

RESULTS

At the first infusion, propofol induced acute improvements in PANAS-X Sadness, Fear, Joviality, and Serenity scales (p < 0.002), independent of dose. Over the series of six infusions, acute changes in Sadness, Fear, and Joviality, but not Serenity, diminished with infusion number (p < 0.002). The DEQ-5 "want more" rating decreased across infusions (p = 0.002). Changes in PANAS-X scales with the first infusion did not predict later improvement in depression severity (p > 0.05).

CONCLUSION

Cumulative changes in mood states observed with repeated infusions suggest that propofol engages adaptive mechanisms in mood circuitry. Subjective responses with repeated infusions do not indicate increasing potential for abuse in this patient population.

Alcohol increases social engagement in dyadic interactions: role of partner's drug state

RATIONALE

Alcohol is commonly used in social environments and is known to facilitate social behaviors. However, most controlled laboratory studies on alcohol have been conducted in isolated settings, limiting our understanding of its effects on social interactions.

OBJECTIVES

The current study was designed to examine the effects of alcohol on dyadic interactions in healthy volunteers (N = 37), with a focus on the influence of the conversation partner's drug state.

METHODS

Using a 4-session, placebo-controlled, within-subjects design, participants received a moderate dose of alcohol (0.8 g/kg men) or placebo in randomized order before engaging in a 45-minute semi-structured conversation with a partner who received either alcohol or placebo. Partners were always strangers. Outcome measures included subjective responses to alcohol, self-reported closeness to partners, and facial expressions during interactions analyzed via a machine learning model.

RESULTS

Alcohol produced its expected subjective effects, some of which were enhanced when the partner also received alcohol. Alcohol enhanced enjoyment of social interactions and feelings of connectedness, irrespective of the partner's drug condition. Facial expression analysis revealed that alcohol increased positive and decreased negative emotional expressions. For women but not men, these effects were more pronounced when their conversation partners also received alcohol. Individual emotion analysis revealed that alcohol increased the intensity of facial expressions associated with amusement, joy, and excitement, while reducing emotions such as awkwardness and contempt.

CONCLUSIONS

Our findings show that alcohol increases feelings of social connectedness, and that responses to alcohol can be influenced by the drug state of interacting partners. The increased feelings of social connection may contribute to risk for escalation of use.

Pace of alcohol drinking during in natural-environment drinking is associated with heightened alcohol-related reward and negative consequences in risky drinkers

BACKGROUND

Sensitivity to alcohol's stimulating and rewarding properties is associated with increased risk for future heavy drinking and the development and maintenance of alcohol use disorder (AUD). Further, pace of alcohol consumption varies across individuals and affects level of intoxication and subjective alcohol responses. The present study used smartphone-based high-resolution ecological momentary assessment (HR-EMA) of a heavy drinking episode in young adult risky drinkers' natural environments to examine associations between pace of drinking and subjective responses to alcohol.

METHOD

Young adult risky drinkers (N = 248; 42% female) completed a 3-hour HR-EMA of alcohol use and subjective responses to alcohol (stimulation, sedation, feeling, liking, and wanting more) during a drinking episode in their natural environment. Analyses examined associations between drinking pace trajectories and subjective responses to alcohol, accounting for drinking context (location/presence of others) and depression.

RESULTS

Trajectory analysis revealed three drinking pace subgroups based on total drinks consumed during the 3-hour monitoring period: fast risers (~ 4 standard drinks/hour), moderate risers (~ 2.6 standard drinks/hour), and slow risers (~ 1.4 standard drinks/hour). Overall, faster pace of drinking was associated with greater alcohol stimulation and reward (liking and wanting more) and more alcohol-related negative consequences during and after the episode.

CONCLUSIONS

Results further underscore the heterogeneous nature of young adult risky drinkers and suggest the possibility that these individuals may drink rapidly to experience the stimulating and rewarding effects of alcohol sooner. Resulting increases in the positive effects of alcohol may reinforce future rapid drinking behavior.

Real-Time Assessment of Alcohol Reward, Stimulation, and Negative Affect in Individuals With and Without Alcohol Use Disorder and Depressive Disorders

OBJECTIVE

The allostasis theory states that, as addiction develops, alcohol is consumed to relieve negative affect rather than to produce positive effects. This study aimed to investigate the real-time subjective effects of alcohol in individuals with alcohol use disorder (AUD) and those prone to negative affect by virtue of having comorbid depressive disorder (DEP).

METHODS

Participants (N=221) completed high-resolution ecological momentary assessments during 3-hour monitoring of one alcohol drinking episode and one non-alcohol drinking episode in their natural environment. Participants also completed daily mood surveys and next-day surveys. Linear mixed-effect models were used to compare drinking behavior and subjective responses (stimulation, sedation, liking, wanting, negative affect) among 120 participants with AUD (AUD+; with depression [DEP+]: N=64, without depression [DEP-]: N=56) and 101 participants without AUD (AUD-; DEP+: N=45, DEP-: N=56).

RESULTS

During the monitoring period, participants with AUD consumed an average of 8.5 standard alcohol drinks (estimated blood alcohol concentration [eBAC]=0.115 g/dl) versus 3.7 drinks (eBAC=0.040 g/dl) for non-AUD participants. The AUD group, regardless of comorbid DEP, reported increases in stimulation and rewarding effects that persisted throughout most of the alcohol episode relative to the non-alcohol episode. To a lesser extent, alcohol relieved negative affect but this was not specific to AUD or DEP groups.

CONCLUSIONS

Contrary to the allostasis model of addiction's emphasis on negative reinforcement drinking, findings demonstrated that people with AUD prone to negative affect displayed positive alcohol reinforcement with pronounced and prolonged sensitivity to alcohol's pleasurable effects, akin to their noncomorbid counterparts. The findings provided critical testing of addiction theories in the natural environment to enhance external validity.

Dexmedetomidine HCL (BXCL501) as a potential treatment for alcohol use disorder and comorbid PTSD: A phase 1b, placebo-controlled crossover laboratory study

BACKGROUND AND OBJECTIVES

Noradrenergic dysregulation is important in the pathophysiology of posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD); pharmacotherapies targeting adrenergic function have potential as treatment for comorbidity. Dexmedetomidine (sublingual film formulation-BXCL501; IGALMI) is a highly potent, selective ⍺2-adrenergic receptor agonist and may be superior to other pharmacotherapeutic approaches. A within subjects, phase 1b safety laboratory study was conducted to evaluate adverse effects of BXCL501 when combined with alcohol; BXCL501's potential efficacy was also explored.

METHODS

Heavy drinker participants with a diagnosis of or who were at risk for PTSD participated in three separate test days which included pretreatment with BXCL501 (40 µg, 80 µg or placebo) administered in a randomized, double-blind fashion, followed by three testing conditions: alcohol cue reactivity, trauma-induced reactivity, and IV ethanol administration. Safety outcomes included blood pressure (BP) and sedation. Exploratory outcomes included alcohol craving, trauma-induced anxiety and craving and subjective effects of alcohol.

RESULTS

Ten of twelve randomized participants competed the entire study. BXCL501 (80 µg) was associated with expected mild changes in BP and sedation; administration with alcohol did not affect those parameters. There were no clinically significant adverse effects. BXCL501 attenuated trauma-induced anxiety and attenuated subjective effects of alcohol.

DISCUSSIONS AND CONCLUSIONS

BXCL501 is safe for use in humans who may drink alcohol while undergoing treatment. BXCL501 may be explored as a potential treatment for PTSD and AUD.

SCIENTIFIC SIGNIFICANCE

This is the first study to provide scientific support for BXCL501's potential to treat PTSD and comorbid AUD.

Real-time mechanism-based interventions for daily alcohol challenges: Protocol for ecological momentary assessment and intervention

Background

Advancing evidence-based, tailored interventions for substance use disorders (SUDs) requires understanding temporal directionality while upholding ecological validity. Previous studies identified loneliness and craving as pivotal factors associated with alcohol consumption, yet the precise directionality of these relationships remains ambiguous.

Objective

This study aims to establish a smartphone-based real-life intervention platform that integrates momentary assessment and intervention into everyday life. The platform will explore the temporal directionality of contextual influences on alcohol use among individuals experiencing loneliness and craving.

Methods

We will target 180 individuals aged 18 to 70 in Germany who report loneliness, alcohol cravings, and meet risk or binge drinking criteria (over 14 standard drinks per week or five drinks in a single day for males, and over seven drinks per week or four drinks in a single day for females). Using a Within-Person-Encouragement-Design and Just-In-Time-Adaptive-Interventions, we will manipulate the contexts of loneliness and alcohol craving with cognitive reappraisal and physical activity interventions against a control condition (working memory task).

Results

Recruitment started in June 2024, with data collection and processing expected by June 2027.

Conclusion

Our real-life intervention platform endeavors to serve as a robust tool for discerning the directionality of the effects from time series data in everyday life influences on alcohol use for the future study. Ultimately, it will pave the way for low-threshold prevention, clinical treatment, and therapy to target diverse contexts of everyday life in SUD.

Trial registration

German Clinical Trials Register DRKS00033133.

An exploratory study of the safety profile and neurocognitive function after single doses of mitragynine in humans

RATIONALE

Despite the growing scientific interest on mitragynine, the primary alkaloid in kratom (Mitragyna Speciosa), there is a lack of clinical trials in humans.

OBJECTIVES

This phase 1 study aimed to evaluate mitragynine's safety profile and acute effects on subjective drug experience, neurocognition, and pain tolerance.

METHODS

A placebo-controlled, single-blind, within-subjects study was conducted in two parts. In part A, eight healthy human volunteers received placebo and three doses of mitragynine (5, 10, and 20 mg) in a sequential dosing scheme, on separate days. In part B, a second group of seven volunteers received placebo and 40 mg of mitragynine. Vital signs, subjective drug experience, neurocognitive function, and pain tolerance were measured at regular intervals for 7 h after administration.

RESULTS

Overall, mitragynine did not affect most of the outcome measures at any dose. Yet, the lowest dose (5 mg) of mitragynine increased subjective ratings of arousal and attention, accuracy in a sustained attention task, and motor inhibition. The highest dose (40 mg) of mitragynine increased subjective ratings of amnesia and produced mild psychopathological symptoms. Mitragynine did not significantly affect vital signs, and only mild, transient side effects were reported.

CONCLUSION

The present study suggests that low doses (5-10 mg) of mitragynine may cause subjective feelings of stimulation and enhance attention, while the highest dose (40 mg) may cause inhibitory feelings of amnesia and distress. Mitragynine doses up to 40 mg were well tolerated in this group.

Lisdexamfetamine in the treatment of methamphetamine dependence: A randomised, placebo-controlled trial

AIMS

This study tested the efficacy and safety of a 12-week course of lisdexamfetamine in reducing methamphetamine use, an outcome which is associated with improvements in health and wellbeing, in people dependent on methamphetamine.

DESIGN, SETTING AND PARTICIPANTS

This study was a randomised double-blind placebo-controlled trial conducted in six specialist outpatient clinics in Adelaide, Melbourne, Newcastle and Sydney, Australia (2018-2021). Participants were164 adults with methamphetamine dependence, reporting at least 14 use days out of the previous 28 days (62% male, 38% female, < 1% other; mean age 39 years).

INTERVENTIONS

Participants were randomly allocated 1:1 to a 15-week regimen of lisdexamfetamine (1-week induction to 250 mg, 12-week maintenance regimen, 2-week reduction; n = 80) or matched placebo (n = 84), followed-up to Week 19.

MEASUREMENTS

The primary efficacy measure was past 28-day methamphetamine use at Week 13. Safety was assessed by adverse event rates. Secondary measures included methamphetamine use during the 12-week treatment period and treatment satisfaction.

FINDINGS

Nine randomized participants did not start treatment (five were allocated to lisdexamfetamine and four allocated to placebo) and were excluded from the analyses. Fifty-seven per cent of participants were retained on study medication to primary end-point. There was only weak evidence of a lisdexamfetamine benefit at 13 weeks [adjusted difference in days of methamphetamine use = 2.2, 95% confidence interval (CI) = -0.5 to 5.0; P = 0.49]. However, throughout the whole 12-week treatment maintenance phase, the lisdexamfetamine group had fewer days of methamphetamine use in total (difference = 8.8, 95% CI = 2.7-15.0; P = 0.005). The lisdexamfetamine group reported greater self-reported treatment effectiveness [odds ratio (OR) = 2.89, 95% CI = 1.67-5.02; P < 0.001] and treatment satisfaction (OR = 3.80, 95% CI = 1.93-7.47; P < 0.001). Adverse events with lisdexamfetamine included nausea. Serious adverse events occurred in four (5%) of participants who received lisdexamfetamine.

CONCLUSIONS

Lisdexamfetamine appears to reduce methamphetamine use over a 12-week treatment period, although there is only weak evidence that reduced use is maintained during the last 4 weeks.

Low-Dose LSD Alters Early and Late Event-Related Potentials to Emotional Faces

Introduction

Despite widespread popular interest in the use of low doses of Lysergic acid diethylamide (LSD) to improve mood, little is known about how these doses affect emotional processing in the brain. In this study, we tested the effect of a single low dose of LSD (26 µg) compared with placebo on electroencephalogram (EEG) event-related potentials (ERP: N170, P300 and Mismatch Negativity) in healthy adults, while participants viewed angry, happy, and neutral faces. We hypothesized that the drug might affect either neutral faces, which are sometimes perceived as threatening, or emotional faces.

Methods

Healthy young adults (n = 39) received LSD (26 µg or placebo sublingually) before completing an oddball task with emotional facial expressions during EEG recording. The N170 and P300 evoked potentials were recorded using EEG. LSD and placebo were administered in double-blind, randomized order separated by at least 7 days. During the oddball task, three emotional faces were presented infrequently (angry, happy, neutral) in a block design, and a cartoon face was presented frequently.

Results

LSD significantly reduced the amplitude of the occipitotemporal N170 ERP to Neutral faces, but not angry or happy faces. LSD also reduced the amplitude of the midline posterior parietal P300 ERP to neutral and happy faces, but not angry faces.

Discussion

These differential effects of LSD on the amplitude of the N170 and P300 to neutral and emotional faces add to our understanding of how low doses of LSD might affect the brain response to social and emotional information.

Event-level associations among THC, CBD, social context, and subjective effects during Cannabis use episodes

BACKGROUND

Limited research considers the quantity and potency of cannabis products along with social context on the subjective effects of real-world cannabis use.

AIMS

This study examined the subjective effects of acute use as a function of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) doses and social context during cannabis use episodes.

METHOD

Ninety-six participants (43.75% male, Mage = 35.73) reporting weekly cannabis use completed a baseline self-report battery assessing cannabis use. Then, THC and CBD potency and quantity of the cannabis product, social context, and subjective experience were assessed through self-initiated surveys after cannabis use episodes during a 14-day ecological momentary assessment (EMA).

RESULTS

Greater feeling high and liking were significantly associated with a higher THC dose than one's average (b = 0.03, p < 0.001; b = 0.02, p < 0.001) and social use (b = 0.38, p < 0.001; b = 0.20, p = 0.01). A higher CBD dose than one's average (b = 0.01, p = 0.04) was significantly associated with greater liking. A significant interaction effect of THC dose and social context (b = 0.01, p = 0.02) was observed such that solitary use had a negative association between THC dose and disliking (b = -0.01, p = 0.04), and social use had a null association (b = 0.003, p = 0.25). Individuals with greater cannabis problems reported lower liking (b = -0.18, p = 0.03) and higher disliking (b = 0.08, p = 0.02), but not feeling high, on average, across the EMA protocol.

CONCLUSION

Social context plays an important role in the subjective experience of cannabis use. Interventions targeting cannabis problems could highlight the evidence that individuals with greater cannabis problems might experience less liking but more disliking in general across use episodes to effectively challenge expectancies/motives of use.

Reprint of: Sex differences in appeal, reward, and sensory experience of E-cigarette flavors among adults who smoke cigarettes

OBJECTIVE

Flavors enhance nicotine e-cigarette appeal by altering sensory experience. Females may be more sensitive to tobacco-associated cues and uniquely affected by flavor. The current study is an exploratory analysis to examine differences by sex on reward, appeal, and sensory experience of popular e-cigarette flavors.

METHODS

Adults (N = 121) who use cigarettes (≥1 cigarette/day) were enrolled in a laboratory study in which they vaped four e-cigarette flavors (tobacco, cherry, menthol, vanilla; in separate lab sessions) in one of two freebase nicotine concentrations (6 mg/ml,18 mg/ml). Following exposures, participants rated e-cigarette reward using the Drug Effects Questionnaire (DEQ), flavor and overall e-cigarette appeal using Labeled Hedonic Scales (LHS), and intensity of flavor, irritation, coolness, fruitiness, and sweetness using Generalized Labeled Magnitude Scales (gLMS). Linear mixed models were conducted for outcomes to analyze effects of sex, flavor, and sex x flavor interaction.

RESULTS

For DEQ ratings, there was a trend (p = .08) toward a sex x flavor interaction, in which menthol flavor produced more reward than other flavors for females, but not males. For LHS ratings, there was a significant sex x flavor interaction (p = .03) for overall e-cigarette experience with females but not males rating menthol higher than other flavors. All gLMS scales but irritation showed that females generally had greater differences between flavors compared to males (ps ≤ 0.03).

CONCLUSION

Menthol in e-cigarettes may play an important role in mediating appeal and/or reward among females. This may be due in part to their ability to better detect sensory effects of e-cigarettes.

Impact of childhood adversity on acute subjective effects of stimulant and opioid drugs: Evidence from placebo-controlled studies in healthy volunteers

BACKGROUND AND AIMS

Early-life adversities are known to alter drug reward processing in rodents. Despite the well-known link between early adversity and the risk of substance use disorder, few studies have measured how childhood adversity affects human drug reward. Here, we assessed the relationship between historical childhood adversities and responses to single doses of methamphetamine, d-amphetamine or buprenorphine in healthy participants.

METHODS

Using a secondary analysis approach, we assessed the impact of childhood adversity on drug effects from three randomised, placebo-controlled studies in which healthy volunteers received methamphetamine (20 mg oral; n = 35), d-amphetamine (20 mg oral; n = 54) or buprenorphine (0.2 mg sublingual; n = 35). Ratings of feeling effect, liking, disliking, feeling high and wanting more of the drug were collected 15-210 min post-administration, and heart rate changes were analysed using random-intercept mixed-effect models. The area under the curve from these and previous studies was calculated to visualise the relationship between childhood adversity severity and drug effects.

RESULTS

Greater childhood adversity was associated with reduced feel effects (significant three-way interactions b = -0.07, 95% CI [-0.12, -0.02], p = 0.009), like effects (b = -0.07, 95% CI [-0.13, -0.00], p = 0.038) and feel high (b = -0.06, 95% CI [-0.10, -0.01], p = 0.020) towards the stimulant drugs 90-180 min post-administration.

CONCLUSIONS

Childhood adversity was not significantly associated with other subjective or heart rate responses to the drugs. Overall, participants with more childhood adversities reported dampened subjective responses to stimulant drugs, but not to buprenorphine. Future studies should examine the generalisability of these relationships, to identify the mechanisms underlying the link between childhood adversity and drug responsiveness.

Smoking-Related Increases in Alcohol Outcomes and Preliminary Evidence for the Protective Effect of a Functional Nicotine Receptor Gene (CHRNA5) Variant on Alcohol Consumption in Individuals Without Alcohol Use Disorder

BACKGROUND

Alcohol and nicotine interact with the nicotinic acetylcholine receptor system to alter reward-related responses, thereby contributing to the co-use and misuse of these drugs. A missense polymorphism rs16969968 (G>A) in the CHRNA5 gene has shown a strong association with nicotine-related phenotypes. However, less is known about the impact of this variant on alcohol-related phenotypes.

METHODS

We assessed the main and interactive effect of smoking and rs16969968 polymorphism on alcohol consumption using the Alcohol Use Disorders Identification Test (AUDIT), Timeline Follow Back (TLFB), and Lifetime Drinking History (LDH) in 980 healthy adults without alcohol use disorder. We further examined the effect of the rs16969968 polymorphism on acute alcohol consumption using a free-access i.v. alcohol self-administration (IV-ASA) human laboratory paradigm in a subset of 153 nonsmoking participants. Subjective alcohol responses, alcohol sensitivity, and expectancy measures were compared between genotype groups (GG; AA/AG).

RESULTS

We observed a significant association of smoking with AUDIT, TLFB, and LDH measures across genotype groups, with smokers showing higher scores compared with nonsmokers. Additionally, we found an association between genotype and TLFB-total drinks in the IV-ASA subset, with the GG group showing higher scores than AA/AG group. Relatedly, the alcohol negative expectancy score was significantly lower in the GG group than the AA/AG group.

CONCLUSIONS

Our findings underscore the association of smoking with alcohol measures. We found preliminary evidence for the protective effect of the functional CHRNA5 polymorphism on alcohol consumption and its association with increased negative alcohol expectancies, which highlights the substantial heterogeneity in alcohol responses.

Pulsed nicotine infusions as a model for smoking: validating a tool to explore nicotine thresholds in humans

RATIONALE

No previous studies examined the discriminative stimulus effects of intravenous (IV) nicotine in humans.

OBJECTIVES

To evaluate a pulsed IV nicotine infusion procedure designed to mimic inhaled nicotine delivery and to identify a range of nicotine doses that may capture the threshold doses for the subjective and discriminative stimulus effects of nicotine. By determining these thresholds, we can gain valuable insights into the addictive threshold of nicotine.

METHODS

Eleven participants had 2 Test Sessions following overnight abstinence from smoking. Test Session 1 examined participants' ability to discriminate 0.1 mg nicotine/pulse nicotine from saline. Test Session 2 examined if participants can discriminate 0.05, 0.025, and 0.0125 mg nicotine/pulse of nicotine from saline. These nicotine doses were delivered as a cluster of 4 pulsed-nicotine infusions of 2-second duration with a 28-second interval between each pulse.

RESULTS

The lowest doses of nicotine that produced greater responses than saline for discrimination, subjective effects, and heart rate ranged from 0.05 to 0.1 mg nicotine/pulse.

CONCLUSIONS

These findings support the validity of our pulsed-infusion procedure as a model for nicotine delivery by smoking and its utility in examining factors that may impact the addictive threshold of nicotine.

Contextual factors associated with subjective effects of cannabis: A systematic review and meta-analysis

BACKGROUND

Cannabis is consumed in various social and environmental settings, and such contexts may be important predictors of subjective effects. The aim of this systematic review and meta-analysis was to examine the relationship between contextual factors and subjective effects of cannabis.

METHODS

A PRISMA-guided search of MEDLINE, Embase, PsycINFO, Global Health, and Google Scholar yielded 29 studies.

RESULTS

Study type (Ecological Momentary Assessment or Experimental) was a significant predictor of intoxication effects, and experimental studies had a greater pooled effect size (z =.296,95 % CI [.132,.478], p=.004) than Ecological Momentary Assessment (EMA) studies (z =.071,95 % CI [.011,.130], p =.02). Contextual conditions (environment, social group, expectancy, time of day, day of week) were not significant predictors of cannabis effects.

CONCLUSION

Findings did not point to a significant association between contextual conditions and subjective effects. However, as current literature is methodologically weak, it may be premature to conclude that subjective effects are not shaped by contextual factors. In view of policy and therapeutic implications, replications and study refinements are recommended.

Sex Differences in the Safety and Subjective Effects of Two Oral Δ9-Tetrahydrocannabinol-Containing Cannabis Products over Multiple Doses Among Healthy Adults

Introduction: A growing number of females report consuming cannabis products. There is a paucity of data on sex differences in safety and subjective effects after repeated use of varying oral doses of Δ9-tetrahydrocannabinol (THC; the primary psychoactive constituent of cannabis). Materials and Methods: Data were from two randomized, double-blind, placebo-controlled, multiple-dose, between-subject trials of two THC-containing oral cannabis products. Healthy adults received placebo, low-dose THC (∼2.5 or ∼5 mg per dose), or high-dose THC (∼7.5 or ∼10 mg per dose) twice daily for 7 days. There were 38 males (8 placebo, 17 low-dose THC, 13 high-dose THC) and 46 females (8 placebo, 17 low-dose THC, 21 high-dose THC). Analyses compared adverse events (AEs) and subjective effects between males and females, by THC dose. Results: In the placebo and low-dose THC groups, there were no sex differences in the relative rate of AEs. In the high-dose THC group, females versus males reported 3.08 (95% confidence interval [CI]=1.31-8.33) times as many AEs. There were no significant interactions of sex×low-dose THC group for any subjective effect. In the high-dose THC group, females versus males reported greater "relaxed" ratings (b=15.14, 95% CI=1.44-28.84, p=0.027), whereas in the placebo group, males versus females reported greater ratings of "liking the effect" (b=-30.01, 95% CI=2.77-57.26, p=0.028). Although analyses were underpowered to assess the sex×THC dose×day interaction, the initial sex disparity in AEs and some subjective effects in the high-dose THC group appeared to shrink after the first day. Conclusions: In this exploratory analysis, sex differences in some responses to oral THC were nuanced. Females appeared more sensitive than males to AEs and some subjective effects at higher but not lower doses. Males reported higher ratings than females on some subjective effects in response to placebo. Initial sex differences in response to higher doses of oral THC tended to diminish over 7 days of dosing. If replicated, findings could help inform sex-specific dosing strategies of medical cannabis products and could help educate medical cannabis patients on any temporality of effects.

Sex differences in appeal, reward, and sensory experience of E-cigarette flavors among adults who smoke cigarettes

OBJECTIVE

Flavors enhance nicotine e-cigarette appeal by altering sensory experience. Females may be more sensitive to tobacco-associated cues and uniquely affected by flavor. The current study is an exploratory analysis to examine differences by sex on reward, appeal, and sensory experience of popular e-cigarette flavors.

METHODS

Adults (N = 121) who use cigarettes (≥1 cigarette/day) were enrolled in a laboratory study in which they vaped four e-cigarette flavors (tobacco, cherry, menthol, vanilla; in separate lab sessions) in one of two freebase nicotine concentrations (6 mg/ml,18 mg/ml). Following exposures, participants rated e-cigarette reward using the Drug Effects Questionnaire (DEQ), flavor and overall e-cigarette appeal using Labeled Hedonic Scales (LHS), and intensity of flavor, irritation, coolness, fruitiness, and sweetness using Generalized Labeled Magnitude Scales (gLMS). Linear mixed models were conducted for outcomes to analyze effects of sex, flavor, and sex x flavor interaction.

RESULTS

For DEQ ratings, there was a trend (p = .08) toward a sex x flavor interaction, in which menthol flavor produced more reward than other flavors for females, but not males. For LHS ratings, there was a significant sex x flavor interaction (p = .03) for overall e-cigarette experience with females but not males rating menthol higher than other flavors. All gLMS scales but irritation showed that females generally had greater differences between flavors compared to males (ps ≤ 0.03).

CONCLUSION

Menthol in e-cigarettes may play an important role in mediating appeal and/or reward among females. This may be due in part to their ability to better detect sensory effects of e-cigarettes.

Intoxication due to Δ9-tetrahydrocannabinol is characterized by disrupted prefrontal cortex activity

Neural states of impairment from intoxicating substances, including cannabis, are poorly understood. Cannabinoid 1 receptors, the main target of Δ9-tetrahydrocannabinol (THC), the primary intoxicating cannabinoid in cannabis, are densely localized within prefrontal cortex; therefore, prefrontal brain regions are key locations to examine brain changes that characterize acute intoxication. We conducted a double-blind, randomized, cross-over study in adults, aged 18-55 years, who use cannabis regularly, to determine the effects of acute intoxication on prefrontal cortex resting-state measures, assessed with portable functional near-infrared spectroscopy. Participants received oral THC (10-80 mg, individually dosed to overcome tolerance and achieve acute intoxication) and identical placebo, randomized for order; 185 adults were randomized and 128 completed both study days and had usable data. THC was associated with expected increases in subjective intoxication ratings (ES = 35.30, p < 0.001) and heart rate (ES = 11.15, p = 0.001). THC was associated with decreased correlations and anticorrelations in static resting-state functional connectivity within the prefrontal cortex relative to placebo, with weakest correlations and anticorrelations among those who reported greater severity of intoxication (RSFC between medial PFC-ventromedial PFC and DEQ scores, r = 0.32, p < 0.001; RSFC between bilateral mPFC and DEQ scores, r = -0.28, p = 0.001). Relative to placebo, THC was associated with increased variability (or reduced stability) in dynamic resting-state functional connectivity of the prefrontal cortex at p = 0.001, consistent across a range of window sizes. Finally, using frequency power spectrum analyses, we observed that relative to placebo, THC was associated with widespread reduced spectral power within the prefrontal cortex across the 0.073-0.1 Hz frequency range at p < 0.039. These neural features suggest a disruptive influence of THC on the neural dynamics of the prefrontal cortex and may underlie cognitive impairing effects of THC that are detectable with portable imaging. This study is registered in Clinicaltrials.gov (NCT03655717).

The effects of simultaneous alcohol and cannabis use on subjective drug effects: A narrative review across methodologies

Over 75% of young adults who use cannabis also report drinking alcohol, leading to increased risks that include impaired cognition, substance use disorders, and more heavy and frequent substance use. Studies suggest that subjective responses to either alcohol or cannabis can serve as a valuable indicator for identifying individuals at risk of prolonged substance use and use disorder. While laboratory studies show additive effects when alcohol and cannabis are used together, the impact of co-using these substances, specifically with respect to cannabidiol, on an individual's subjective experience remains unclear. This narrative review explores the effects of simultaneous alcohol and cannabis (SAM) use on subjective drug effects, drawing from qualitative research, laboratory experiments, and naturalistic studies. Experimental findings are inconsistent regarding the combined effects of alcohol and cannabis, likely influenced by factors such as dosage, method of administration, and individual substance use histories. Similarly, findings from qualitative and naturalistic studies are mixed regarding subjective drug effects following SAM use. These discrepancies may be due to recall biases, variations in assessment methods, and the measurement in real-world contexts of patterns of SAM use and related experiences. Overall, this narrative review highlights the need for more comprehensive research to understand more fully subjective drug effects of SAM use in diverse populations and settings, emphasizing the importance of frequent and nuanced assessment of SAM use and subjective responses in naturalistic settings.

The 3,4-methylenedioxymethamphetamine enhances early visual processing for salient socio-emotional stimuli

The 3,4-methylenedioxymethamphetamine (MDMA) has long been used non-medically, and it is currently under investigation for its potential therapeutic benefits. Both uses may be related to its ability to enhance empathy, sociability, emotional processing and its anxiolytic effects. However, the neural mechanisms underlying these effects, and their specificity to MDMA compared to other stimulants, are not yet fully understood. Here, using electroencephalography (EEG), we investigated the effects of MDMA and a prototypic stimulant, methamphetamine (MA), on early visual processing of socio-emotional stimuli in an oddball emotional faces paradigm. Specifically, we examined whether MDMA or MA enhance the processing of facial expressions, compared to placebo, during the early stages of visual perception. MDMA enhanced an event-related component that is sensitive to detecting faces (N170), specifically for happy and angry expressions compared to neutral faces. MA did not affect this measure, and neither drug altered other components of the response to emotional faces. These findings provide novel insights into the neural mechanisms underlying the effects of MDMA on socio-emotional processing and may have implications for the therapeutic use of MDMA in the treatment of social anxiety and other psychiatric disorders.

Neural complexity is increased after low doses of LSD, but not moderate to high doses of oral THC or methamphetamine

Neural complexity correlates with one's level of consciousness. During coma, anesthesia, and sleep, complexity is reduced. During altered states, including after lysergic acid diethylamide (LSD), complexity is increased. In the present analysis, we examined whether low doses of LSD (13 and 26 µg) were sufficient to increase neural complexity in the absence of altered states of consciousness. In addition, neural complexity was assessed after doses of two other drugs that significantly altered consciousness and mood: delta-9-tetrahydrocannabinol (THC; 7.5 and 15 mg) and methamphetamine (MA; 10 and 20 mg). In three separate studies (N = 73; 21, LSD; 23, THC; 29, MA), healthy volunteers received placebo or drug in a within-subjects design over three laboratory visits. During anticipated peak drug effects, resting state electroencephalography (EEG) recorded Limpel-Ziv complexity and spectral power. LSD, but not THC or MA, dose-dependently increased neural complexity. LSD also reduced delta and theta power. THC reduced, and MA increased, alpha power, primarily in frontal regions. Neural complexity was not associated with any subjective drug effect; however, LSD-induced reductions in delta and theta were associated with elation, and THC-induced reductions in alpha were associated with altered states. These data inform relationships between neural complexity, spectral power, and subjective states, demonstrating that increased neural complexity is not necessary or sufficient for altered states of consciousness. Future studies should address whether greater complexity after low doses of LSD is related to cognitive, behavioral, or therapeutic outcomes, and further examine the role of alpha desynchronization in mediating altered states of consciousness.

Greater subjective effects of a low dose of LSD in participants with depressed mood

Recent studies and anecdotal reports suggest that psychedelics can improve mood states, even at low doses. However, few placebo-controlled studies have examined the acute effects of low doses of LSD in individuals with psychiatric symptoms. In the current study, we examined the acute and sub-acute effect of a low dose of LSD (26 µg) on subjective effects and mood in volunteers with mild depressed mood. The study used a randomized, double-blind, crossover design to compare the effects of LSD in two groups of adults: participants who scored high (≥17; n = 20) or low (<17; n = 19) on the Beck Depression-II inventory (BDI) at screening. Participants received a single low dose of LSD (26 µg) and placebo during two 5-h laboratory sessions, separated by at least one week. Subjective, physiological, and mood measures were assessed at regular intervals throughout the sessions, and behavioral measures of creativity and emotion recognition were obtained at expected peak effect. BDI depression scores and mood ratings were assessed 48-h after each session. Relative to placebo, LSD (26 µg) produced expected, mild physiological and subjective effects on several measures in both groups. However, the high BDI group reported significantly greater drug effects on several indices of acute effects, including ratings of vigor, elation, and affectively positive scales of a measure of psychedelic effects (5D-ASC). The high BDI group also reported a greater decline in BDI depression scores 48-h after LSD, compared to placebo. These findings suggest that an acute low dose of LSD (26 µg) elicits more pronounced positive mood and stimulant-like effects, as well as stronger altered states of consciousness in individuals with depressive symptoms, compared to non-depressed individuals.

Acute Effects of Ad Libitum Use of Commercially Available Cannabis Products on the Subjective Experience of Aerobic Exercise: A Crossover Study

OBJECTIVE

The present study aimed to examine the acute effects of legal-market cannabis on regular cannabis users' subjective responses to exercise in a controlled laboratory environment.

BACKGROUND

Given the stereotype that cannabis is associated with extreme sedentary behavior, there are concerns that cannabis legalization may exacerbate the US physical inactivity epidemic. However, despite these concerns, recent years have seen considerable public interest in the use of cannabis concurrently with exercise (e.g., running).

METHODS

The present study compared participants' experiences of exercise without cannabis to their experiences of exercise after acute ad libitum use of one of two commercially available cannabis flower products: a Δ9-tetrahydrocannabinol-dominant or a cannabidiol-dominant product. Participants (N = 42) were regular cannabis users between the ages of 21 and 39 years (mean = 30.81 years, standard deviation = 4.72 years).

RESULTS

Although participants reported a more positive affect (p < 0.001), enjoyment (p < 0.001), and runner's high symptoms (p < 0.001) during their cannabis (vs non-cannabis) exercise appointment, they also reported more exertion (p = 0.04). Pain levels were very low and did not differ between appointments (p = 0.45). Effects appeared to depend, in part, on cannabinoid content; there was a larger difference in enjoyment (p = 0.02), and a smaller difference in exertion (p = 0.02), between the cannabis and non-cannabis exercise appointments among participants in the cannabidiol (vs Δ9-tetrahydrocannabinol) condition.

CONCLUSIONS

To our knowledge, this is the first study to investigate the acute effects of commercially available cannabis on subjective responses to exercise in a laboratory environment. Our findings suggest that, among regular cannabis users who use cannabis in combination with exercise, cannabis use prior to exercise may lead to increases in both positive and negative aspects of the subjective exercise experience. Research using diverse samples, exercise modalities, and methodologies (e.g., placebo-controlled trials) is needed to establish the generalizability of these findings.

A phase III multisite randomised controlled trial to compare the efficacy of cannabidiol to placebo in the treatment of cannabis use disorder: the CBD-CUD study protocol

BACKGROUND

Cannabis use disorder (CUD) is increasingly common and contributes to a range of health and social problems. Cannabidiol (CBD) is a non-intoxicating cannabinoid recognised for its anticonvulsant, anxiolytic and antipsychotic effects with no habit-forming qualities. Results from a Phase IIa randomised clinical trial suggest that treatment with CBD for four weeks reduced non-prescribed cannabis use in people with CUD. This study examines the efficacy, safety and quality of life of longer-term CBD treatment for patients with moderate-to-severe CUD.

METHODS/DESIGN

A phase III multi-site, randomised, double-blinded, placebo controlled parallel design of a 12-week course of CBD to placebo, with follow-up at 24 weeks after enrolment. Two hundred and fifty adults with moderate-to-severe CUD (target 20% Aboriginal), with no significant medical, psychiatric or other substance use disorders from seven drug and alcohol clinics across NSW and VIC, Australia will be enrolled. Participants will be administered a daily dose of either 4 mL (100 mg/mL) of CBD or a placebo dispensed every 3-weeks. All participants will receive four-sessions of Cognitive Behavioural Therapy (CBT) based counselling. Primary endpoints are self-reported cannabis use days and analysis of cannabis metabolites in urine. Secondary endpoints include severity of CUD, withdrawal severity, cravings, quantity of use, motivation to stop and abstinence, medication safety, quality of life, physical/mental health, cognitive functioning, and patient treatment satisfaction. Qualitative research interviews will be conducted with Aboriginal participants to explore their perspectives on treatment.

DISCUSSION

Current psychosocial and behavioural treatments for CUD indicate that over 80% of patients relapse within 1-6 months of treatment. Pharmacological treatments are highly effective with other substance use disorders but there are no approved pharmacological treatments for CUD. CBD is a promising candidate for CUD treatment due to its potential efficacy for this indication and excellent safety profile. The anxiolytic, antipsychotic and neuroprotective effects of CBD may have added benefits by reducing many of the mental health and cognitive impairments reported in people with regular cannabis use.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trial Registry: ACTRN12623000526673 (Registered 19 May 2023).

Cannabinoid Exposure and Subjective Effects of THC and CBD in Edible Cannabis Products

Background: The popularity of edible cannabis products continues to grow in states with legal cannabis access, but few studies have investigated the acute effects of these commercially available products. The present study sought to explore the effects of three commercially available edible products with different levels of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). Methods: A sample of regular cannabis users (N=99) were evaluated. Fifty participants completed the study procedures in-person, whereas 49 participants completed the study procedures remotely via Zoom. Subjective effects and plasma cannabinoid levels (in-person participants only) were assessed before and 2 h after participants self-administered one of three products ad libitum: a THC-dominant edible product, a CBD-dominant edible product, or a THC+CBD edible product. Results: At the 2-h post-use assessment, among in-person participants, plasma THC and CBD levels were robustly correlated with self-reported milligrams of THC and CBD consumed, respectively. Across all three conditions, in-person and remote participants experienced (1) an increase in subjective intoxication and elation, (2) a decrease in tension, and (3) no change in paranoia from pre-use to post-use. At post-use, participants who used a CBD product reported less intoxication relative to participants who used a THC+CBD or THC-only product. Participants who used a THC+CBD product reported consuming less THC-and displayed lower plasma THC levels (in-person participants)-relative to participants who used a THC-only product, despite reporting similar levels of positive (intoxication, elation, liking) and psychotomimetic (paranoia, tension) effects. Psychotomimetic effects were very low among both in-person and remote participants across all three conditions, and there were no post-use differences across conditions. Conclusions: Findings suggest that experienced users who consumed a THC+CBD product reported similar levels of positive and psychotomimetic effects relative to those who consumed a THC-only product, despite consuming less THC and displaying lower plasma THC concentrations. Given the potential harms associated with acute cannabis reward and long-term THC exposure, further research is needed to establish whether edible cannabis products with CBD pose less risk to users. Future studies should examine whether these effects generalize to samples of infrequent users, who may have less experience with edible cannabis use. ClinicalTrials.gov ID: NCT03522103.

Lack of effect of methamphetamine on reward-related brain activity in healthy adults

INTRODUCTION

Stimulant drugs are thought to alter processing of rewarding stimuli. However, the mechanisms by which they do this are not fully understood.

METHOD

In this study we used EEG to assess effects of single doses of methamphetamine (MA) on neural responses during anticipation and receipt of reward in healthy volunteers. Healthy young men and women (N = 28) completed three sessions in which they received placebo, a low MA dose (10 mg) or a higher MA dose (20 mg) under double blind conditions. Subjective and cardiovascular measures were obtained, and EEG was used to assess brain activity during an electrophysiological version of the Monetary Incentive Delay (eMID) task.

RESULTS

EEG measures showed expected patterns during anticipation and receipt of reward, and MA produced its expected effects on mood and cardiovascular function. However, MA did not affect EEG responses during either anticipation or receipt of rewards.

CONCLUSIONS

These findings suggest that the effects of MA on EEG signals of reward processing are subtle, and not related to the drug's effects on subjective feelings of well-being. The findings contribute to our understanding of the neural effects of MA during behaviors related to reward.

Assessment of the acute subjective psychedelic experience: A review of patient-reported outcome measures in clinical research on classical psychedelics

BACKGROUND

The classical psychedelics psilocybin, peyote, ayahuasca/ N, N-dimethyltryptamine, and lysergic acid diethylamide can temporarily produce altered states of consciousness, characterized by changes in sensory perception, thought, mood, and the sense of self-reality and meaning. It is important to have reliable instruments for quantifying these altered states in trials, due to a plausible link between the acute subjective experience and treatment outcome.

METHODS

We conducted a review of outcome measures applied in research on classical psychedelics to assess one or more dimensions of the acute subjective psychedelic experience. Three relevant databases were searched electronically. Two reviewers independently conducted article selection and data extraction regarding the instruments, dimensions, geography, population, and psychedelic substance investigated in the included studies. We identified the five most utilized instruments for the most recent 6 years, as well as the five most utilized instruments for each psychedelic.

RESULTS

We included 93 papers, which reported on 93 unique trials and utilized 17 different rating scales. Of these, the most utilized were the Five-Dimensional Altered States of Consciousness Questionnaire, visual analog or Likert scales specially developed for the trials, the Hallucinogen Rating Scale, the States of Consciousness Questionnaire, and the Abnormer Psychischer Zustand.

DISCUSSION

Considerable variability was found in the instruments utilized in clinical trials on classical psychedelics. We advise and encourage the development of a core outcome set for psychedelic research to enable altered state comparisons across compounds, participants, and settings. We further advise that instruments be designed to assess the "setting" of a psychedelic experience.

The effects of Lysergic Acid Diethylamide (LSD) on the Positive Valence Systems: A Research Domain Criteria (RDoC)-Informed Systematic Review

BACKGROUND AND OBJECTIVES

The renewed interest in psychedelic research provides growing evidence of potentially unique effects on various aspects of reward processing systems. Using the Research Domain Criteria (RDoC) framework, as proposed by the National Institute of Mental Health, we aim to synthesize the existing literature concerning the impact of lysergic acid diethylamide (LSD) on the RDoC's Positive Valence Systems (PVS) domain, and to identify potential avenues for further research.

METHODS

Two LSD-related terms (lysergic acid diethylamide and LSD) and 13 PVS-related terms (reward, happiness, bliss, motivation, reinforcement learning, operant, conditioning, satisfaction, decision making, habit, valence, affect, mood) were used to search electronic databases such as PubMed, Scopus, PsychINFO, and Web of Science for relevant articles. A manual search of the reference list resulted in nine additional articles. After screening, articles and data were evaluated and included based on their relevance to the objective of investigating the effects of LSD on the PVS. Articles and data were excluded if they did not provide information about the PVS, were observational in nature, lacked comparators or reference groups, or were duplicates. A risk of bias assessment was performed using the National Toxicology Program's Office of Health Assessment and Translation (NTP OHAT) risk of bias (RoB) tool. Data from the included articles were collected and structured based on the RDoC bio-behavioral matrix, specifically focusing on the PVS domain and its three constituent constructs: reward responsiveness, reward learning, and reward valuation.

RESULTS

We reviewed 28 clinical studies with 477 participants. Lysergic acid diethylamide, assessed at self-report (23 studies), molecular (5 studies), circuit (4 studies), and paradigm (3 studies) levels, exhibited dose-dependent mood improvement (20 short-term and 3 long-term studies). The subjective and neural effects of LSD were linked to the 5-HT2A receptor (molecular). Animal studies (14 studies) suggested LSD could mildly reinforce conditioned place preference without aversion and reduce responsiveness to other rewards. Findings on reward learning were inconsistent but hinted at potential associative learning enhancements. Reward valuation measures indicated potential reductions in effort expenditure for other reinforcers.

CONCLUSION

Our findings are consistent with our previous work, which indicated classical psychedelics, primarily serotonin 2A receptor agonists, enhanced reward responsiveness in healthy individuals and patient populations. Lysergic acid diethylamide exhibits a unique profile in the reward learning and valuation constructs. Using the RDoC-based framework, we identified areas for future research, enhancing our understanding of the impact of LSD on reward processing. However, applying RDoC to psychedelic research faces limitations due to diverse study designs that were not initially RDoC-oriented. Limitations include subjective outcome measure selection aligned with RDoC constructs and potential bias in synthesizing varied studies. Additionally, some human studies were open-label, introducing potential bias compared to randomized, blinded studies.

Effects of Oral Delta-9-Tetrahydrocannabinol in Women During the Follicular Phase of the Menstrual Cycle

Background: This study examined effects of oral delta-9-tetrahydrocannabinol (THC) in women at two phases of the menstrual cycle differing in circulating levels of estrogen (E). Pre-clinical findings indicate that E increases sensitivity to THC and other cannabinoids, raising the possibility that higher E may be a risk factor for adverse responses to THC in women. Methods: We examined subjective and behavioral responses to THC (7.5 and 15 mg oral) and placebo in women during the early follicular (EF) phase when E levels are low and the late follicular (LF) phase when E levels are higher. Outcome measures included self-report ratings of drug effects, cardiovascular measures, and biochemical verification of ovarian hormone levels. We hypothesized that women would exhibit greater responses to THC during the LF phase compared to the EF phase. Results: On most measures, responses to THC were similar during the two phases. However, on two self-report measures, "Wanting More" drug and anxiety, the effects occurred slightly earlier after drug administration in women who were tested during the EF phase. Conclusions: We conclude that the differences in levels of E occurring during the early and LF phase of the menstrual cycle do not strongly influence responses to THC. It remains to be determined whether responses are similarly stable across other cycle phases, or in women receiving exogenous hormone treatments.

Ventral prefrontal network response to alcohol in young adults with bipolar disorder: a within-subject randomized placebo-controlled alcohol administration study

Bipolar disorder co-occurs with alcohol use disorder at a rate 3-5 times higher than the general population. We recently reported that individuals with bipolar disorder differ in the positive stimulating and anxiolytic effects of alcohol compared with healthy peers. This study used a randomized, placebo-controlled, cross-over, within-subject alcohol administration design to investigate neurobiological mechanisms within ventral prefrontal cortical (vPFC) systems that may underlie altered sensitivity to alcohol in bipolar disorder (NCT04063384). Forty-seven young adults (n = 23 with bipolar disorder, 64% women) completed clinical assessment and two beverage administration sessions (alcohol and placebo, counter-balanced). Participants were dosed to 0.08 g% breath alcohol concentration during the alcohol condition and completed measures of subjective response to alcohol and an emotional processing fMRI task during the ascending limb. Timing during the placebo condition mirrored the alcohol session. Acute alcohol was associated with reduced functional connectivity between the insula - subcallosal cingulate cortex, and increased connectivity between the left nucleus accumbens - ventromedial PFC in bipolar disorder, but with no change in functional connectivity between these regions in healthy peers. Alcohol-related increases in nucleus accumbens - ventromedial PFC functional connectivity was associated with greater positive stimulating effects of alcohol in bipolar disorder and heavier recent alcohol use. Results suggest vPFC brain systems respond differently to acute alcohol during emotional processing in young adults with bipolar disorder compared with healthy peers, and that vPFC system responses relate to the subjective experience of intoxication and recent alcohol use.

The Study of Ketamine for Youth Depression (SKY-D): study protocol for a randomised controlled trial of low-dose ketamine for young people with major depressive disorder

BACKGROUND

Existing treatments for young people with severe depression have limited effectiveness. The aim of the Study of Ketamine for Youth Depression (SKY-D) trial is to determine whether a 4-week course of low-dose subcutaneous ketamine is an effective adjunct to treatment-as-usual in young people with major depressive disorder (MDD).

METHODS

SKY-D is a double-masked, randomised controlled trial funded by the Australian Government's National Health and Medical Research Council (NHMRC). Participants aged between 16 and 25 years (inclusive) with moderate-to-severe MDD will be randomised to receive either low-dose ketamine (intervention) or midazolam (active control) via subcutaneous injection once per week for 4 weeks. The primary outcome is change in depressive symptoms on the Montgomery-Åsberg Depression Rating Scale (MADRS) after 4 weeks of treatment. Further follow-up assessment will occur at 8 and 26 weeks from treatment commencement to determine whether treatment effects are sustained and to investigate safety outcomes.

DISCUSSION

Results from this trial will be important in determining whether low-dose subcutaneous ketamine is an effective treatment for young people with moderate-to-severe MDD. This will be the largest randomised trial to investigate the effects of ketamine to treat depression in young people.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry ID: ACTRN12619000683134. Registered on May 7, 2019. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=377513 .

Drug-induced social connection: both MDMA and methamphetamine increase feelings of connectedness during controlled dyadic conversations

MDMA is a stimulant-like drug with distinctive empathogenic effects. Its pro-social effects, such as feelings of connectedness, may contribute to both its popularity as a recreational drug and its apparent value as an adjunct to psychotherapy. However, little is known about the behavioral processes by which MDMA affects social interactions. This investigation examined the effects of MDMA (100 mg versus placebo; N = 18) on feelings of connectedness with an unfamiliar partner during a semi-structured casual conversation. A separate study examined the effects of a prototypic stimulant methamphetamine (MA; 20 mg versus placebo; N = 19) to determine the pharmacological specificity of effects. Oxytocin levels were obtained in both studies. Compared to placebo, both MDMA and MA increased feelings of connection with the conversation partners. Both MDMA and MA increased oxytocin levels, but oxytocin levels were correlated with feeling closer to the partner only after MDMA. These findings demonstrate an important new dimension of the pro-social effects of MDMA, its ability to increase feelings of connectedness during casual conversations between two individuals. Surprisingly, MA had a similar effect. The findings extend our knowledge of the social effects of these drugs, and illustrate a sensitive method for assessing pro-social effects during in-person dyadic encounters.

Nicotine flux as a powerful tool for regulating nicotine delivery from e-cigarettes: Protocol of two complimentary randomized crossover clinical trials

INTRODUCTION

Electronic cigarette (EC) use has increased rapidly in the last decade, especially among youth. Regulating nicotine delivery from ECs could help curb youth uptake and leverage EC use in harm reduction yet is complicated by varying device and liquid variables that affect nicotine delivery. Nicotine flux, the nicotine emission rate, is a parameter that incorporates these variables and focuses on the performance rather than the design of an EC. Nicotine flux therefore could be a powerful regulatory tool if it is shown empirically to predict nicotine delivery and subjective effects related to dependence.

METHODS AND ANALYSIS

This project consists of two complementary clinical trials. In Trial I, we will examine the relationship between nicotine flux and the rate and dose of nicotine delivery from ECs, hence, impacting abuse liability. It will also examine the extent to which this relationship is mediated by nicotine form (i.e., freebase versus protonated). At Yale School of Medicine (YSM), study participants will puff EC devices under conditions that differ by flux and form, while arterial blood is sampled in high time resolution. In Trial II, we will assess the relationship between nicotine flux, form, and subjective effects. At the American University of Beirut (AUB), participants will use EC devices with varying nicotine fluxes and forms, while dependency measures, such as the urge to use ECs, nicotine craving, and withdrawal symptoms, will be assessed. We will also monitor puffing intensity and real-time exposure to toxicants.

ETHICS AND DISSEMINATION

The protocol of Trial I and Trial II was approved by YSM and AUB IRBs, respectively. We will disseminate study results through peer-reviewed publications and conference presentations.

TRIAL REGISTRATION

NCT05706701 for Trial I and NCT05430334 for Trial II.

Opioid analgesic effects on subjective well-being in the operating theatre

Exposure to opioid analgesics due to surgery increases the risk of new persistent opioid use. A mechanistic hypothesis for opioids' abuse liability rests on the belief that, in addition to pain relief, acute opioid treatment improves well-being (e.g. via euphoria) and relieves anxiety. However, opioids do not consistently improve mood in laboratory studies of healthy non-opioid users. This observational study determined how two commonly used opioid analgesics affected patients' subjective well-being in standard clinical practice. Day surgery patients rated how good and how anxious they felt before and after an open-label infusion of remifentanil (n = 159) or oxycodone (n = 110) in the operating theatre before general anaesthesia. One minute after drug injection, patients reported feeling intoxicated (> 6/10 points). Anxiety was reduced after opioids, but this anxiolytic effect was modest (remifentanil Cohen's d = 0.21; oxycodone d = 0.31). There was moderate to strong evidence against a concurrent improvement in well-being (Bayes factors > 6). After remifentanil, ratings of 'feeling good' were significantly reduced from pre-drug ratings (d = 0.28). After oxycodone, one in three participants felt better than pre-drug. Exploratory ordered logistic regressions revealed a link between previous opioid exposure and opioid effects on well-being, as only 14 of the 80 opioid-naïve patients reported feeling better after opioid injection. The odds of improved well-being ratings after opioids were higher in patients with previous opioid exposure and highest in patients with > 2 weeks previous opioid use (adjusted OR = 4.4). These data suggest that opioid-induced improvement of well-being is infrequent in opioid-naïve patients. We speculate that peri-operative exposure could increase risk of persistent use by rendering subsequent positive opioid effects on well-being more likely.

Association Between Fatty Acid Amide Hydrolase and Alcohol Response Phenotypes: A Positron Emission Tomography Imaging Study With [11C]CURB in Heavy-Drinking Youth

BACKGROUND

Reductions in fatty acid amide hydrolase (FAAH), the catabolic enzyme for the endocannabinoid anandamide, may play a role in drinking behavior and risk for alcohol use disorder. We tested the hypotheses that lower brain FAAH levels in heavy-drinking youth are related to increased alcohol intake, hazardous drinking, and differential response to alcohol.

METHODS

FAAH levels in the striatum, prefrontal cortex, and whole brain were determined using positron emission tomography imaging of [11C]CURB in heavy-drinking youth (N = 31; 19-25 years of age). C385A FAAH genotype (rs324420) was determined. Behavioral (n = 29) and cardiovascular (n = 22) responses to alcohol were measured during a controlled intravenous alcohol infusion.

RESULTS

Lower [11C]CURB binding was not significantly related to frequency of use but was positively associated with hazardous drinking and reduced sensitivity to the negative effects of alcohol. During alcohol infusion, lower [11C]CURB binding related to greater self-reported stimulation and urges and lower sedation (p < .05). Lower heart rate variability was related to both greater alcohol-induced stimulation and lower [11C]CURB binding (p < .05). Family history of alcohol use disorder (n = 14) did not relate to [11C]CURB binding.

CONCLUSIONS

In line with preclinical studies, lower FAAH in the brain was related to a dampened response to the negative, impairing effects of alcohol, increased drinking urges, and alcohol-induced arousal. Lower FAAH might alter positive or negative effects of alcohol and increase urges to drink, thereby contributing to the addiction process. Determining whether FAAH influences motivation to drink through increased positive/arousing effects of alcohol or greater tolerance should be investigated.

Cannabinol (CBN; 30 and 300 mg) effects on sleep and next-day function in insomnia disorder ('CUPID' study): protocol for a randomised, double-blind, placebo-controlled, cross-over, three-arm, proof-of-concept trial

OBJECTIVE

Insomnia is the most prevalent sleep disorder, with few effective pharmacotherapies. Anecdotal reports and recent preclinical research suggest that cannabinol (CBN), a constituent of Cannabis sativa derived from delta-9-tetrahydrocannabinol, could be an effective treatment. Despite this, the isolated effects of CBN on sleep have yet to be systematically studied in humans.

METHODS

The present protocol paper describes a randomised, double-blind, placebo-controlled, single-dose, three-arm, cross-over, proof-of-concept study which investigates the effects of CBN on sleep and next-day function in 20 participants with clinician-diagnosed insomnia disorder and an Insomnia Severity Index Score ≥15. Participants receive a single fixed oral liquid dose of 30 mg CBN, 300 mg CBN and matched placebo, in random order on three treatment nights; each separated by a 2-week wash-out period. Participants undergo overnight sleep assessment using in-laboratory polysomnography and next-day neurobehavioural function tests. The primary outcome is wake after sleep onset minutes. Secondary outcomes include changes to traditional sleep staging, sleep-onset latency and absolute spectral power during non-rapid eye movement (NREM) sleep. Tertiary outcomes include changes to sleep spindles during NREM sleep, arousal indices, absolute spectral power during REM sleep and subjective sleep quality. Safety-related and exploratory outcomes include changes to next-day simulated driving performance, subjective mood and drug effects, postural sway, alertness and reaction time, overnight memory consolidation, pre and post-sleep subjective and objective sleepiness; and plasma, urinary, and salivary cannabinoid concentrations. The study will provide novel preliminary data on CBN efficacy and safety in insomnia disorder, which will inform larger clinical trials.

ETHICS AND DISSEMINATION

Human Research Ethics Committee approval has been granted by Bellberry (2021-08-907). Study findings will be disseminated in a peer-reviewed journal and at academic conferences.

TRIAL REGISTRATION NUMBER

NCT05344170.

Stimulant-like subjective effects of alcohol are not related to resting-state connectivity in healthy men

Individual differences in subjective, stimulant-like effects of alcohol are associated with the risk of developing alcohol use disorder. Specifically, individuals who experience more pronounced stimulant-like effects from alcohol are more likely to continue and escalate their usage. The neural basis for these individual differences in subjective response is not yet known. Using a within-subject design, 27 healthy male social drinkers completed three fMRI scans after ingesting a placebo, 0.4 and 0.8 g/kg alcohol, in a randomized order under double-blind conditions. Subjective stimulant effects of alcohol were assessed at regular intervals during each session. Seed-based and regional homogeneity analyses were conducted to evaluate changes in resting-state functional connectivity in relation to the stimulant effect of alcohol. Results indicated that 0.4 g/kg alcohol increased the connectivity to thalamus, and 0.8 g/kg alcohol decreased the connectivity to ventral anterior insula, primarily from the superior parietal lobule. Both doses reduced regional homogeneity in the superior parietal lobule but without an exact overlap with clusters showing connectivity changes in the seed-based analyses. The self-reported stimulant effect of alcohol was not significantly related to changes in seed-based connectivity or regional homogeneity. These findings suggest that alcohol-induced stimulation effects are not related to these indices of neural activity.

Imaging the brain's immune response to alcohol with [11C]PBR28 TSPO Positron Emission Tomography

In humans, the negative effects of alcohol are linked to immune dysfunction in both the periphery and the brain. Yet acute effects of alcohol on the neuroimmune system and its relationships with peripheral immune function are not fully understood. To address this gap, immune response to an alcohol challenge was measured with positron emission tomography (PET) using the radiotracer [11C]PBR28, which targets the 18-kDa translocator protein, a marker sensitive to immune challenges. Participants (n = 12; 5 F; 25-45 years) who reported consuming binge levels of alcohol (>3 drinks for females; >4 drinks for males) 1-3 months before scan day were enrolled. Imaging featured a baseline [11C]PBR28 scan followed by an oral laboratory alcohol challenge over 90 min. An hour later, a second [11C]PBR28 scan was acquired. Dynamic PET data were acquired for at least 90 min with arterial blood sampling to measure the metabolite-corrected input function. [11C]PBR28 volume of distributions (VT) was estimated in the brain using multilinear analysis 1. Subjective effects, blood alcohol levels (BAL), and plasma cytokines were measured during the paradigm. Full completion of the alcohol challenge and data acquisition occurred for n = 8 (2 F) participants. Mean peak BAL was 101 ± 15 mg/dL. Alcohol significantly increased brain [11C]PBR28 VT (n = 8; F(1,49) = 34.72, p > 0.0001; Cohen's d'=0.8-1.7) throughout brain by 9-16%. Alcohol significantly altered plasma cytokines TNF-α (F(2,22) = 17.49, p < 0.0001), IL-6 (F(2,22) = 18.00, p > 0.0001), and MCP-1 (F(2,22) = 7.02, p = 0.004). Exploratory analyses identified a negative association between the subjective degree of alcohol intoxication and changes in [11C]PBR28 VT. These findings provide, to our knowledge, the first in vivo human evidence for an acute brain immune response to alcohol.

IL-6, but not TNF-α, response to alcohol cues and acute consumption associated with neural cue reactivity, craving, and future drinking in binge drinkers

Objective and design

Preclinical studies suggest learned immune system responses to alcohol cues and consumption may contribute to alcohol's pharmacodynamic properties and/or Alcohol Use Disorder (AUD) pathogenesis. Mechanistically, these immune alterations may be associated with increased craving and alcohol consumption, both acutely and over time. We sought to characterize this relationship in a randomized, counter-balanced, crossover neuroimaging experiment which took place between June 2020-November 2021.

Methods

Thirty-three binge drinkers (BD) and 31 non-binge, social drinkers (SD), matched for demographic and psychological variables, were exposed to alcohol cues and water cues in two separate 7 T functional magnetic resonance imaging (fMRI) scans. Each scan was followed by the Alcohol Taste Test (ATT) of implicit motivation for acute alcohol. Craving measures and blood cytokine levels were collected repeatedly during and after scanning to examine the effects of alcohol cues and alcohol consumption on craving levels, Tumor necrosis factor alpha (TNF-α), and Interleukin 6 (IL-6) levels. A post-experiment one-month prospective measurement of participants' "real world" drinking behavior was performed to approximate chronic effects.

Results

BD demonstrated significantly higher peak craving and IL-6 levels than SD in response to alcohol cues and relative to water cues. Ventromedial Prefrontal Cortex (VmPFC) signal change in the alcohol-water contrast positively related to alcohol cue condition craving and IL-6 levels, relative to water cue condition craving and IL-6 levels, in BD only. Additionally, peak craving and IL-6 levels were each independently related to ATT alcohol consumption and the number of drinks consumed in the next month for BD, again after controlling for craving and IL-6 repones to water cues. However, TNF-α release in the alcohol cue condition was not related to craving, neural activation, IL-6 levels, immediate and future alcohol consumption in either group after controlling for water cue condition responses.

Conclusions

In sum, BD show greater craving and IL-6 release in the alcohol cue condition than SD, both of which were associated with prefrontal cue reactivity, immediate alcohol consumption, and future alcohol consumption over the subsequent 30 days. Alcohol associated immune changes and craving effects on drinking behavior may be independent of one another or may be indicative of a common pathway by which immune changes in BD could influence motivation to consume alcohol.

Trial registration

Clinical Trials NCT04412824.

Free-access intravenous alcohol self-administration in social drinkers and individuals with alcohol use disorder: Evaluation of relationships with phosphatidylethanol and self-reported alcohol consumption

BACKGROUND

The free-access (FA) intravenous alcohol self-administration (IV-ASA) paradigm is an experimental approach that can identify modulators of alcohol consumption in humans. Moreover, the outcome measures of IV-ASA paradigms are associated with self-reported alcohol intake using the timeline follow-back method (TLFB). To evaluate how FA IV-ASA reflects drinking in real life, we examined the relationship between an objective marker of recent alcohol intake, phosphatidylethanol in blood (B-PEth), and TLFB and measures obtained during IV-ASA in individuals with alcohol use disorder (AUD) and social drinkers (SD). We also explored the associations between these measures and gut-brain peptides involved in AUD pathophysiology.

METHODS

Thirty-eight participants completed a laboratory session in which they self-administered alcohol intravenously. The safety limit was 200 mg%, and main outcomes were mean and peak breath alcohol concentrations (BrAC). Blood samples were drawn prior to IV-ASA and subjective alcohol effects were rated during the experiment.

RESULTS

The study sample comprised 24 SD and 14 participants with DSM-5 mild AUD. Although BrACs were not associated with B-PEth or TLFB in the full sample or AUD subgroup, there was an association with TLFB in SD. In both subgroups, BrACs were associated with alcohol craving but with differential timing. Total ghrelin levels were higher in AUD participants than in SD.

CONCLUSIONS

No associations between B-PEth levels and achieved BrACs were observed in the mild AUD group, the SD group, or the full sample. The ability for FA IV-ASA to reflect recent drinking was confirmed only for TLFB in SD, whereas there were no associations within the smaller subsample of participants with mild AUD or in the full sample. Further studies that include a larger AUD sample are warranted. The association of BrACs with craving for alcohol suggests that the IV-ASA method may be useful for assessing interventions that target craving. This could be explored by using the FA IV-ASA model to evaluate the effects on craving of approved pharmacotherapies for AUD.

Preliminary assessment of the subjective effects of electronic-cigarettes in young-adult low-dose electronic-cigarette users: Effects of nicotine dose and e-liquid flavor

OBJECTIVE

The present study evaluated the effects of nicotine concentration (0-10 mg/ml) and flavor (gummy bear vs unflavored) on the subjective experiences of vaporized nicotine in young adult low-dose nicotine (3 mg/ml) ECIG users.

PARTICIPANTS

Eight young adult ECIG users were recruited.

METHODS

A single blinded crossover study was used. Participants were instructed to take ten 1.5 second puffs, each separated by 20 seconds. After self-administration, heart rate was recorded, and participants completed the Drug Effects, Direct Effects of Nicotine, and Direct Effects of ECIG questionnaires.

RESULTS

ECIG user's standard daily nicotine dose influenced the rewarding and aversive effects of nicotine as the 10 mg/ml dose was found to be aversive in this user group. The combination of flavor and nicotine increased the subjective effects of ECIGs.

CONCLUSIONS

Flavored e-liquids contribute to the reinforcing properties of nicotine by enhancing the subjective effects, which may lead to continued ECIG use.

Assessing real-time positive subjective effects of alcohol using high-resolution ecological momentary assessment in risky versus light drinkers

BACKGROUND

High-resolution ecological momentary assessment (HR-EMA) can assess acute alcohol responses during naturalistic heavy drinking episodes. The goal of this study was to use HR-EMA to examine drinking behavior and subjective responses to alcohol in risky drinkers (moderate-severe alcohol use disorder [MS-AUD], heavy social drinkers [HD]) and light drinkers (LD). We expected that risky drinkers would endorse greater alcohol stimulation and reward, with lower sedation, than LD, even when controlling for amount of alcohol consumed.

METHODS

Participants (N = 112; 54% male, M ± SD age = 27.2 ± 4.2 years) completed smartphone-based HR-EMA during one typical alcohol drinking occasion and one non-alcohol-drinking occasion in their natural environment. Participants were prompted to complete next-day surveys that assessed drinking-related outcomes, study acceptability, and safety.

RESULTS

HR-EMA prompt completion rates were excellent (92% and 89% for the alcohol and nonalcohol episodes, respectively). The MS-AUD group consumed the most alcohol with the highest estimated blood alcohol concentration (eBAC) by the end of the alcohol drinking episode (0.14 g/dL) versus LD (0.02 g/dL), with HD intermediate (0.10 g/dL). Relative to LD, MS-AUD and HD endorsed greater positive effects of alcohol (stimulation, liking, and wanting).

CONCLUSIONS

This study is the first to use HR-EMA to measure and compare real-world acute alcohol responses across diverse drinker subgroups, including persons with MS-AUD. Results demonstrate that risky drinkers experience heightened pleasurable effects measured in real-time during natural-environment alcohol responses. Rather than drinking excessively to eventually achieve desirable subjective effects, risky drinkers show sensitivity to positive alcohol effects throughout a heavy drinking episode.

Methamphetamine enhances neural activation during anticipation of loss in the monetary incentive delay task

Stimulants like methamphetamine (MA) affect motivated behaviors via actions on circuits mediating mood, attention, and reward. Few studies examined the effects of single doses of stimulants on reward circuits during anticipation and receipt of rewards and losses. Here, we examined the effects of MA (20 mg) or placebo in a within-subject, double-blind study with healthy adults (n = 43). During 2 fMRI sessions, participants completed the monetary incentive delay task. Primary outcome measures were BOLD activation in selected regions of interest during anticipation and receipt of monetary rewards and losses. Secondary analyses included behavioral measures, whole brain analysis, and arterial spin labeling. MA produced its expected behavioral effects and increased neural activation in the ventral striatum and anterior insula during anticipation of monetary loss versus non-loss. MA did not affect activation during anticipation of gains, or during receipt of wins or losses. MA significantly reduced cerebral blood flow in the striatum and insula. The present finding that a stimulant enhances the responses of striatal and insular regions to upcoming loss suggests that this system may be sensitive to the salience of upcoming events. The finding adds to a complex body of evidence regarding the effects of stimulant drugs on neural processes during motivated behaviors.