Comparison of the subjective effects of Delta(9)-tetrahydrocannabinol and marijuana in humans

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.

Vaporized D-limonene selectively mitigates the acute anxiogenic effects of Δ9-tetrahydrocannabinol in healthy adults who intermittently use cannabis

BACKGROUND

Cannabis contains hundreds of chemical constituents beyond delta-9-tetrahydrocannabinol (THC), which is believed to drive most of its acute pharmacodynamic effects. The entourage effect theory asserts that non-THC constituents can impact acute cannabis effects, but few empirical studies have systematically evaluated this theory in humans. This study assessed whether the cannabis terpenoid d-limonene mitigates the acute anxiogenic effects of THC.

METHODS

Twenty healthy adults completed nine, double-blind outpatient sessions in which they inhaled vaporized THC alone (15mg or 30mg), d-limonene alone (1mg or 5mg), the same doses of THC and d-limonene together, or placebo; a subset of participants (n=12) completed a tenth session in which 30mg THC+15mg d-limonene was administered. Outcomes included subjective drug effects, cognitive/psychomotor performance, vital signs, and plasma THC and d-limonene concentrations.

RESULTS

When d-limonene was administered alone, pharmacodynamic outcomes did not differ from placebo. Administration of 15mg and 30mg THC alone produced subjective, cognitive, and physiological effects typical of acute cannabis exposure. Ratings of anxiety-like subjective effects qualitatively decreased as d-limonene dose increased and concurrent administration of 30mg THC+15mg d-limonene significantly reduced ratings of "anxious/nervous" and "paranoid" compared with 30mg THC alone. Other pharmacodynamic effects were unchanged by d-limonene. D-limonene plasma concentrations were dose orderly, and concurrent administration of d-limonene did not alter THC pharmacokinetics.

CONCLUSIONS

D-limonene selectively attenuated THC-induced anxiogenic effects, suggesting this terpenoid could increase the therapeutic index of THC. Future research should determine whether this effect extends to oral dose formulations and evaluate the interactions between other cannabis terpenoids or cannabinoids and THC.

Distinct antinociceptive and conditioned behavioral effects are produced by individual cannabinoids and a cannabis-derived mixture

Cannabinoids have been proposed as therapeutics for pain mitigation. Therefore, the antihyperalgesic effects of a proprietary cannabis-derived mixture, Non-Euphoric Phytocannabinoid Elixir #14 (NEPE14), were examined in a persistent Complete Freund's Adjuvant (CFA)-induced model of inflammatory pain. The acute antinociceptive and operant behavioral effects of NEPE14 were then compared with single cannabinoid preparations of Δ9-tetrahydrocannabinol (Δ9-THC), Δ8-THC, the synthetic cannabinoid (-)-CP 55,940 (CP), and cannabidiol (CBD). The THC isomers and CP were also administered with cannabinoid-type-1 receptor (CB1R) antagonist, AM251, and NEPE14 was administered in combination with THC or CP. To induce inflammation, CFA or saline was administered into the paw of male and female Wistar rats. After injections, mechanical hypersensitivity was assessed with Von Frey filaments, and thermal hyperalgesia with a thermal probe. Nine Sprague Dawley rats were also trained to respond under a fixed-ratio 30 schedule for food reinforcers during a 60-min session. Response rates were recorded during the session and warm-water tail-withdrawal latency post session. In CFA-administered rats, mechanical and thermal paw-withdrawal thresholds significantly decreased compared to vehicle, indicating hyperalgesia. Both i.p. (6.6-20.7 ml/kg) and o.m. (30-300 μL) NEPE14 significantly reduced the mechanical and thermal hyperalgesia. In contrast, neither NEPE14 (3.7-20.7 mL/kg i.p., 100-1000 μL o.m.) nor CBD (10-100 mg/kg) significantly decreased response rates or increased tail-withdrawal latency. Acute Δ9-THC, Δ8-THC (1-5.6 mg/kg), and CP (0.032-0.18 mg/kg) significantly and dose-dependently decreased overall response rate and increased tail-withdrawal latency compared to vehicle. AM251 significantly antagonized the rate-decreasing effects of THC, and CP, as well as the antinociceptive effects of CP. Combinations of NEPE14 with Δ9-THC or CP were not significantly different from these cannabinoids alone. In summary, while NEPE14 significantly reduced CFA-induced hyperalgesia, it was more similar to CBD than Δ9-THC, Δ8-THC, and CP for significantly reducing thermal nociception and disrupting conditioned behavior.

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.

Does the "Entourage Effect" in Cannabinoids Exist? A Narrative Scoping Review

Background: The concept of an "entourage" effect in the cannabis and cannabinoids' field was first introduced in the late 1990s, during a period when most research on medical cannabinoids focused on the effects of isolated cannabinoids, such as cannabidiol and Δ9-tetrahydrocannabinol. Over the past decade, however, with the increased understanding of the endocannabinoid system, the discovery of other phytocannabinoids and their potential therapeutic uses, the term has gained widespread use in scientific reviews and marketing campaigns. Objective: Critically review the application of the term "entourage effect (EE)" in the literature and its endorsement by certain sectors of the cannabis market. Also, explore the perspectives for further interpretation and elaboration of the term based on current evidence, aiming to contribute to a more nuanced understanding of the concept and its implications for cannabinoid-based medicine. Methods: A comprehensive review of the literature was conducted to evaluate the current state of knowledge regarding the entourage effect. Relevant studies and scientific reviews were analyzed to assess the evidence of clinical efficacy and safety, as well as the regulation of cannabinoid-containing product production. Results: The EE is now recognized as a synergistic phenomenon in which multiple components of cannabis interact to modulate the therapeutic actions of the plant. However, the literature provides limited evidence to support it as a stable and predictable phenomenon. Hence, there is also limited evidence to support clinical efficacy, safety, and appropriate regulation for cannabinoid-containing products based on a "entourage" hypothesis. Conclusion: The EE has significant implications for the medical use of cannabinoid-containing products and their prescription. Nevertheless, a critical evaluation of the term's application is necessary. Further research and evidence are needed to establish the clinical efficacy, safety, and regulatory framework for these products. It's crucial that regulators, the pharmaceutical industry, the media, and health care providers exercise caution and avoid prematurely promoting the entourage effect hypothesis as a scientific proven phenomenon for cannabinoids and other cannabis-derived compound combinations.

E-cigarettes may serve as a gateway to conventional cigarettes and other addictive drugs

Electronic cigarettes (e-cigarettes) are devices that allow the user to inhale nicotine in a vapor, and are primarily marketed as a means of quitting smoking and a less harmful replacement for traditional cigarette smoking. However, further research is needed to determine if vaping nicotine via e-cigarettes can be effective. Conversely, nicotine has been considered a gateway drug to alcohol and other addictive drugs and e-cigarettes containing nicotine may have the same effects. Previous reports have shown that e-cigarette use may open the gate for the use of other drugs including conventional cigarettes, cannabis, opioids, etc. The increasing prevalence of e-cigarettes, particularly among youth and adolescents in the last decade have led to an increase in the dual use of e-cigarettes with alcohol, cannabis, and other illicit drug use like heroin and 3-4-methylenedioxymethamphetamine (MDMA). The advent of e-cigarettes as a device to self-administer addictive agents such as cocaine and synthetic cathinones may bring about additional adverse health effects associated with their concurrent use. This review aims to briefly describe e-cigarettes and their different generations, and their co-use with other addictive drugs as well as the use of the device as a tool to self-administer addictive drugs, such as cocaine, etc.

Cannabinoid modulation of corticolimbic activation during extinction learning and fear renewal in adults with posttraumatic stress disorder

Failure to successfully extinguish fear is a hallmark of trauma-related disorders, like posttraumatic stress disorder (PTSD). PTSD is also characterized by dysfunctional corticolimbic activation and connectivity. The endocannabinoid system is a putative system to target for rescuing these behavioral and neural deficits. In healthy adults, acute, low-dose delta-9-tetrahydrocannabinol (THC) facilitates fear extinction and increases cortico-limbic activation and connectivity in response to threat. The present study determines the effect of acute, low-dose THC on fear-related brain activation and connectivity during fear extinction in trauma-exposed adults with (PTSD = 19) and without PTSD [trauma-exposed controls (TEC) = 26] and non-trauma-exposed [healthy controls (HC) = 26]. We used a Pavlovian fear conditioning and extinction paradigm, where we measured concurrent functional magnetic resonance imaging (fMRI) and behavioral responses (i.e., skin conductance responding and expectancy ratings). Using a randomized, double-blind, placebo-controlled design, N = 71 subjects were randomized to receive placebo (PBO, n = 37) or THC (n = 34) prior to fear extinction learning. During early extinction learning, individuals with PTSD given THC had greater vmPFC activation than their TEC counterparts. During a test of the return of fear (i.e., renewal), HC and individuals with PTSD given THC had greater vmPFC activation compared to TEC. Individuals with PTSD given THC also had greater amygdala activation compared to those given PBO. We found no effects of trauma group or THC on behavioral fear indices during extinction learning, recall, and fear renewal. These data suggest that low dose, oral THC can affect neural indices of fear learning and memory in adults with trauma-exposure; this may be beneficial for future therapeutic interventions seeking to improve fear extinction learning and memory.

Increased White Matter Coherence Following Three and Six Months of Medical Cannabis Treatment

Background: Previous studies have demonstrated abnormal white matter (WM) microstructure in recreational cannabis consumers; however, the long-term impact of medical cannabis (MC) use on WM coherence is unknown. Accordingly, this study assessed the longitudinal impact of MC treatment on WM coherence. Given results from preclinical studies, we hypothesized that MC treatment would be associated with increased fractional anisotropy (FA) and reduced mean diffusivity (MD). Methods: As part of a larger, longitudinal investigation, patients interested in treating at least one medical condition with commercially available MC products of their choosing were assessed before initiating MC use (baseline n=37; female=25, male=12) and following three (n=31) and six (n=22) months of treatment. WM coherence was assessed via diffusion tensor imaging for bilateral regions of interest including the genu of the corpus callosum, anterior limb of the internal capsule, external capsule, and anterior corona radiata, as well as an occipital control region not expected to change over time. Results: In MC patients, FA values significantly increased bilaterally in several callosal regions relative to baseline following both 3 and 6 months of treatment; MD values significantly decreased in all callosal regions but only following 6 months of treatment. No significant changes in WM coherence were observed in the control region or in a pilot sample of treatment-as-usual patients (baseline n=14), suggesting that increased WM coherence observed in MC patients may be attributed to MC treatment as opposed to confounding factors. Interestingly, significant reductions in MD values correlated with higher cannabidiol (CBD) exposure but not Δ-9-tetrahydrocannabinol exposure. Conclusions: Overall, MC treatment was associated with increased WM coherence, which contrasts with prior research examining recreational cannabis consumers, likely related to inherent differences between recreational consumers and MC patients (e.g., product choice, age of onset). In addition, increased CBD exposure was associated with reduced MD following 6 months of treatment, extending evidence from preclinical research indicating that CBD may be neuroprotective against demyelination. However, additional research is needed to elucidate the clinical efficacy of MC treatment and the risks and benefits of long-term MC use.

Cannabinoid modulation of brain activation during volitional regulation of negative affect in trauma-exposed adults

Emotion dysregulation is considered a core component of posttraumatic stress disorder (PTSD). Cognitive reappraisal is one therapeutic emotion regulation strategy that has been widely studied among individuals with mood and anxiety disorders, and numerous differences in brain activation patterns have been shown between individuals with and without PTSD during tasks of cognitive reappraisal. Prior research among healthy subjects suggests that an acute, low dose of Δ9-tetrahydrocannabinol (THC) could attenuate the neurophysiological discrepancies that exist between individuals with and without PTSD during tasks of emotional processing; however, the effect of an acute, low dose of THC on corticolimbic activity during emotion regulation among individuals with PTSD has not yet been studied. The present study aimed to investigate the effect of THC on negative affect and brain activation in a priori regions of interest during cognitive reappraisal among trauma-exposed individuals with and without PTSD. Using a double-blind design, 51 individuals were randomized to receive THC or placebo (PBO) before participating in a well-established emotion regulation task during functional magnetic resonance imaging (fMRI). THC but not PBO reduced negative affect during reappraisal, and THC increased dorsomedial prefrontal cortex (dmPFC) activation in response to neutral images. Individuals with PTSD displayed less activation in the angular gyrus, overall, compared to the trauma-exposed control (TEC) group, however THC increased angular gyrus activation in the PTSD group so that there was no significant difference in angular gyrus activation between the TEC and PTSD groups that received THC. Compared to PBO, THC also increased cerebellar activation during exposure to neutral images in individuals with PTSD. Lastly, in participants that received THC, greater posterior cingulate cortex (PCC)/precuneus activation during reappraisal was associated with less self-reported negative affect following reappraisal blocks. Together these findings suggest that THC may prove to be a beneficial pharmacological adjunct to cognitive reappraisal therapy in the treatment of PTSD.

The effects of oral and vaporized cannabis alone, and in combination with alcohol, on driving performance using the STISIM driving simulator: A two-part, double-blind, double-dummy, placebo-controlled, randomized crossover clinical laboratory protocol

The legalization of cannabis for medicinal and non-medicinal purposes, and the corresponding increase in diversity of cannabis products, has resulted an urgent need for cannabis regulatory science. Among the most pressing needs is research related to impairment due to cannabis exposure, especially on driving performance. The present project was designed to evaluate the impact of oral and vaporized cannabis, when administered alone or in combination with alcohol, on simulated driving performance (STISIM driving simulator), cognitive/psychomotor ability, and field sobriety performance. Healthy adults will complete two, double-blind, double-dummy, placebo-controlled, randomized crossover clinical laboratory studies, one with oral cannabis (16 men/16 women) and the second with vaporized cannabis (16 men/16 women). In each study, participants will complete seven experimental sessions during which acute doses of placebo or high Δ9-THC cannabis containing 0, 10, or 25 mg Δ9-THC will be administered both alone and in combination with placebo or alcohol-containing beverages (target breath alcohol concentrations, BAC, of 0.0% or 0.05%). A positive control session (i.e., alcohol at target BAC of 0.08% with placebo cannabis) will also be completed. Simulated driving performance tests (available for download; see Methods), field sobriety assessments, subjective drug effect questionnaires, a mobile device impairment test (DRUID app), and collection of whole blood specimens will be completed repeatedly during each session. Linear mixed models will be used to test for differences across experimental conditions and a priori planned comparisons will be used to determine differences between conditions of interest (e.g., cannabis alone vs cannabis with alcohol). This research is designed to extend prior studies of cannabis and alcohol on driving performance by using oral and vaporized routes of cannabis administration. By increasing understanding of impairment associated with co-use of alcohol and these novel forms of cannabis, this research could inform impairment detection standards for cannabis and alcohol and have important implications for law enforcement, public policy decisions regarding accessibility of these substances, and education of the general population who may use cannabis and/or alcohol. Lastly, this manuscript provides interested researchers with access to the simulated driving scenarios and data extraction tools developed for this study as a means of facilitating future cross-study comparisons, which is important given the heterogeneity in methods used across laboratories in prior research.

Δ9-THC reduces reward-related brain activity in healthy adults

RATIONALE

Greater availability of cannabis in the USA has raised concerns about adverse effects of the drug, including possible amotivational states. Lack of motivation may be assessed by examining acute effects of cannabinoids on reward processing.

OBJECTIVES

This study examined single doses of delta-9-tetrahydrocannabinol (∆9-THC; 7.5, 15 mg oral) in healthy adults using a version of the monetary incentive delay (MID) task adapted for electroencephalography (EEG; e-MID) in a within-subjects, double blind design.

METHODS

Two phases of reward processing were examined: anticipation, which occurs with presentation of cues that indicate upcoming reward, punishment, or neutral conditions, and outcome, which occurs with feedback indicating hits or misses. During anticipation, we measured two event-related potential (ERP) components: the P300, which measures attention and motivation, and the LPP, which measures affective processing. During outcome processing, we measured P300 and LPP, as well as the RewP, which measures outcome evaluation.

RESULTS

We found that ∆9-THC modulated outcome processing, but not reward anticipation. Specifically, both doses of ∆9-THC (7.5 and 15 mg) reduced RewP amplitudes after outcome feedback (hits and misses) relative to placebo. ∆9-THC (15 mg) also reduced P300 and LPP amplitudes following hits compared to misses, relative to both placebo and 7.5 mg ∆9-THC.

CONCLUSIONS

These findings suggest that ∆9-THC dampens responses to both reward and loss feedback, which may reflect an "amotivational" state. Future studies are needed to determine generalizability of this effect, such as its pharmacological specificity and its specificity to monetary vs other types of reward.

Effects of Cannabis-Delivered THC on mood and negative attentional bias in the context of positive vs. neutral Alternatives-a pilot study

OBJECTIVE

To assess: (1) the acute effects of smoked marijuana (MJ) on negative attentional bias (NAB), (2) moderation of these effects by positive versus neutral alternatives, and (3) the associations of tetrahydrocannabinol (THC)-induced changes in NAB with changes in affect.

METHODS

Fourteen MJ users (1-4 uses/wk) smoked a THC cigarette on 1 day and a placebo cigarette on the other counterbalanced day. After smoking, participants freely gazed back and forth at a series of two side-by-side pictures pairs presented for 3000 ms (one negative, while the other was either positive or neutral) while eye gaze was tracked.

RESULTS

The effects of THC relative to placebo varied across time such that THC increased NAB during the early temporal component of threatening picture viewing, 333-858 ms after dual-picture onset, regardless of alternative picture valance. However, contrary to the attentional bias-causes affect hypothesis, during the early viewing phase THC-enhanced positive affect (PA) correlated positively with THC-induced NAB. In contrast, during the late phase (891-3000 ms) THC-enhanced PA did not correlate significantly with NAB, though THC-induced negative affect (NA) change did correlate positively with THC-induced change in NAB in the positive alternative condition.

CONCLUSIONS

We replicated findings of others showing that THC can enhance NAB during the early stages of threatening picture viewing. We extended previous results by demonstrating the THC-induced NAB is associated with increased PA during initial threat viewing, but with increased NA during later processing if positive alternatives are present.

Adolescents are more sensitive than adults to acute behavioral and cognitive effects of THC

Increased cannabis availability has contributed to increased use with concomitant incidence of adverse effects. One risk factor for adverse drug reactions may be age. There is preclinical evidence that acute effects of delta-9-tetrahydrocannabinol (THC), the primary active constituent of cannabis, are greater during adolescence, but this has not been fully studied in humans. The present study sought to determine whether adolescent men and women are more sensitive than adults to acute THC. Adolescents aged 18-20 (N = 12) and adults aged 30-40 (N = 12), with less than 20 total lifetime uses of THC-containing products, received capsules of THC (7.5, 15 mg) and placebo across three study sessions in randomized order under double blind conditions. During each session, subjective, cardiovascular, behavioral, and EEG measures were obtained. Behavioral measures included Simple Reaction Time, Stop Task, Time Production and N-back and EEG measures included P300 amplitudes during an auditory oddball task and eyes-closed resting state. THC affected subjective state and heart rate similarly in both age groups. However, adolescents were more sensitive to performance impairing effects, exhibiting dose-dependent impairments on reaction time, response accuracy, and time perception. On EEG measures, THC dose-dependently decreased P300 amplitude in adolescents but not adults. Adolescents were more sensitive to behavioral and cognitive effects of THC, but not to cardiovascular effects or subjective measures. Thus, at doses that produce comparable ratings of intoxication, adolescents may exhibit greater cognitive impairment and alterations in brain function.

Acute effects of oral delta-9-tetrahydrocannabinol (THC) on autonomic cardiac activity and their relation to subjective and anxiogenic effects

Cannabis is the most commonly used psychotropic drug in the United States, after alcohol. Despite its apparent sedative and calming effects, cannabis and its main psychoactive constituent, ∆⁹ -tetrahydrocannabinol (THC) can produce serious adverse effects including tachycardia and anxiety. These effects can be especially pronounced in women, who remain underrepresented in clinical cannabinoid research. The present study is one of the first to characterize the effects of single doses of oral THC on autonomic nervous system function in healthy adult women. Occasional female cannabis users participated in three laboratory sessions in which they received oral THC (7.5 and 15 mg) and placebo. Autonomic measures included heart rate (HR), blood pressure (BP), pre-ejection period (PEP) a measure of cardiac sympathetic functioning, and high frequency heart rate variability (HF-HRV) a measure of parasympathetic cardiac control. Autonomic responses were examined in relation to subjective drug effects. THC dose-dependently increased HR, decreased HF-HRV, and increased ratings of feeling a drug effect, cannabis-like intoxication, and anxiety. Although the drug did not significantly affect BP or PEP, HR was negatively related to both PEP and HF-HRV. HF-HRV, the measure of parasympathetic activity, was significantly negatively related to subjective measures of cannabis intoxication (but not anxiety) at the 15 mg dose only. PEP was not significantly related to any subjective measure. These results extend our knowledge of the autonomic effects of THC in relation to subjective drug experience. This and future studies will help us to understand risk factors related to cannabis use.

A naturalistic study of orally administered vs. inhaled legal market cannabis: cannabinoids exposure, intoxication, and impairment

RATIONALE

Published studies examining the effects of cannabis have largely utilized forms of cannabis that are not representative of the legal market products currently available.

OBJECTIVES

The present study aimed to characterize naturalistic use of legal market flower and edible products by examining associations among blood cannabinoids and amount of THC consumed as well as physiological, cognitive, and subjective effects in users of edible and flower forms.

METHOD

Eighty-four participants who used cannabis at least 1 × /week (55 flower cannabis using participants; 29 edible cannabis using participants mean age = 31.95 years, 44% female) participated. At the experimental appointment in our mobile laboratory, participants completed a blood draw to assess plasma cannabinoids, measures of heart rate, subjective drug effects, and cognition both before and after ad libitum use of legal market flower or edible cannabis.

RESULTS

Average self-reported THC consumed was 15.97 mg (SD = 22.40) in edible users and 51.25 mg (SD = 45.23) in flower users. In the edible group, but not the flower group, strong correlations emerged between self-reported ad libitum THC consumed and plasma THC. Plasma THC was significantly higher after use of inhaled cannabis, but similar levels of plasma THC metabolites and similar levels of subjective intoxication and verbal memory impairment were observed in both flower and edible users.

CONCLUSIONS

Findings support strong correlations among ad libitum THC consumed and THC plasma levels after edible cannabis use and suggest few differences in intoxication and impairment between edible and flower cannabis users after ad libitum use. This novel study provides important preliminary data on the pharmacology and effects of legal market edible cannabis.

Delta-9-tetrahydrocannabinol reduces willingness to exert effort in women

BACKGROUND

The use of cannabis has been clinically associated with decreased motivation to engage in normally rewarding activities. However, evidence from previous controlled studies is mixed.

METHOD

In this study, we examined the effects of acute delta-9-tetrahydrocannabinol (THC) versus placebo on a task measuring willingness to exert effort for rewards. This is a secondary analysis of a larger study examining interactions between ovarian hormones and THC. In this within-subjects study, oral THC and placebo were administered under double-blind conditions in counterbalanced order to healthy young adult (M age = 24 years) women with previous cannabis experience who were not regular users. Forty subjects completed three 4-h sessions with PL, 7.5 and 15 mg THC, while an additional 18 completed only PL and 15 mg THC sessions (design abridged due to pandemic). At each session, they completed a task consisting of making repeated choices between a hard and an easy task, which were worth varying amounts of money at varying probabilities.

RESULTS

THC dose-dependently decreased hard task choices (drug effect, b =  - 0.79, SE = 0.29, z =  - 2.67, p < 0.01), especially at moderate to high expected values of reward (drug × probability × amount interaction, b = 0.77, SE = 0.38, z = 1.99, p = 0.04). THC also slowed task performance (drug effect, b = 0.01, SE = 0.005, t(5.24) = 2.11, p = 0.04), but the effect of THC on choice was still significant after controlling for this psychomotor slowing.

CONCLUSIONS

These findings support the idea that cannabis acutely reduces motivation to earn non-drug rewards. Still to be determined are the neurochemical mechanisms underlying this effect.

Acute objective and subjective intoxication effects of legal-market high potency THC-dominant versus CBD-dominant cannabis concentrates

As the market for cannabis concentrate products grows, the lack of research regarding the effects of concentrated THC and CBD becomes more glaring. The present study analyzes cannabinoid blood levels and subjective outcomes of physical sensation and affective state after ad libitum use of legal-market concentrate products. Recreational cannabis users were randomly assigned to THC- or CBD-dominant concentrate products, completing a baseline session, and an experimental mobile laboratory session consisting of timepoints before, immediately after, and one-hour after concentrate use. THC-dominant concentrates induced higher intoxication, and higher ratings of drug effect and drug liking than the CBD-dominant concentrate. Both products induced immediate feelings of elation, diminishing over the subsequent hour. Subjective outcomes in the CBD-dominant group revealed immediate decreases in tension and anxiety relative to pre-use, while the THC-dominant group only saw significant decreases in anxiety after one hour. Paranoia spiked immediately post-use in THC-dominant concentrate users, returning to baseline within an hour. Overall, the CBD-dominant concentrate invoked positive mood effects, lower intoxication and an absence of undesirable effects experienced with the THC-dominant concentrate, potentially mitigating negative effects when combined. Results support the need for further investigation into harm-reduction potential of concentrated CBD when used alone and with THC.

Advancing the science on cannabis concentrates and behavioural health

ISSUES

The Cannabis sativa L. plant contains hundreds of phytocannabinoids, but putatively of highest importance to public health risk is the psychoactive cannabinoid delta-9-tetrahydrocannabinol (THC), which is associated with risk for cannabis use disorder, affective disturbance, cognitive harm and psychomotor impairment. Recently, there has been an increase in the use and availability of concentrated cannabis products (or 'concentrates') that are made by extracting cannabinoids from the plant to form a product with THC concentrations as high as 90-95%. These products are increasingly popular nationwide. The literature on these widely available high potency concentrates is limited and there are many unknowns about their potential harms.

APPROACH

This review covers the state of the research on cannabis concentrates and behavioural health-related outcomes and makes recommendations for advancing the science with studies focused on accurately testing the risks in relation to critical public and behavioural health questions.

KEY FINDINGS

Data point to unique behavioural health implications of concentrate use. However, causal, controlled and representative research on the effects of cannabis concentrates is currently limited.

IMPLICATIONS

Future research is needed to explore chronic, acute and developmental effects of concentrates, as well as effects on pulmonary function. We also highlight the need to explore these relationships in diverse populations.

CONCLUSION

While the literature hints at the potential for these highly potent products to increase cannabis-related behavioural health harms, it is important to carefully design studies that more comprehensively evaluate the impact of concentrates on THC exposure and short- and long-term effects across user groups.

An Observational, Longitudinal Study of Cognition in Medical Cannabis Patients over the Course of 12 Months of Treatment: Preliminary Results

OBJECTIVE

Cannabis use has increased dramatically across the country; however, few studies have assessed the long-term impact of medical cannabis (MC) use on cognition. Studies examining recreational cannabis users generally report cognitive decrements, particularly in those with adolescent onset. As MC patients differ from recreational consumers in motives for use, product selection, and age of onset, we assessed cognitive and clinical measures in well-characterized MC patients over 1 year. Based on previous findings, we hypothesized MC patients would not show decrements and might instead demonstrate improvements in executive function over time.

METHOD

As part of an ongoing study, MC patients completed a baseline visit prior to initiating MC and evaluations following 3, 6, and 12 months of treatment. At each visit, patients completed a neurocognitive battery assessing executive function, verbal learning/memory, and clinical scales assessing mood, anxiety, and sleep. Exposure to delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) was also quantified.

RESULTS

Relative to baseline, MC patients demonstrated significant improvements on measures of executive function and clinical state over the course of 12 months; verbal learning/memory performance generally remained stable. Improved cognitive performance was not correlated with MC use; however, clinical improvement was associated with higher CBD use. Analyses suggest cognitive improvements were associated with clinical improvement.

CONCLUSIONS

Study results extend previous pilot findings, indicating that MC patients may exhibit enhanced rather than impaired executive function over time. Future studies should examine distinctions between recreational and MC use to identify potential mechanisms related to cognitive changes and the role of clinical improvement.

Assessment of cognitive and psychomotor impairment, subjective effects, and blood THC concentrations following acute administration of oral and vaporized cannabis

BACKGROUND

Cannabis legalization is expanding, but there are no established methods for detecting cannabis impairment.

AIM

Characterize the acute impairing effects of oral and vaporized cannabis using various performance tests.

METHODS

Participants (N = 20, 10 men/10 women) who were infrequent cannabis users ingested cannabis brownies (0, 10, and 25 mg Δ-9-tetrahydrocannabinol, THC) and inhaled vaporized cannabis (0, 5, and 20 mg THC) in six double-blind outpatient sessions. Cognitive/psychomotor impairment was assessed with a battery of computerized tasks sensitive to cannabis effects, a novel test (the DRiving Under the Influence of Drugs, DRUID^®), and field sobriety tests. Blood THC concentrations and subjective drug effects were evaluated.

RESULTS

Low oral/vaporized doses did not impair cognitive/psychomotor performance relative to placebo but produced positive subjective effects. High oral/vaporized doses impaired cognitive/psychomotor performance and increased positive and negative subjective effects. The DRUID^® was the most sensitive test to cannabis impairment, as it detected significant differences between placebo and active doses within both routes of administration. Women displayed more impairment on the DRUID^® than men at the high vaporized dose only. Field sobriety tests showed little sensitivity to cannabis-induced impairment. Blood THC concentrations were far lower after cannabis ingestion versus inhalation. After inhalation, blood THC concentrations typically returned to baseline well before pharmacodynamic effects subsided.

CONCLUSIONS

Standard approaches for identifying impairment due to cannabis exposure (i.e. blood THC and field sobriety tests) have severe limitations. There is a need to identify novel biomarkers of cannabis exposure and/or behavioral tests like the DRUID^® that can reliably and accurately detect cannabis impairment at the roadside and in the workplace.

Are Sweet Dreams Made of These? Understanding the Relationship Between Sleep and Cannabis Use

Introduction: There is widespread literature on the interaction between cannabis use and sleep, yet the mechanisms that underlie this relationship are not well understood. Several factors lead to inconsistencies in this relationship suggesting a nuanced interaction between cannabis and sleep. An important question that remains to be addressed is the temporal relationship between disrupted sleep and cannabis use. This literature review summarizes the existing literature on the association between disrupted sleep and cannabis toward the goal of addressing the question of the chronology of these reported effects. Materials and Methods: We conducted a review of the literature using PubMed to summarize current knowledge on the association between cannabis use and sleep in humans. Results: We identified 31 studies on the association of cannabis use and sleep. The findings from these studies were mixed. Cannabis was associated with a variety of impacts on sleep ranging from beneficial effects, such as reduced sleep-onset latency, to negative outcomes, such as reduced sleep duration and suppressed rapid eye movement oscillations. The chronology of the interaction of cannabis and sleep was unclear, although much of the current literature focus on factors that modulate how cannabis impairs sleep after initial use. Conclusion: There was sufficient evidence to suggest that cannabis use alters circadian rhythms, and hence, negatively impacts sleep. The current literature is largely from studies utilizing self-report measures of sleep; thus, objective measures of sleep are needed. In addition, although there were no empirical studies on the temporal relationship between cannabis use and sleep, the majority of the literature focused on characterizing sleep impairment after cannabis use.

Cannabis and exercise: Effects of Δ9-tetrahydrocannabinol on preference and motivation for wheel-running in mice

Recent surveys have revealed close links between cannabis and exercise. Specifically, cannabis usage before and/or after exercise is an increasingly common habit primarily aimed at boosting exercise pleasure, motivation, and performance whilst facilitating post-exercise recovery. However, whether these beliefs reflect the true impact of cannabis on these aspects of exercise is unknown. This study has thus examined the effects of cannabis' main psychoactive ingredient, namely Δ⁹-tetrahydrocannabinol (THC), on (i) mouse wheel-running preference and performance and (ii) running motivation and seeking behaviour. Wheel-running preference and performance were investigated using a T-maze with free and locked wheels located at the extremity of either arm. Running motivation and seeking were assessed by a cued-running operant task wherein wheel-running was conditioned by nose poking. Moreover, because THC targets cannabinoid type 1 (CB₁) receptors, i.e. receptors previously documented to control running motivation, this study also assessed the role of these receptors in running preference, performance, and craving-like behaviour. Whilst acute blockade or genetic deletion of CB₁ receptors decreased running preference and performance in the T-maze, THC proved ineffective on either variable. The failure of THC to affect running variables in the T-maze extended to running motivation, as assessed by cued-running under a progressive ratio (PR) reinforcement schedule. This ineffectiveness of THC was not related to the treatment protocol because it successfully increased motivation for palatable food. Although craving-like behaviour, as indexed by a cue-induced reinstatement of running seeking, was found to depend on CB₁ receptors, THC again proved ineffective. Neither running motivation nor running seeking were affected when CB₁ receptors were further stimulated by increasing the levels of the endocannabinoid 2-arachidonoylglycerol. These results, which suggest that the drive for running is insensitive to the acute stimulation of CB₁ receptors, raise the hypothesis that cannabis is devoid of effect on exercise motivation. Future investigation using chronic administration of THC, with and without other cannabis ingredients (e.g. cannabidiol), is however required before conclusions can be drawn.

Pharmacokinetics of Cannabis Brownies: A Controlled Examination of Δ9-Tetrahydrocannabinol and Metabolites in Blood and Oral Fluid of Healthy Adult Males and Females

Oral cannabis products (a.k.a. "edibles") have increased in popularity in recent years. Most prior controlled pharmacokinetic evaluations of cannabis have focused on smoked cannabis and included males who were frequent cannabis users. In this study, 17 healthy adults (8 females), with no cannabis use in at least the past 2 months, completed 4 double-blind outpatient sessions where they consumed cannabis brownies containing Δ9-tetrahydrocannabinol (THC) doses of 0, 10, 25 or 50 mg. Whole blood and oral fluid specimens were collected at baseline and for 8 h post-brownie ingestion. Enzyme-linked immunosorbent assay (ELISA) and liquid chromatography-tandem mass spectrometry (LC-MS-MS) were used to measure THC and relevant metabolites. In whole blood, concentrations of THC and 11-hydroxy-THC (11-OH-THC) peaked 1.5-2 h after brownie consumption, decreased steadily thereafter, and typically returned to baseline within 8 h. Blood concentrations for 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH) and THCCOOH-glucuronide were higher than THC and 11-OH-THC and these metabolites were often still detected 8 h post-brownie consumption. Women displayed higher peak concentrations for THC and all metabolites in whole blood compared to men, at least partially owing to their lower body weight/body mass index. Detection of THC in oral fluid was immediate and appeared to reflect the degree of cannabis deposition in the oral cavity, not levels of THC circulating in the blood. THC concentrations were substantially higher in oral fluid than in blood; the opposite trend was observed for THCCOOH. Agreement between ELISA and LC-MS-MS results was high (i.e., over 90%) for blood THCCOOH and oral fluid THC but comparatively low for oral fluid THCCOOH (i.e., 67%). Following oral consumption of cannabis, THC was detected in blood much later, and at far lower peak concentrations, compared to what has been observed with inhaled cannabis. These results are important given the widespread use of toxicological testing to detect recent use of cannabis and/or to identify cannabis intoxication.

Cannabis, a cause for anxiety? A critical appraisal of the anxiogenic and anxiolytic properties

BACKGROUND

Cannabis has been documented for use in alleviating anxiety. However, certain research has also shown that it can produce feelings of anxiety, panic, paranoia and psychosis. In humans, Δ9-tetrahydrocannabinol (THC) has been associated with an anxiogenic response, while anxiolytic activity has been attributed mainly to cannabidiol (CBD). In animal studies, the effects of THC are highly dose-dependent, and biphasic effects of cannabinoids on anxiety-related responses have been extensively documented. A more precise assessment is required of both the anxiolytic and anxiogenic potentials of phytocannabinoids, with an aim towards the development of the 'holy grail' in cannabis research, a medicinally-active formulation which may assist in the treatment of anxiety or mood disorders without eliciting any anxiogenic effects.

OBJECTIVES

To systematically review studies assessing cannabinoid interventions (e.g. THC or CBD or whole cannabis interventions) both in animals and humans, as well as recent epidemiological studies reporting on anxiolytic or anxiogenic effects from cannabis consumption.

METHOD

The articles selected for this review were identified up to January 2020 through searches in the electronic databases OVID MEDLINE, Cochrane Central Register of Controlled Trials, PubMed, and PsycINFO.

RESULTS

Acute doses of CBD were found to reduce anxiety both in animals and humans, without having an anxiogenic effect at higher doses. Epidemiological studies tend to support an anxiolytic effect from the consumption of either  CBD or THC, as well as whole plant cannabis. Conversely, the available human clinical studies demonstrate a common anxiogenic response to THC (especially at higher doses).

CONCLUSION

Based on current data, cannabinoid therapies (containing primarily CBD) may provide a more suitable treatment for people with pre-existing anxiety or as a potential adjunctive role in managing anxiety or stress-related disorders. However, further research is needed to explore other cannabinoids and phytochemical constituents present in cannabis (e.g. terpenes) as anxiolytic interventions. Future clinical trials involving patients with anxiety disorders are warranted due to the small number of available human studies.

Δ9-Tetrahydrocannabinol (THC) impairs visual working memory performance: a randomized crossover trial

With the increasing prevalence of legal cannabis use and availability, there is an urgent need to identify cognitive impairments related to its use. It is widely believed that cannabis, or its main psychoactive component Δ9-tetrahydrocannabinol (THC), impairs working memory, i.e., the ability to temporarily hold information in mind. However, our review of the literature yielded surprisingly little empirical support for an effect of THC or cannabis on working memory. We thus conducted a study with three main goals: (1) quantify the effect of THC on visual working memory in a well-powered sample, (2) test the potential role of cognitive effects (mind wandering and metacognition) in disrupting working memory, and (3) demonstrate how insufficient sample size and task duration reduce the likelihood of detecting a drug effect. We conducted two double-blind, randomized crossover experiments in which healthy adults (N = 23, 23) performed a reliable and validated visual working memory task (the "Discrete Whole Report task", 90 trials) after administration of THC (7.5 and/or 15 mg oral) or placebo. We also assessed self-reported "mind wandering" (Exp 1) and metacognitive accuracy about ongoing task performance (Exp 2). THC impaired working memory performance (d = 0.65), increased mind wandering (Exp 1), and decreased metacognitive accuracy about task performance (Exp 2). Thus, our findings indicate that THC does impair visual working memory, and that this impairment may be related to both increased mind wandering and decreased monitoring of task performance. Finally, we used a down-sampling procedure to illustrate the effects of task length and sample size on power to detect the acute effect of THC on working memory.

Cannabidiol and Sports Performance: a Narrative Review of Relevant Evidence and Recommendations for Future Research

Cannabidiol (CBD) is a non-intoxicating cannabinoid derived from Cannabis sativa. CBD initially drew scientific interest due to its anticonvulsant properties but increasing evidence of other therapeutic effects has attracted the attention of additional clinical and non-clinical populations, including athletes. Unlike the intoxicating cannabinoid, Δ9-tetrahydrocannabinol (Δ9-THC), CBD is no longer prohibited by the World Anti-Doping Agency and appears to be safe and well-tolerated in humans. It has also become readily available in many countries with the introduction of over-the-counter "nutraceutical" products. The aim of this narrative review was to explore various physiological and psychological effects of CBD that may be relevant to the sport and/or exercise context and to identify key areas for future research. As direct studies of CBD and sports performance are is currently lacking, evidence for this narrative review was sourced from preclinical studies and a limited number of clinical trials in non-athlete populations. Preclinical studies have observed robust anti-inflammatory, neuroprotective and analgesic effects of CBD in animal models. Preliminary preclinical evidence also suggests that CBD may protect against gastrointestinal damage associated with inflammation and promote healing of traumatic skeletal injuries. However, further research is required to confirm these observations. Early stage clinical studies suggest that CBD may be anxiolytic in "stress-inducing" situations and in individuals with anxiety disorders. While some case reports indicate that CBD improves sleep, robust evidence is currently lacking. Cognitive function and thermoregulation appear to be unaffected by CBD while effects on food intake, metabolic function, cardiovascular function, and infection require further study. CBD may exert a number of physiological, biochemical, and psychological effects with the potential to benefit athletes. However, well controlled, studies in athlete populations are required before definitive conclusions can be reached regarding the utility of CBD in supporting athletic performance.

Oral Administration of Cannabis and Δ-9-tetrahydrocannabinol (THC) Preparations: A Systematic Review

Background and objective: Changes in cannabis legalization regimes in several countries have influenced the diversification of cannabis use. There is an ever-increasing number of cannabis forms available, which are gaining popularity for both recreational and therapeutic use. From a therapeutic perspective, oral cannabis containing Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) is a promising route of administration but there is still little information about its pharmacokinetics (PK) effects in humans. The purpose of this systematic review is to provide a general overview of the available PK data on cannabis and THC after oral administration. Materials and Methods: A search of the published literature was conducted using the PubMed database to collect available articles describing the PK data of THC after oral administration in humans. Results: The literature search yielded 363 results, 26 of which met our inclusion criteria. The PK of oral THC has been studied using capsules (including oil content), tablets, baked goods (brownies and cookies), and oil and tea (decoctions). Capsules and tablets, which mainly correspond to pharmaceutical forms, were found to be the oral formulations most commonly studied. Overall, the results reflect the high variability in the THC absorption of oral formulations, with delayed peak plasma concentrations compared to other routes of administration. Conclusions: Oral THC has a highly variable PK profile that differs between formulations, with seemingly higher variability in baked goods and oil forms. Overall, there is limited information available in this field. Therefore, further investigations are required to unravel the unpredictability of oral THC administration to increase the effectiveness and safety of oral formulations in medicinal use.

Cannabinoid modulation of corticolimbic activation to threat in trauma-exposed adults: a preliminary study

RATIONALE

Excessive fear and anxiety, coupled with corticolimbic dysfunction, are core features of stress- and trauma-related psychopathology, such as posttraumatic stress disorder (PTSD). Interestingly, low doses of ∆9-tetrahydrocannabinol (THC) can produce anxiolytic effects, reduce threat-related amygdala activation, and enhance functional coupling between the amygdala and medial prefrontal cortex and adjacent rostral cingulate cortex (mPFC/rACC) during threat processing in healthy adults. Together, these findings suggest the cannabinoid system as a potential pharmacological target in the treatment of excess fear and anxiety. However, the effects of THC on corticolimbic functioning in response to threat have not be investigated in adults with trauma-related psychopathology.

OBJECTIVE

To address this gap, the present study tests the effects of an acute low dose of THC on corticolimbic responses to threat in three groups of adults: (1) non-trauma-exposed healthy controls (HC; n = 25), (2) trauma-exposed adults without PTSD (TEC; n = 27), and (3) trauma-exposed adults with PTSD (n = 19).

METHODS

Using a randomized, double-blind, placebo-controlled, between-subjects design, 71 participants were randomly assigned to receive either THC or placebo (PBO) and subsequently completed a well-established threat processing paradigm during functional magnetic resonance imaging.

RESULTS

In adults with PTSD, THC lowered threat-related amygdala reactivity, increased mPFC activation during threat, and increased mPFC-amygdala functional coupling.

CONCLUSIONS

These preliminary data suggest that THC modulates threat-related processing in trauma-exposed individuals with PTSD, which may prove advantageous as a pharmacological approach to treating stress- and trauma-related psychopathology.

Pharmacodynamic dose effects of oral cannabis ingestion in healthy adults who infrequently use cannabis

BACKGROUND

Prior controlled cannabis research has mostly focused on smoked cannabis and predominantly included frequent cannabis users. Oral cannabis products ("edibles") make up a large and growing segment of the retail cannabis market. This study sought to characterize the pharmacodynamic effects of oral cannabis among infrequent cannabis users.

METHODS

Seventeen healthy adults who had not used cannabis for at least 60 days completed four experimental sessions in which they consumed a cannabis-infused brownie that contained 0, 10, 25, or 50 mg THC. Subjective effects, vital signs, cognitive/psychomotor performance, and blood THC concentrations were assessed before and for 8 h after dosing.

RESULTS

Relative to placebo, the 10 mg THC dose produced discriminable subjective drug effects and elevated heart rate but did not alter cognitive/psychomotor performance. The 25 and 50 mg THC doses elicited pronounced subjective effects and markedly impaired cognitive and psychomotor functioning compared with placebo. For all active doses, pharmacodynamic effects did not manifest until 30-60 min after ingestion, and peak effects occurred 1.5-3 h post-administration. Blood THC levels were significantly correlated with some pharmacodynamic drug effects, but were substantially lower than what is typically observed after cannabis inhalation.

CONCLUSION

Ingestion of oral cannabis dose-dependently altered subjective drug effects and impaired cognitive performance. Unlike inhaled forms of cannabis for which acute effects occur almost immediately, effects of oral cannabis were considerably delayed. In an era of legalization, education about the time course of drug effects for cannabis edibles is needed to facilitate dose titration and reduce acute overdose incidents.

The 'entourage effect' or 'hodge-podge hashish': the questionable rebranding, marketing, and expectations of cannabis polypharmacy

INTRODUCTION

The concept of a cannabis 'entourage effect' was first coined as a hypothetical afterthought in 1998. Since then, multiple scientific reviews, lay articles, and marketing campaigns have promoted the effect as a wholly beneficial manifestation of polypharmacy expected to modulate the therapeutic effects of cannabis and its derivatives. There is reason to wonder at the authenticity of such claims.

AREAS COVERED

A broad definition of the entourage effect is presented, followed by brief summaries of the nature of cannabis polypharmacy and the commonly cited contributing phytochemicals, with special attention to their attendant adverse effects. A critical analysis is then offered of the primary literature that is often portrayed as suggestive of the effect in existing reviews, with further studies being drawn from PubMed and Google Scholar searches. A final discussion questions the therapeutic value of the entourage effect and offers alternate perspectives on how it might be better interpreted.

EXPERT OPINION

Claims of a cannabis entourage effect invoke ill-defined and unsubstantiated pharmacological activities which are commonly leveraged toward the popularization and sale of ostensible therapeutic products. Overestimation of such claims in the scientific and lay literature has fostered their misrepresentation and abuse by a poorly regulated industry.

Do the effects of cannabis on the hippocampus and striatum increase risk for psychosis?

Cannabis use is associated with increased risk of psychotic symptoms and in a small number of cases it can lead to psychoses. This review examines the neurobiological mechanisms that mediate the link between cannabis use and psychosis risk. We use an established preclinical model of psychosis, the methylazoxymethanol acetate (MAM) rodent model, as a framework to examine if psychosis risk in some cannabis users is mediated by the effects of cannabis on the hippocampus, and this region's role in the regulation of mesolimbic dopamine. We also examine how cannabis affects excitatory neurotransmission known to regulate hippocampal neural activity and output. Whilst there is clear evidence that cannabis/cannabinoids can affect hippocampal and medial temporal lobe function and structure, the evidence that cannabis/cannabinoids increase striatal dopamine function is less robust. There is limited evidence that cannabis use affects cortical and striatal glutamate levels, but there are currently too few studies to draw firm conclusions. Future work is needed to test the MAM model in relation to cannabis using multimodal neuroimaging approaches.

Cannabinoid effects on responses to quantitative sensory testing among individuals with and without clinical pain: a systematic review

There has been an explosion of interest in the utility of cannabinoids as potential analgesics. This systematic review critically synthesizes the evidence for cannabinoid analgesic effects on quantitative sensory testing outcomes in both healthy adults and patients with chronic noncancer pain. Our systematic review protocol is preregistered on PROSPERO (CRD42018117367). An electronic search was made in PsycINFO, Cochrane, Google Scholar, Embase, and Pubmed of all literature published until August 2018. Of the 1217 studies found from the search, a total 39 placebo-controlled studies that met the eligibility criteria were synthesized for this study. Because of substantial heterogeneity of study designs, populations, cannabinoid compounds, and quantitative sensory testing outcomes, meta-analysis was not conducted. More consistent evidence of cannabinoid analgesia was observed for inhaled cannabis than synthetic cannabinoids. Analgesic effects were most commonly observed in tests of cold pain sensitivity, and hyperalgesic effects were most commonly observed in tests of electrical stimulation. Patterns of findings from studies with healthy subjects did not substantively differ from those with chronic noncancer pain. However, these observations are qualified by the high degree of inconsistency across studies and methodological heterogeneity. We offer recommendations for future studies to improve study rigor and reproducibility.

Exploring Cannabis and Alcohol Co-Use in Adolescents: A Narrative Review of the Evidence

Objective: Amidst the evolving policy surrounding cannabis legalization in the United States, cannabis use is becoming increasingly prevalent as perceptions of harm decrease, particularly among adolescents. Cannabis and alcohol are commonly used by adolescents and are often used together. However, developmental research has historically taken a "single substance" approach to examine the association of substance use and adolescent brain and behavior rather than examining co-(or poly-substance) use of multiple substances, such as cannabis and alcohol. Thus, the acute effects of cannabis and alcohol, and the impact of co-use of cannabis and alcohol on the adolescent brain, cognitive function and subsequent psychosocial outcomes remains understudied. This narrative review aims to examine the effects of cannabis and alcohol on adolescents across a number of behavioral and neurobiological outcomes. Methods: The PubMed and Google Scholar databases were searched for the last 10 years to identify articles reporting on acute effects of cannabis and alcohol administration, and the effects of cannabis and alcohol on neuropsychological, neurodevelopmental, neural (e.g., structural and functional neuroimaging), and psychosocial outcomes in adolescents. When adolescent data were not available, adult studies were included as support for potential areas of future direction in adolescent work. Results: Current studies of the impact of cannabis and alcohol on adolescent brain and behavior have yielded a complicated pattern. Some suggest that the use of cannabis in addition to alcohol during adolescence may have a "protective" effect, yielding neuropsychological and structural brain outcomes that are better than those for adolescents who use only alcohol. However, other adolescent studies suggest that cannabis and alcohol co-use is associated with negative health and social outcomes such as poorer academic performance and impaired driving. Conclusion: Variation in study methodologies, policy-level limitations and our limited understanding of the developmental neurobiological effects of cannabis preclude the straightforward interpretation of the existing data on adolescent cannabis and alcohol use. Further research on this topic is requisite to inform the development of effective intervention and prevention programs for adolescent substance users, which hinge on a more comprehensive understanding of how cannabis-and its intersection with alcohol-impacts the developing brain and behavior.

A novel phytocannabinoid isolated from Cannabis sativa L. with an in vivo cannabimimetic activity higher than Δ9-tetrahydrocannabinol: Δ9-Tetrahydrocannabiphorol

(-)-Trans-Δ9-tetrahydrocannabinol (Δ9-THC) is the main compound responsible for the intoxicant activity of Cannabis sativa L. The length of the side alkyl chain influences the biological activity of this cannabinoid. In particular, synthetic analogues of Δ9-THC with a longer side chain have shown cannabimimetic properties far higher than Δ9-THC itself. In the attempt to define the phytocannabinoids profile that characterizes a medicinal cannabis variety, a new phytocannabinoid with the same structure of Δ9-THC but with a seven-term alkyl side chain was identified. The natural compound was isolated and fully characterized and its stereochemical configuration was assigned by match with the same compound obtained by a stereoselective synthesis. This new phytocannabinoid has been called (-)-trans-Δ9-tetrahydrocannabiphorol (Δ9-THCP). Along with Δ9-THCP, the corresponding cannabidiol (CBD) homolog with seven-term side alkyl chain (CBDP) was also isolated and unambiguously identified by match with its synthetic counterpart. The binding activity of Δ9-THCP against human CB1 receptor in vitro (Ki = 1.2 nM) resulted similar to that of CP55940 (Ki = 0.9 nM), a potent full CB1 agonist. In the cannabinoid tetrad pharmacological test, Δ9-THCP induced hypomotility, analgesia, catalepsy and decreased rectal temperature indicating a THC-like cannabimimetic activity. The presence of this new phytocannabinoid could account for the pharmacological properties of some cannabis varieties difficult to explain by the presence of the sole Δ9-THC.

Delta-9-tetrahydrocannabinol potentiates fear memory salience through functional modulation of mesolimbic dopaminergic activity states

Chronic or acute exposure to delta-9-tetrahydrocannabinol (THC), the main psychoactive compound in cannabis, has been associated with numerous neuropsychiatric side-effects, including dysregulation of emotional processing and associative memory formation. Clinical and preclinical evidence suggests that the effects of THC are due to the ability to modulate mesolimbic dopamine (DA) activity states in the nucleus accumbens (NAc) and ventral tegmental area (VTA). Nevertheless, the mechanisms by which THC modulates mesolimbic DA function and emotional processing are not well understood. Using an olfactory associative fear memory procedure combined with in vivo neuronal electrophysiology, we examined the effects of direct THC microinfusions targeting the shell region of the NAc (NASh) and examined how THC may modulate the processing of fear-related emotional memory and concomitant activity states of the mesolimbic DA system. We report that intra-NASh THC dose-dependently potentiates the emotional salience of normally subthreshold fear conditioning cues. These effects were dependent upon intra-VTA transmission through GABAergic receptor mechanisms and intra-NASh DAergic transmission. Furthermore, doses of intra-NASh THC that potentiated fear memory salience were found to modulate intra-VTA neuronal network activity by increasing the spontaneous firing and bursting frequency of DAergic neurones whilst decreasing the activity levels of a subpopulation of putative GABAergic VTA neurones. These findings demonstrate that THC can act directly in the NASh to modulate mesolimbic activity states and induce disturbances in emotional salience and memory formation through modulation of VTA DAergic transmission.

Exploring the munchies: An online survey of users' experiences of cannabis effects on appetite and the development of a Cannabinoid Eating Experience Questionnaire

BACKGROUND

Cannabis intoxication is commonly reported to increase appetite and enhance appreciation of food (the 'munchies'). These effects are attributed to activation of the endocannabinoid system. However, the psychological changes that underlie these phenomena are under-researched. We report here the results of an extensive online survey of cannabis users with an exploratory Cannabinoid Eating Experience Questionnaire (CEEQ).

METHOD

Frequent cannabis users completed a 46-item questionnaire about their eating behaviour under the influence of cannabis. An English-speaking sample (n=591) provided data for the initial exploratory validation of the scale. A second Dutch-language survey (n=163) was used for confirmatory factor analysis. Test-retest reliability was based on a third English-speaking sample (n=40) who completed the revised, 28-item CEEQ twice across 2 weeks.

RESULTS

Principal components analysis provided a two-factor solution. Factor 1 (hedonic) comprised 14 items that related primarily to the enjoyment and altered sensory aspects of eating. Factor 2 (appetitive) comprised a further 14 items related to motivational factors that instigate or promote eating. The two-factor structure was supported by confirmatory factor analysis. Both the hedonic and appetitive subscales had good internal reliability (α=0.92 for each subscale, in two independent samples). Good test-retest reliability was obtained for the revised 28-item questionnaire (ps<.01 for Total CEEQ and each subscale).

CONCLUSION

The Cannabinoid Eating Experience Questionnaire provided a valid, reliable assessment of the psychological features of cannabis-induced alterations to appetite. Our data confirm that cannabis principally influences the motivational factors that lead to the initiation of eating and the hedonic factors implicated in maintaining eating.

Developing a phone-based measure of impairment after acute oral ∆9-tetrahydrocannabinol

BACKGROUND

Acute consumption of cannabis or its primary psychoactive ingredient ∆9-tetrahydrocannabinol has been shown to impair memory, reaction time, time perception, and attention. However, it is difficult to measure these impairments in a brief test that can be used in a non-laboratory setting.

AIMS

We aim to develop and validate a prototype for a mobile phone application to measure ∆9-tetrahydrocannabinol-induced cognitive impairment.

METHODS

We conducted two double-blind, within-subjects studies examining impairments after oral doses of ∆9-tetrahydrocannabinol (0, 7.5, 15 mg) using both standardized computer-based tasks and our novel phone-based tasks. The tasks measured cognitive speed, reaction time, fine motor ability, and working memory and, in the second study, time perception. Study 1 (n=24) provided initial data, and Study 2 (n=24) was designed to refine the measures. In both studies, healthy non-daily cannabis users participated in three four-hour experimental sessions in which they received capsules containing ∆9-tetrahydrocannabinol (7.5, 15 mg) or placebo. Subjective and cardiovascular measures were obtained at regular intervals, and at the time of peak drug effect subjects completed both standardized, computer-based and brief, phone-based tasks.

RESULTS

∆9-Tetrahydrocannabinol-induced impairment was detected on most of the computer tasks, but was not evident on most of the phone tasks.

CONCLUSIONS

The phone tasks were brief, to facilitate use in a non-laboratory setting, but it is likely that this made them less sensitive to the impairing effects of ∆9-tetrahydrocannabinol. These findings confirm that ∆9-tetrahydrocannabinol impairs performance on several tasks at two recreationally relevant doses, but raises question about the feasibility of designing a phone application as a sensitive field sobriety test for cannabis.

Chronic cannabis use and circulating biomarkers of neural health, stress, and inflammation in physically active individuals

Previous research has associated cannabis use with altered circulating neurotrophins and biomarkers of immune health, but these relationships have yet to be fully explored in physically active individuals. The specific aim of this study was to explore the relationships between biomarkers of neural health: nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF), immune health: interleukin 6 (IL-6), C-reactive protein (CRP), and cortisol, as well as the presence of depression, in physically active cannabis users (CU) and nonusers (NU). Male and female participants (N = 30; CU, n = 15, NU, n = 15) provided intravenous blood samples and underwent assessment of body composition, maximal oxygen consumption, and depression (Beck Depression Inventory-II (BDI-II)). Samples were analyzed for concentrations of NGF, BDNF, IL-6, CRP, and cortisol using ELISAs. CU and NU were compared using an unpaired t test. Pearson's correlation and multiple linear regression were used to evaluate relationships among variables. There were no significant differences in body size or composition, maximal oxygen consumption, total BDI-II Score, concentrations of NGF, IL-6, CRP, or cortisol between groups. BDNF was significantly lower in CU compared with NU (p = 0.02), with a significant negative relationship between BDNF and CRP (p = 0.02). Mean concentrations of CRP placed CU at higher risk for cardiovascular disease compared with NU. Total BDI-II score negatively correlated with BDNF (p = 0.02) and positively correlated with CRP (p = 0.02). Novelty Plasma BDNF was significantly lower in physically active cannabis users compared with NU. CU were classified at moderate risk for cardiovascular disease based on average circulating CRP compared with low risk for NU.

Liprin alfa 2 gene expression is increased by cannabis use and associated with neuropsychological function

The relation of heavy cannabis use with decreased neuropsychological function has frequently been described but the underlying biological mechanisms are still largely unknown. This study investigates the relation of cannabis use with genome wide gene expression and subsequently examines the relations with neuropsychological function. Genome-wide gene expression in whole blood was compared between heavy cannabis users (N = 90) and cannabis naïve participants (N = 100) that were matched for psychotic like experiences. The results were validated using quantitative real-time PCR. Psychotic like experiences were assessed using the Comprehensive Assessment of Psychotic Experiences (CAPE). Neuropsychological function was estimated using four subtasks of the Wechsler Adult Intelligence Scale (WAIS). Subsequent in vitro studies in monocytes and a neuroblastoma cell line investigated expression changes in response to two major psychotropic components of cannabis; tetrahydrocannabinol (THC) and cannabidiol (CBD). mRNA expression of Protein Tyrosine Phosphatase Receptor Type F Polypeptide-Interacting-Protein Alpha-2 (PPFIA2) was significantly higher in cannabis users (LogFold Change 0.17) and confirmed by qPCR analysis. PPFIA2 expression level was negatively correlated with estimated intelligence (B=-22.9, p = 0.002) also in the 100 non-users (B=-28.5, p = 0.037). In vitro exposure of monocytes to CBD led to significant increase in PPFIA2 expression. However, exposure of monocytes to THC and neuroblastoma cells to THC or CBD did not change PPFIA2 expression. Change in PPFIA2 gene expression in response to cannabinoids is a putative mechanism by which cannabis could influence neuropsychological functions. The findings warrant further exploration of the role of PPFIA2 in cannabis induced changes of neuropsychological function, particularly in relation to CBD.

Alcohol Interaction with Cocaine, Methamphetamine, Opioids, Nicotine, Cannabis, and γ-Hydroxybutyric Acid

Millions of people around the world drink alcoholic beverages to cope with the stress of modern lifestyle. Although moderate alcohol drinking may have some relaxing and euphoric effects, uncontrolled drinking exacerbates the problems associated with alcohol abuse that are exploding in quantity and intensity in the United States and around the world. Recently, mixing of alcohol with other drugs of abuse (such as opioids, cocaine, methamphetamine, nicotine, cannabis, and γ-hydroxybutyric acid) and medications has become an emerging trend, exacerbating the public health concerns. Mixing of alcohol with other drugs may additively or synergistically augment the seriousness of the adverse effects such as the withdrawal symptoms, cardiovascular disorders, liver damage, reproductive abnormalities, and behavioral abnormalities. Despite the seriousness of the situation, possible mechanisms underlying the interactions is not yet understood. This has been one of the key hindrances in developing effective treatments. Therefore, the aim of this article is to review the consequences of alcohol's interaction with other drugs and decipher the underlying mechanisms.

Δ9-Tetrahydrocannabinol at Retrieval Drives False Recollection of Neutral and Emotional Memories

BACKGROUND

It is well established that the main psychoactive constituent of cannabis, Δ⁹-tetrahydrocannabinol (THC), impairs episodic memory encoding and modulates emotional processing, but little is known about the impact of THC during the retrieval of emotional episodic memories. With the rise of cannabis to treat medical conditions, including those characterized by emotional and episodic memory disturbances, there is an urgent need to determine the effects of THC on memory accuracy and distortion. Here, we report the first study investigating the effects of THC during retrieval of neutral and emotional episodic memories.

METHODS

Using a double-blind, placebo-controlled, within-subjects design, healthy volunteers (N = 23) viewed negative, neutral, and positive pictures (emotional memory task) and lists of semantically related words (false memory task). Forty-eight hours later, participants ingested a capsule containing either THC (15 mg) or placebo and completed tasks to test their memories for the previously studied pictures and words.

RESULTS

THC during retrieval did not reduce the number of correct responses to studied items. Instead, it robustly increased false recollection on both the emotional memory and false memory tasks. This effect was found for both neutral and emotional items.

CONCLUSIONS

These findings show that THC has adverse effects during memory retrieval, distorting both neutral and emotional memories. Coupled with THC's known effects during encoding, these new retrieval findings are important in light of the spreading acceptance of cannabis.

The neuropsychopharmacology of cannabis: A review of human imaging studies

The laws governing cannabis are evolving worldwide and associated with changing patterns of use. The main psychoactive drug in cannabis is Δ⁹-tetrahydrocannabinol (THC), a partial agonist at the endocannabinoid CB₁ receptor. Acutely, cannabis and THC produce a range of effects on several neurocognitive and pharmacological systems. These include effects on executive, emotional, reward and memory processing via direct interactions with the endocannabinoid system and indirect effects on the glutamatergic, GABAergic and dopaminergic systems. Cannabidiol, a non-intoxicating cannabinoid found in some forms of cannabis, may offset some of these acute effects. Heavy repeated cannabis use, particularly during adolescence, has been associated with adverse effects on these systems, which increase the risk of mental illnesses including addiction and psychosis. Here, we provide a comprehensive state of the art review on the acute and chronic neuropsychopharmacology of cannabis by synthesizing the available neuroimaging research in humans. We describe the effects of drug exposure during development, implications for understanding psychosis and cannabis use disorder, and methodological considerations. Greater understanding of the precise mechanisms underlying the effects of cannabis may also give rise to new treatment targets.

The adverse health effects and harms related to marijuana use: an overview review

BACKGROUND

With impending marijuana legislation in Canada, a broad understanding of the harms associated with marijuana use is needed to inform the clinical community and public, and to support evidence-informed public policy development. The purpose of the review was to synthesize the evidence on adverse health effects and harms of marijuana use.

METHODS

We searched MEDLINE, The Cochrane Database of Systematic Reviews, Embase, PsycINFO, the Cumulative Index to Nursing and Allied Health Literature, and the Health Technology Assessment Database from the inception of each database to May 2018. Given that systematic reviews evaluating one or other specific harm have been published, this is an overview review with the primary objective of assessing a health effect or harm. Data on author, country and year of publication, search strategy and results, and outcomes were extracted. Quality was assessed using the AMSTAR (A Measurement Tool to Assess Systematic Reviews) checklist.

RESULTS

The final analysis included 68 reviews. Evidence of harm was reported in 62 reviews for several mental health disorders, brain changes, cognitive outcomes, pregnancy outcomes and testicular cancer. Inconclusive evidence was found for 20 outcomes (some mental health outcomes, other types of cancers and all-cause mortality). No evidence of harm was reported for 6 outcomes.

INTERPRETATION

Harm was associated with most outcomes assessed. These results should be viewed with concern by physicians and policy-makers given the prevalence of use, the persistent reporting of a lack of recognition of marijuana as a possibly harmful substance and the emerging context of legalization for recreational use.

Cannabis and cannabinoid drug development: evaluating botanical versus single molecule approaches

Accumulating evidence suggests that the endocannabinoid system is a promising target for the treatment of a variety of health conditions. Two paths of cannabinoid drug development have emerged. One approach is focused on developing medications that are directly derived from the cannabis plant. The other utilizes a single molecule approach whereby individual phytocannabinoids or novel cannabinoids with therapeutic potential are identified and synthesized for pharmaceutical development. This commentary discusses the unique challenges and merits of botanical vs single molecule cannabinoid drug development strategies, highlights how both can be impacted by legalization of cannabis via legislative processes, and also addresses regulatory and public health considerations that are important to consider as cannabinoid medicine advances as a discipline.

Acute induction of anxiety in humans by delta-9-tetrahydrocannabinol related to amygdalar cannabinoid-1 (CB1) receptors

Use of Cannabis, the most widely used illicit drug worldwide, is associated with acute anxiety, and anxiety disorders following regular use. The precise neural and receptor basis of these effects have not been tested in man. Employing a combination of functional MRI (fMRI) and positron emission tomography (PET), we investigated whether the effects of delta-9-tetrahydrocannabinol (delta-9-THC), the main psychoactive ingredient of cannabis, on anxiety and on amygdala response while processing fearful stimuli were related to local availability of its main central molecular target, cannabinoid-1 (CB1) receptors in man. Fourteen healthy males were studied with fMRI twice, one month apart, following an oral dose of either delta-9-THC (10 mg) or placebo, while they performed a fear-processing task. Baseline availability of the CB1 receptor was studied using PET with [11C]MePPEP, a CB1 inverse agonist radioligand. Relative to the placebo condition, delta-9-THC induced anxiety and modulated right amygdala activation while processing fear. Both these effects were positively correlated with CB1 receptor availability in the right amygdala. These results suggest that the acute effects of cannabis on anxiety in males are mediated by the modulation of amygdalar function by delta-9-THC and the extent of these effects are related to local availability of CB1 receptors.