Interactions between nicotine and drugs of abuse: a review of preclinical findings

The effects of alcohol use on smoking cessation treatment with nicotine replacement therapy: An observational study

INTRODUCTION

Concurrent users of tobacco and alcohol are at greater risk of harm than use of either substance alone. It remains unclear how concurrent tobacco and alcohol use affects smoking cessation across levels of alcohol use and related problems. This study assessed the relationship between smoking cessation and levels of alcohol use problems.

METHODS

59,018 participants received nicotine replacement therapy through a smoking cessation program. Alcohol use and related symptoms were assessed using the Alcohol Use Disorders Identification Test (AUDIT-10) and the AUDIT-Concise (AUDIT-C). The primary outcome was 7-day point prevalence cigarette abstinence (PPA) at 6-month follow-up. We evaluated the association between alcohol use (and related problems) and smoking cessation using descriptive methods and mixed-effects logistic regression.

RESULTS

7-day PPA at 6-months was lower in groups meeting hazardous alcohol consumption criteria, with the lowest probability of smoking abstinence observed in the highest risk group. The probability of successful tobacco cessation fell with increasing levels of alcohol use and related problems. Adjusted predicted probabilities were 30.3 (95 % CI = 29.4, 31.1) for non-users, 30.2 (95 % CI = 29.4, 31.0) for low-risk users, 29.0 (95 % CI = 28.1, 29.9) for those scoring below 8 on the AUDIT-10, 27.3 (95 % CI = 26.0, 28.6) for those scoring 8-14, and 24.4 (95 % CI = 22.3, 26.5) for those scoring 15 or higher.

CONCLUSION

Heavy, hazardous alcohol use is associated with lower odds of successfully quitting smoking compared to low or non-use of alcohol. Targeting alcohol treatment to this group may improve tobacco cessation outcomes.

Predicting Time to Return to Cannabis Use After a Cessation Attempt: Impact of Cumulated Exposure to Nicotine-Containing Products

Objective: Cannabis is frequently co-used with tobacco/nicotine products, especially among young adults. Little is known about the effects of this co-use on cannabis cessation outcomes. Within a sample of young adults using cannabis frequently (current use of ≥5 days/week in the past 3 months), this study aimed to (a) document sources of exposure to tobacco/nicotine products, whether used simultaneously with cannabis or on different occasions, (b) examine if the level of cumulated exposure to tobacco/nicotine (self-reported or from biochemical testing) could predict time to cannabis lapse during a cannabis abstinence period, and (c) explore the relationship between nicotine/tobacco exposure and time to cannabis lapse according to tobacco cigarette smoking status. Method: Urine cotinine measures and self-reported data on use of different tobacco/nicotine products, collected from 32 participants (aged 19 to 23), were analyzed to predict time to lapse during a 2-week period of attempted abstinence from cannabis, controlling for cannabis dependence and sex. Results: Half of participants (56.3%) used at least one tobacco/nicotine product. Higher urine cotinine, representing higher cumulated tobacco/nicotine exposure, was related to a higher risk of lapsing (Hazard Ratio [HR] = 1.64; 95%CI [1.04, 2.58]). The risk of lapsing was even higher ([HR] = 3.46; 95%CI [1.17, 10.25]) among heavily tobacco/nicotine exposed (>600 ng/mL, urine cotinine) participants than among unexposed (<50 ng/mL) or lightly/moderately exposed (50-600 ng/mL) participants. Among those smoking cigarettes (solely or in combination with other products), there was no relation between cotinine level and time to lapse, likely due to a reduced variability in abstinence probability and a high likelihood of lapse observed for higher cotinine levels, mainly achieved by cigarette use. Conclusions: With a rapidly changing landscape of tobacco/nicotine use, our results underscore the need to consider all sources of tobacco/nicotine exposure to fully understand the specific and cumulative contributions of tobacco/nicotine to cannabis cessation outcomes.

Classification of patterns of tobacco and cannabis co-use based on temporal proximity: A qualitative study among young adults

PURPOSE

Co-use of tobacco and cannabis is a common and complex behavior. The lack of harmonized measures of co-use yields confusion and inconsistencies in synthesizing evidence about the health effects of co-use. We aimed to classify co-use patterns based on temporal proximity and describe preferred products and motives for each pattern in order to improve co-use surveillance.

METHODS

We conducted semi-structured interviews in a sample of 34 young adults (Mage = 22.8 years, 32.4 % female) during 2017-2019 in California, USA. We employed a qualitative thematic analysis to identify timing, reasons, and contexts for tobacco and cannabis co-use and classify co-use patterns.

RESULTS

Four emergent patterns of co-use with increasing temporal proximity between tobacco use and cannabis use were: Same-month different-day co-use (Pattern 1); Same-day different-occasion co-use (Pattern 2); Same-occasion sequential co-use (Pattern 3); and Same-occasion simultaneous co-use (Pattern 4). Participants used various product combinations within each pattern. Similar motives for all patterns were socialization, product availability, and coping with stress/anxiety. Unique motive for temporally distant patterns (Patterns 1 and 2) was seeking substance-specific effects (e.g., stimulant effect from nicotine, relaxation effects from cannabis), while unique motives for temporally close patterns (Patterns 3 and 4) were seeking combined effects from both substances (e.g., more intense psychoactive effects, mitigating cannabis adverse effects) and behavioral trigger (e.g., cannabis use triggers tobacco use).

CONCLUSIONS

Our classification of co-use patterns can facilitate consistency for measuring co-use and assessing its health impacts. Future research should also measure product types and motives for different patterns to inform intervention efforts.

Amphetamine use disorder is associated with striatum hypoactivation during anticipation of loss and reward

BACKGROUND

Dysregulated ventral striatum function has been proposed as one important process occurring in individuals with substance use disorder. This study investigates the role of altered reward and loss anticipation, which is an important component of impaired decision-making, impulsivity, and vulnerability to relapse in individuals with amphetamine use disorder (AMP).

AIMS

To determine whether AMP is associated with blunted striatum, prefrontal cortex, and insula signals during win and loss anticipation.

METHODS

Participants with and without AMP (AMP+ n = 46, AMP- n = 90) from the Tulsa 1000 study completed a monetary incentive delay (MID) task during functional magnetic resonance imaging.

RESULTS

Group main effects indicated that: (1) AMP+ exhibited lower bilateral caudate/putamen and left nucleus accumbens signal than AMP- across anticipation of wins and losses; and (2) AMP+ showed slower reaction times than AMP- during loss anticipation. Group*condition interactions demonstrated that AMP+ exhibited greater right amygdala signal than AMP- while anticipating large wins, a pattern that reversed when anticipating small losses. Left caudate/putamen attenuations in AMP+ during small loss anticipation were also evident. Groups did not differ in prefrontal or insula signals.

CONCLUSIONS

AMP+ individuals have altered neural processing and response patterns during reward and loss anticipation, potentially reflecting impairments in dopamine function, which may influence their decision-making and reactions to different win/loss scenarios. These findings help to explain why AMP+ have difficulty with decision-making and exhibit a heightened focus on immediate rewards or punishments.

Moral Injury is a Risk Factor for Substance Use and Suicidality Among US Military Veterans with and without Traumatic Brain Injury

A national survey of United States veterans was conducted, yielding 252 veterans with Traumatic Brain Injury (TBI) and 1235 veterans without TBI. Participants were asked questions about moral injury, suicidality, substance use, and other sociodemographic variables. Multivariable linear regression analysis was used to examine the previously described relationships. Increasing severity of moral injury was associated with higher scores on the substance use tool (b = 0.02, p = 0.04), although the magnitude of effect was not different from those without TBI (Z = - 0.57, p = 0.72). Increasing severity of moral injury was positively associated with suicidal behavior scores (b = 0.10, p < 0.01). The strength of this relationship was stronger in veterans with TBI than those without TBI (Z = 1.78, p = 0.04). Rehabilitation programs that treat veterans for TBI may need to consider the evaluation of moral injury given its association with adverse events in this population.

Incidence of opioid misuse by cigarette smoking status in the United States

BACKGROUND

The combination of opioid misuse and cigarette smoking contributes to increased morbidity and mortality compared to each substance use alone. We estimated the incidence of opioid misuse for persons who currently or formerly smoked versus never smoked.

METHODS

Data came from the 2015-2020 National Surveys on Drug Use and Health cross-sectional surveys of US civilians aged 12+ (n = 315,661). Weighted opioid misuse incidence and average time between cigarette use initiation and opioid misuse initiation were calculated annually by smoking status. Logistic regression models tested time trends in incidence by smoking status.

RESULTS

Overall, 0.75% of persons initiated opioid misuse per year; opioid misuse incidence was 1.35% for those who currently smoked cigarettes, 0.54% for those who formerly smoked, and 0.67% for those who never smoked. For persons who currently smoked and misused opioids (1.50%), 95.08% smoked prior to opioid use. The average time between smoking followed by opioid misuse was 12.93 years and for opioid misuse followed by smoking was 4.36 years. Persons who currently smoked were more likely to initiate opioid misuse than those who had never smoked (AOR = 1.81, 95% CI: 1.60, 2.06). There was a decrease in the opioid misuse incidence over time (AOR = 0.90; 95% CI: 0.85, 0.92), which did not differ by smoking status.

CONCLUSIONS

Persons who currently smoked cigarettes, relative to those who never smoked, were more likely to initiate opioid misuse. As most individuals smoked before opioid misuse, it may be useful for primary prevention efforts to decrease opioid misuse initiation by focusing on smoking status.

Assessment of ethanol and nicotine interactions using a reinforcer demand modeling with grouped and individual levels of analyses in a long-access self-administration model using male rats

Previous reports have indicated the reciprocal effects of nicotine and ethanol on their rewarding and reinforcing properties, but studies using methodological approaches resembling substance use in vulnerable populations are lacking. In our study, rats first self-administered ethanol, and their sensitivity to ethanol's reinforcing effects was assessed using a reinforcer demand modeling approach. Subsequently, rats were equipped with intravenous catheters to self-administer nicotine, and their sensitivity to nicotine's reinforcing effects was evaluated using the same approach. In the final phase, rats were allowed to self-administer ethanol and nicotine concurrently, investigating the influence of one substance on the rate of responding for the other substance. Group analyses revealed notable differences in demand among sucrose, sweetened ethanol, and ethanol-alone, with sucrose demonstrating the highest demand and ethanol-alone exhibiting greater sensitivity to changes in cost. At the individual level, our study finds significant correlations between rats' demand for sucrose and sweetened ethanol, suggesting parallel efforts for both substances. Our individual data also suggest interconnections in the elasticity of demand for sweetened ethanol and ethanol-alone, as well as a potential relationship in price response patterns between ethanol and nicotine. Furthermore, concurrent self-administration of ethanol and nicotine at the group level displayed reciprocal effects, with reduced responding for nicotine in the presence of ethanol and increased responding for ethanol in the presence of nicotine. This study provides valuable insights into modeling the co-use of ethanol and nicotine and assessing their interaction effects using reinforcer demand modeling and concurrent self-administration or noncontingent administration tests. These findings contribute to our understanding of the complex interplay between ethanol and nicotine and have implications for elucidating the underlying mechanisms involved in polydrug use.

Psychostimulant Misuse Among American Indian, Alaskan Native, or Native Hawaiian College Students in the U.S. From 2015 to 2019

Introduction

This study examines factors associated with psychostimulant misuse, including polysubstance use and social factors, among the understudied American Indian/Alaska Native/Native Hawaiian (AI/AN/NH) college student population.

Methods

Data were from the 2015 to 2019 American College Health Association-National College Health Assessment IIc (ACHA-NCHA IIc) survey. Multivariable logistic regression models and odds ratios were used to estimate associations between psychostimulant misuse and potential risk and protective factors among AI/AN/NH college students, including licit and illicit substance use, social support, relationship factors, exposure to violence or abuse, mental health symptoms, drug and alcohol education, and sample demographics.

Results

Opioid misuse among AI/AN/NH college students significantly increased the odds of using psychostimulants. Specifically, for cocaine use, the adjusted odds ratio (aOR) was 3.17 with a 95% confidence interval (C.I.) of 2.17 to 4.63; for methamphetamine use, the aOR was 38.87 (95% C.I. 19.24-78.52). For amphetamine misuse among non-Tobacco users, the aOR was 5.47 (95% C.I. 3.49-8.55), while among Tobacco users, the aOR was 2.65 (95% C.I. 2.07-3.41). For cocaine and other stimulant misuse, the aOR was 3.64 (95% C.I. 2.30-5.67). Additionally, the use of other types of licit and illicit substances was associated with greater odds of psychostimulant use and misuse. Conversely, factors such as age, living on campus, and residing in parental/guardian housing were linked with lower odds of psychostimulant use and misuse.

Conclusion

Substance use prevention and treatment interventions targeting AI/AN/NH college students should address polysubstance use, including the combined use of opioids and psychostimulants. Substance use interventions should not be siloed to focus narrowly on single substances but rather should leverage potential protective factors against substance use, such as promoting supportive campus and family living conditions and other social support networks, in broad efforts to reduce multiple forms of substance use among AI/AN/NH students.

Postmortem toxicology findings from the Camden Opioid Research Initiative

The United States continues to be impacted by decades of an opioid misuse epidemic, worsened by the COVID-19 pandemic and by the growing prevalence of highly potent synthetic opioids (HPSO) such as fentanyl. In instances of a toxicity event, first-response administration of reversal medications such as naloxone can be insufficient to fully counteract the effects of HPSO, particularly when there is co-occurring substance use. In an effort to characterize and study this multi-faceted problem, the Camden Opioid Research Initiative (CORI) has been formed. The CORI study has collected and analyzed post-mortem toxicology data from 42 cases of decedents who expired from opioid-related toxicity in the South New Jersey region to characterize substance use profiles. Co-occurring substance use, whether by intent or through possible contamination of the illicit opioid supply, is pervasive among deaths due to opioid toxicity, and evidence of medication-assisted treatment is scarce. Nearly all (98%) of the toxicology cases show the presence of the HPSO, fentanyl, and very few (7%) results detected evidence of medication-assisted treatment for opioid use disorder, such as buprenorphine or methadone, at the time of death. The opioid toxicity reversal drug, naloxone, was detected in 19% of cases, but 100% of cases expressed one or more stimulants, and sedatives including xylazine were detected in 48% of cases. These results showing complex substance use profiles indicate that efforts at mitigating the opioid misuse epidemic must address the complications presented by co-occurring stimulant and other substance use, and reduce barriers to and stigmas of seeking effective medication-assisted treatments.

A determination of the aerosolization efficiency of drugs of abuse in a eutectic mixture with nicotine in electronic cigarettes

Eutectic mixtures can be formed by adding drugs other than nicotine (DOTNs) to nicotine-based e-liquids in electronic cigarettes (e-cigarettes). Thus, the interaction between nicotine e-liquids and DOTNs must be evaluated. Presented is the change in e-cigarette aerosolization of nicotine and methadone alone versus a 1:1 nicotine:methadone mixture to evaluate the possible formation of a eutectic mixture that can result in an increase of drug delivery. E-liquids were prepared in-house using 1:1 propylene glycol (PG):vegetable glycerin (VG) as a base plus nicotine, methadone hydrochloride, or 1:1 nicotine:methadone hydrochloride. The e-liquids were aerosolized via an automated vaping machine using parameters adopted from the Cooperation Centre for Scientific Research Relative to Tobacco (CORESTA) E-cigarette Task Force method. Drug recovery was determined by capturing the aerosol from 15 puffs generated by the e-cigarette. Concentrations of nicotine and methadone aerosolized were determined by gas chromatography-mass spectrometry using nicotine (n = 3), methadone (n = 3), and combined nicotine/methadone e-liquids (n = 3), each prepared in-house at 12 mg/ml. The concentration of nicotine and methadone in 15 puffs of the single drug e-liquids were determined to be 1.60 ± 0.20 and 2.67 ± 0.12 mg, respectively. The concentration of nicotine and methadone in 15 puffs of the multidrug e-liquid were determined to be 3.66 ± 0.49 and 3.65 ± 0.10 mg, respectively. The single nicotine and methadone e-liquids had recoveries of 70 ± 0.1% and 84 ± 0.1%, respectively. In the 1:1 mixture, the recovery of both drugs increased. The development of a eutectic mixture can promote aerosolization of the drug and deliver a greater dose to the user.

Patterns and perceptions of nicotine use among U.S. adolescents and young adults receiving medication treatment for opioid use disorder

Nicotine use among U.S. youth is cause for concern, as previous studies have shown that nicotine use in adolescence increases the risk of developing substance use disorders later in life. This exploratory study aimed to understand patterns of nicotine use and perceptions of various nicotine products among adolescents and young adults (AYA) receiving medication treatment for opioid use disorder (MOUD). We administered an adapted version of the National Youth Tobacco Survey via REDCap to AYA (n = 32) receiving outpatient care in the Medication-Assisted Treatment of Addiction at Nationwide Children's Hospital in Columbus, Ohio, U.S.A. Thirty (97%) participants had tried a combustible cigarette and 27 (90%) had tried an electronic cigarette. By age 13, nineteen (61%) participants had tried combustible cigarettes and eight (25%) had tried opioids. Twenty-two (71%) participants reported smoking combustible cigarettes every day for the past 30 days, and 15 (48%) reported smoking more than 10 cigarettes per day on average. Only ten (32%) participants reported e-cigarette use in the last 30 days. Participants universally agreed that tobacco products are dangerous, and twenty (67%) current tobacco users reported that they planned to quit in the next year. Nicotine use patterns among AYA receiving MOUD differ from that previously shown in the general population, primarily by high prevalence of nicotine use in early adolescence and high current combustible cigarette use. Interventions such as universal screening for nicotine use before age 13 and tailored smoking cessation programs for AYA with OUD may help optimize care for these individuals.

Comparing cigarette-cue attentional bias between people with HIV/AIDS and people with opioid use disorder who smoke

Background

Special populations like people living with HIV/AIDS (PLWHA) and people with opioid use disorder (OUD) smoke tobacco cigarettes at rates three to four times greater than the general population. Patients with tobacco use disorder exhibit attentional bias (AB) for cigarette cues. Eye tracking can quantify this bias by measuring fixation time (FT) on cigarette and matched neutral cues, to calculate an AB score. Although previous studies have measured this bias in people who smoke without any other comorbid conditions, no study, to our knowledge, has measured or compared this bias in special populations.

Methods

We performed exploratory analyses on eye tracking data collected in two separate randomized clinical trials (RCTs) (NCT05049460, NCT05295953). We compared FT and cigarette-cue AB score (measured by subtracting FT on neutral cues from FT on cigarette cues) between PLWHA and people with OUD who smoke, using a visual probe task and Tobii Pro Fusion eye tracker. We used two cigarette cue types, one encompassing people smoking cigarettes and the other consisting of cigarette paraphernalia. We used two cue presentation times, 1000 and 2000 milliseconds (ms).

Results

Cues of people smoking cigarettes elicited greater AB than cues of cigarette paraphernalia across both subject groups when cues were presented for 2000 ms, but not 1000 ms. PLWHA who smoke exhibited greater AB for cues of people smoking cigarettes than cigarette paraphernalia when presented for 2000 ms compared to people with OUD who smoke.

Conclusion

We use cigarette-cue AB to quantify craving and cigarette consumption in two populations smoking at elevated rates. The addition of social cues potentiates cigarette cue AB, based on cue type and stimulus presentation time. Understanding the neurobiology of this relationship can help design novel smoking cessation treatments that target AB and prevent relapse in these populations with suboptimal response to smoking cessation treatments.

Trial registration

Clinical trials that provided the data for post hoc analyses are NCT05049460 and NCT05295953.

Effect of Neonatal Abstinence Syndrome Treatment Status and Maternal Depressive Symptomatology on Maternal Reports of Infant Behaviors

OBJECTIVE

The objective of this study is to investigate the effects of maternal perinatal depression symptoms and infant treatment status for neonatal abstinence syndrome (NAS) on maternal perceptions of infant regulatory behavior at 6 weeks of age.

METHODS

Mothers and their infants (N = 106; 53 dyads) were recruited from a rural, White cohort in Northeast Maine. Mothers in medication-assisted treatment (methadone) and their infants (n = 35 dyads) were divided based on the infant's NAS pharmacological treatment (n = 20, NAS+ group; n = 15, NAS- group) and compared with a demographically similar, nonexposed comparison group (n = 18 dyads; COMP group). At 6 weeks postpartum, mothers reported their depression symptoms Beck Depression Inventory-2nd Edition) and infant regulatory behaviors [Mother and Baby Scales (MABS)]. Infant neurobehavior was assessed during the same visit using the Neonatal Network Neurobehavioral Scale (NNNS).

RESULTS

Mothers in the NAS+ group showed significantly higher depression scores than the COMP group (p < .05) while the NAS- group did not. Across the sample, mothers with higher depression scores reported higher infant "unsettled-irregularity" MABS scores, regardless of group status. Agreement between maternal reports of infant regulatory behaviors and observer-assessed NNNS summary scares was poor in both the NAS+ and COMP groups.

CONCLUSIONS

Postpartum women in opioid recovery with infants requiring pharmacological intervention for NAS are more at risk for depression which may adversely influence their perceptions of their infants' regulatory profiles. Unique, targeted attachment interventions may be needed for this population.

The co-use of nicotine and prescription psychostimulants: A review of their behavioral and neuropharmacological interactions

BACKGROUND

Nicotine is commonly co-used with other psychostimulants. These high co-use rates have prompted much research on interactions between nicotine and psychostimulant drugs. These studies range from examination of illicitly used psychostimulants such as cocaine and methamphetamine to prescription psychostimulants used to treat attention deficit hyperactivity disorder (ADHD) such as methylphenidate (Ritalin™) and d-amphetamine (active ingredient of Adderall™). However, previous reviews largely focus on nicotine interactions with illicitly used psychostimulants with sparse mention of prescription psychostimulants. The currently available epidemiological and laboratory research, however, suggests high co-use between nicotine and prescription psychostimulants, and that these drugs interact to modulate use liability of either drug. The present review synthesizes epidemiological and experimental human and pre-clinical research assessing the behavioral and neuropharmacological interactions between nicotine and prescription psychostimulants that may contribute to high nicotine-prescription psychostimulant co-use.

METHODS

We searched databases for literature investigating acute and chronic nicotine and prescription psychostimulant interactions. Inclusion criteria were that participants/subjects had to experience nicotine and a prescription psychostimulant compound at least once in the study, in addition to assessment of their interaction.

RESULTS AND CONCLUSIONS

Nicotine clearly interacts with d-amphetamine and methylphenidate in a variety of behavioral tasks and neurochemical assays assessing co-use liability across preclinical, clinical, and epidemiological research. The currently available research suggests research gaps examining these interactions in women/female rodents, in consideration of ADHD symptoms, and how prescription psychostimulant exposure influences later nicotine-related outcomes. Nicotine has been less widely studied with alternative ADHD pharmacotherapy bupropion, but we also discuss this research.

Cigarette Smoke Modulates Inflammation and Immunity via Reactive Oxygen Species-Regulated Trained Immunity and Trained Tolerance Mechanisms

Significance: Cigarette smoke (CS) is a prominent cause of morbidity and death and poses a serious challenge to the current health care system worldwide. Its multifaceted roles have led to cardiovascular, respiratory, immunological, and neoplastic diseases. Recent Advances: CS influences both innate and adaptive immunity and regulates immune responses by exacerbating pathogenic immunological responses and/or suppressing defense immunity. There is substantial evidence pointing toward a critical role of CS in vascular immunopathology, but a comprehensive and up-to-date review is lacking. Critical Issues: This review aims to synthesize novel conceptual advances on the immunomodulatory action of CS with a focus on the cardiovascular system from the following perspectives: (i) the signaling of danger-associated molecular pattern (DAMP) receptors contributes to CS modulation of inflammation and immunity; (ii) CS reprograms immunometabolism and trained immunity-related metabolic pathways in innate immune cells and T cells, which can be sensed by the cytoplasmic (cytosolic and non-nuclear organelles) reactive oxygen species (ROS) system in vascular cells; (iii) how nuclear ROS drive CS-promoted DNA damage and cell death pathways, thereby amplifying inflammation and immune responses; and (iv) CS induces endothelial cell (EC) dysfunction and vascular inflammation to promote cardiovascular diseases (CVDs). Future Directions: Despite significant progress in understanding the cellular and molecular mechanisms linking CS to immunity, further investigations are warranted to elucidate novel mechanisms responsible for CS-mediated immunopathology of CVDs; in particular, the research in redox regulation of immune functions of ECs and their fate affected by CS is still in its infancy.

Nicotine Enhances Intravenous Self-administration of Cannabinoids in Adult Rats

INTRODUCTION

Nicotine and cannabis are commonly used together, yet few studies have investigated the effects of concurrent administration. Nicotine exhibits reinforcement enhancing effects by promoting the reinforcing properties of stimuli including other drugs. As many studies of this effect used non-contingent nicotine, we implemented a dual-self-administration model where rats have simultaneous access to two drugs and choose which to self-administer throughout a session. Here, we investigated the effect of self-administered or non-contingently delivered nicotine on cannabinoid self-administration.

METHODS

Adult male rats were allowed to self-administer the synthetic cannabinoid WIN 55,212-2 (WIN) intravenously, with or without subcutaneous nicotine injections before each session. A separate group of animals were allowed to self-administer WIN, nicotine, or saline using a dual-catheter procedure, where each solution was infused independently and associated with a separate operant response. A third group of male and female rats were allowed to self-administer delta-9-tetrahydrocannabinol (THC) with or without pre-session injections of nicotine.

RESULTS

Nicotine injections increased self-administration of WIN and THC. During dual self-administration, nicotine availability increased saline and WIN infusions but nicotine intake was not changed by WIN or saline availability. Rats preferred nicotine over saline, but preferred nicotine and WIN equally when both were available. The effect of nicotine on cannabinoid self-administration was acute and reversible when nicotine was no longer present.

CONCLUSIONS

These results expand our understanding of the ability of nicotine to enhance reinforcement of other drugs and suggest that co-use of nicotine and cannabinoids promotes cannabinoid use beyond what would be taken alone.

IMPLICATIONS

This study utilizes a dual intravenous self-administration model to investigate the ability of nicotine to enhance cannabinoid intake. Our results demonstrate that the reinforcement enhancing properties of nicotine on drug use extend to include cannabinoids, but that this effect occurs specifically when nicotine is administered alongside the cannabinoid. Interestingly, cannabinoid use did not promote nicotine intake, suggesting this mechanism of reinforcement is specific to nicotine.

Impact of cannabis legalization in the United States on trends in cannabis use and daily cannabis use among individuals who smoke cigarettes

BACKGROUND

Cannabis legalization and increases in cannabis use are occurring rapidly in the United States (US). Cannabis and tobacco are often used together, but it is unclear whether cannabis legalization will differentially affect cannabis use among those using cigarettes. This study estimated changes from 2004 to 2017 in the prevalence of cannabis use and daily cannabis use by cigarette use status and examined whether state-level cannabis policy modified these trends.

METHODS

Public and restricted-use data from the 2004-2017 National Survey on Drug Use and Health were analyzed. Weighted logistic regressions were used to examine time trends in past-30-day cannabis use and daily caunabis use by cigarette use and cannabis law status from 2004 to 2017.

RESULTS

Cannabis use and daily use increased significantly among those with and without cigarette smoking. Cannabis use and daily cannabis use were consistently 2-10x more common throughout this time among those with, versus without, cigarette smoking. In 2017, cannabis use and daily cannabis use were substantially more common among individuals who use cigarettes, and even greater among those who live in states where cannabis was legal for medical or recreational (i.e., non-medical) use.

CONCLUSIONS

Cannabis use and daily cannabis use are increasing among US individuals who both smoke and do not smoke cigarettes. Cannabis and daily cannabis use are more common among those who smoke cigarettes and elevated even further among those residing in states that have legalized cannabis for recreational (i.e., non-medical) use. Tobacco control efforts should be adjusted to address increases in cannabis use among Americans who smoke cigarettes.

Exploring the Role of DARPP-32 in Addiction: A Review of the Current Limitations of Addiction Treatment Pathways and the Role of DARPP-32 to Improve Them

We are amidst a global addiction crisis, yet stigmas surrounding addiction counterintuitively prevail. Understanding and appreciating the neurobiology of addiction is essential to dissolve this stigma and for the development of new pharmacological agents to improve upon currently narrow therapeutic options. This review highlights this and evaluates dopamine-and-cAMP-regulated phosphoprotein, Mr 32 kDa (DARPP-32) as a potential target to treat various forms of substance abuse. Despite the proven involvement of DARPP-32 in addiction pathophysiology, no robust investigations into compounds that could pharmacologically modulate it have been carried out. Agents capable of altering DARPP-32 signalling in this way could prevent or reverse drug abuse and improve upon currently substandard treatment options.

Global population attributable fraction of potentially modifiable risk factors for mental disorders: a meta-umbrella systematic review

Numerous risk factors for mental disorders have been identified. However, we do not know how many disorders we could prevent and to what extent by modifying these risk factors. This study quantifies the Population Attributable Fraction (PAF) of potentially modifiable risk factors for mental disorders. We conducted a PRISMA 2020-compliant (Protocol: https://osf.io/hk2ag ) meta-umbrella systematic review (Web of Science/PubMed/Cochrane Central Register of Reviews/Ovid/PsycINFO, until 05/12/2021) of umbrella reviews reporting associations between potentially modifiable risk factors and ICD/DSM mental disorders, restricted to highly convincing (class I) and convincing (class II) evidence from prospective cohorts. The primary outcome was the global meta-analytical PAF, complemented by sensitivity analyses across different settings, the meta-analytical Generalised Impact Fraction (GIF), and study quality assessment (AMSTAR). Seven umbrella reviews (including 295 meta-analyses and 547 associations) identified 28 class I-II risk associations (23 risk factors; AMSTAR: 45.0% high-, 35.0% medium-, 20.0% low quality). The largest global PAFs not confounded by indication were 37.84% (95% CI = 26.77-48.40%) for childhood adversities and schizophrenia spectrum disorders, 24.76% (95% CI = 13.98-36.49%) for tobacco smoking and opioid use disorders, 17.88% (95% CI = not available) for job strain and depression, 14.60% (95% CI = 9.46-20.52%) for insufficient physical activity and Alzheimer's disease, 13.40% (95% CI = 7.75-20.15%) for childhood sexual abuse and depressive disorders, 12.37% (95% CI = 5.37-25.34%) for clinical high-risk state for psychosis and any non-organic psychotic disorders, 10.00% (95% CI = 5.62-15.95%) for three metabolic factors and depression, 9.73% (95% CI = 4.50-17.30%) for cannabis use and schizophrenia spectrum disorders, and 9.30% (95% CI = 7.36-11.38%) for maternal pre-pregnancy obesity and ADHD. The GIFs confirmed the preventive capacity for these factors. Addressing several potentially modifiable risk factors, particularly childhood adversities, can reduce the global population-level incidence of mental disorders.

Addiction-Related Outcomes of Nicotine and Alcohol Co-use: New Insights Following the Rise in Vaping

PURPOSE

Nicotine and alcohol-containing products are some of the most commonly used substances of abuse and are both leading causes of preventable death. These substances also have significant interactions that have additive and, in some cases, multiplicative effects on the health consequences of their use. Thus, to reduce these negative consequences, it is important to understand the abuse liability of nicotine and alcohol in combination, especially in the most relevant use cases among those who are most vulnerable. Specifically, as tobacco cigarette use is continually decreasing, vaping is quickly replacing cigarettes as the primary mode of nicotine use. This pattern is especially true in adolescent populations in which vaping has grown considerably. Particularly concerning is that adolescents are more vulnerable than adults to the negative consequences of substance use. It is therefore imperative to revisit the literature as it relates to the rising state of co-use of vaping products with alcohol. Here, we review the clinical outcomes of nicotine and alcohol co-use as they relate to the abuse liability of each individually. Special attention is paid to adolescent findings, where available, as well as investigations that use nontobacco nicotine products as these may more accurately reflect the more recent trends of co-use.

IMPLICATIONS

Though nicotine alone has previously been considered a proxy for tobacco and tobacco cigarette use, combustible routes of administration have been decreasing. They are, instead, being replaced by e-cigarettes that do not involve other tobacco constituents and contain additional nonnicotine constituents of their own. Unfortunately, the literature remains limited with regard to e-cigarettes and their interactions with other substances, especially their prevalent co-use with alcohol. This review attempts to discuss the current literature on nicotine and alcohol co-use in the context of the vaping epidemic, predominantly focusing on addiction-related outcomes and why e-cigarette use may be unique.

Acute nicotine treatment enhances compulsive-like remifentanil self-administration that persists despite contextual punishment

Opioid use disorder (OUD) and opioid-related deaths remain a significant public health crisis having reached epidemic status globally. OUDs are defined as chronic, relapsing conditions often characterized by compulsive drug seeking despite the deleterious consequences of drug taking. The use of nicotine-containing products has been linked to increased likelihood of prescription opioid misuse, and there exists a significant comorbidity between habitual nicotine use and opioid dependence. In rodent models, nicotine administration nearly doubles the amount of opioids taken in intravenous self-administration paradigms. Here, we examined the effect of acute systemic nicotine administration in male rats on responding for the synthetic opioid remifentanil (RMF) in a contextual punishment paradigm using either an exteroceptive punisher (foot-shock) or an interoceptive punisher (histamine). Nicotine administration, relative to saline, increased RMF intake in both unpunished and punished contexts, regardless of form of punishment, and resulted in significantly higher motivation to obtain RMF in the previously punished context, as measured by progressive ratio breakpoint. Additionally, regardless of context, nicotine-treated rats were slower to extinguish RMF responding following drug removal and displayed higher levels of cue-induced reinstatement than saline-treated controls. Furthermore, these data support that, compared with histamine adulteration, contingent foot-shock is a more potent form of punishment, as histamine punishment failed to support contextual discrimination between the unpunished and punished contexts. In contrast to RMF administration, augmentation of responding for an audiovisual cue by nicotine pretreatment was lost following contextual punishment. In conclusion, acute nicotine administration in adult male rats significantly enhances compulsive-like responding for RMF that persists despite contingent punishment of drug-directed responding.

Age- and Sex-Dependent Nicotine Pretreatment Effects on the Enhancement of Methamphetamine Self-Administration in Sprague-Dawley Rats

INTRODUCTION

Initiation of tobacco products typically occurs in adolescence. Adolescence is a critical period in development where the maturation of brain neurocircuitry is vulnerable to nicotine. Nicotine-containing products and psychostimulants, such as methamphetamine (METH), are often co-abused. Rodent studies have shown that nicotine exposure in early adolescence increases subsequent drug intake and reward. Given the exponential increase in e-cigarette use among adolescents, there is a pressing need to understand whether adolescent nicotine exposure impacts concurrent increased methamphetamine use. The objective of this study is to evaluate age, sex, and longitudinal effects of nicotine pretreatment on methamphetamine reinforcement.

METHODS

Male and female Sprague-Dawley rats were pretreated with a sub-chronic, low dose nicotine (2x, 30 μg/kg/0.1 mL, intravenous) or saline during early adolescence (postnatal days 28-31) or adulthood (postnatal days 86-89). Following nicotine pretreatment, on postnatal day 32 or postnatal day 90, animals underwent operant intravenous self-administration for methamphetamine (20 μg/kg/inf) over a 2-hour period for five consecutive days.

RESULTS

Early adolescent nicotine exposure enhances intravenous methamphetamine self-administration in male, but not female adolescents. Male adult rats self-administer methamphetamine over the 5-day testing period, independent of nicotine exposure. In contrast, nicotine exposure increases methamphetamine self-administration in female adults during the later sessions of the 5-day testing period.

CONCLUSIONS

Taken together, our data highlight age- and sex-dependent effects of low dose, sub-chronic nicotine pretreatment on subsequent intravenous methamphetamine self-administration.

IMPLICATIONS

A majority of polysubstance users begin smoking before the age of 18. Mounting evidence highlights adolescent susceptibility to nicotine exposure on brain and behavior. With the escalation in nicotine-containing products and stimulant use among adolescents, it is important to identify the consequences from adolescent nicotine use, including polysubstance use. Our study provides evidence that adolescent nicotine exposure enhances subsequent methamphetamine use, with important sex- and age-dependent effects.

Co-exposure of cocaine and cannabinoids and its association with select biological, behavioural and health outcomes: A systematic scoping review of multi-disciplinary studies

Cocaine use entails severe health- and social-related harms globally. Treatment options for cocaine dependence are highly limited. Benefits of cannabinoids for addiction have been documented, making it opportune to examine existing data on the possible outcomes associated with cannabinoids and cocaine co-use. We conducted a systematic scoping review following the PRISMA guidelines of peer-reviewed, English-language studies published from 2000 to 2021 in four databases (Medline, Web-of-Science, CINAHL Plus, and PsycInfo), assessing the co-exposure of cannabis/cannabinoids with cocaine on behavioural, biological or health outcomes. Both quantitative and qualitative, as well as humans and pre-clinical animals' studies (n=46) were included. Pre-clinical studies (n=19) showed mostly protective effects of cannabidiol (CBD) administration on animal models of addiction (e.g., cocaine-craving, -relapse, and -withdrawal) and cocaine-toxicity. Tetrahydrocannabinol (THC) had more inconsistent results, with both protective and counter-protective effects. Human studies (n=27) were more heterogeneous and assessed natural ongoing cannabis and cocaine use or dependence. Quantitative-based studies showed mostly enhanced harms in several outcomes (e.g., cocaine use, mental health); two available clinical trials found no effect upon CBD administration on cocaine-related treatment outcomes. Qualitative data-based studies reported cannabis use as a substitute for or to alleviate harms of crack-cocaine use. While pre-clinical studies suggest a potential of cannabinoids, especially CBD, to treat cocaine addiction, the few trials conducted in humans found no benefits. Cannabis co-use by cocaine users commonly presents a risk factor, entailing enhanced harms for users. More rigorous, controlled trials are still necessary to investigate cannabinoids' potential considering pre-clinical findings and reported benefits from specific drug users.

Temporal trends in smoking and nicotine dependence in relation to co-occurring substance use in the United States, 2005-2016

BACKGROUND

Despite an overall decline in tobacco use in the United States, secular trends of smoking and nicotine dependence with co-occurring substance use are not well characterized.

METHODS

We examined self-reported tobacco and other substance use in 22,245 participants age 21-59 in the United States from six waves of the National Health and Nutrition Examination Survey (NHANES). Using Joinpoint regression, we assessed secular trends of smoking and nicotine dependence as a function of co-occurring use of alcohol, prescription opioids, marijuana/hashish, cocaine/heroin/methamphetamine, or other injection drug use. Multivariable logistic regressions were fitted to identify the potential risk factors.

RESULTS

During 2005-2016, the prevalence of current smoking decreased (without co-occurring substance use: 17.0 %-12.7 %; with co-occurring use of one substance: 35.3 % to 24.6 %; with co-occurring use of two or more substances: 53.8 %-42.2 %), and moderate-to-severe nicotine dependence decreased as well (8.0 %-4.2 %, 16.0 %-8.8 %, and 23.9 %-15.7 %, respectively). Smoking and nicotine dependence were more likely in those with co-occurring use of one substance (current smoking: odds ratio [OR] = 2.22, 95 % confidence interval [CI] = 2.01-2.45); nicotine dependence: OR = 1.88, 95 % CI = 1.63-2.17) and in those with co-occurring use of two or more substances (current smoking: OR = 5.25, 95 % CI = 4.63-5.95; nicotine dependence: OR = 3.24, 95 % CI = 2.72-3.87).

CONCLUSIONS

Co-occurring substance use was associated with smaller reductions in tobacco use, over time, and with increased odds of nicotine dependence. This suggests that co-occurring substance users should be regarded as a tobacco-related disparity group and prioritized for tobacco control interventions.

Snus and Alcohol: Mutually Rewarding Effects in the Brain? A Matched Controlled Population Study

Background:

The use of moist smokeless tobacco (snus) is increasing in the U.S. and other Western countries, and especially among young people. Snus is associated with several health problems, but the relationship between use of snus and alcohol is scarcely explored. Neuro-cognitive and psychological research suggest an association due to possible mutually rewarding effects in the limbic brain. We investigated this issue in a matched controlled population study.

Methods:

Matched control group design where drinking habits and alcohol consumption in a group of users of snus (n = 1043, mean age = 35.20; n men = 749, n women = 294) were compared to a control group of non-users matched on age and gender (n = 1043, mean age = 35.65; n men = 749, n women = 294). In addition, we registered background variables such as level of education, income, self-perceived general, dental health, mental health, current depressive symptoms, and BMI. In estimation of alcohol consumption, the background variables were used as covariates in factorial analyses of variance (ANCOVA).

Results:

Users of snus had lower level of education, lower income, poorer general, dental, and mental health status than non-users, but there were no differences in BMI. Differences in mental health status were related to drinking habits. Users of snus had a higher frequency of drinking, higher frequency of intoxication, and showed more excess drinking. Controlled for background variables users of snus had a 25.2% higher estimated yearly consumption of alcohol in terms of standard units of alcohol on the weekdays, 26.4% higher on weekends and a 60.2% higher yearly excess consumption.

Conclusion:

Users of snus had an elevated alcohol consumption and another drinking style than non-users. The findings are discussed according to neuro-cognitive and psychopharmacological mechanisms, reward learning and conditioning. The results have implications for prevention, treatment and rehabilitation of alcohol and nicotine dependence.

Tobacco/nicotine and marijuana co-use motives in young adults: Associations with substance use behaviors one year later

Co-administration of tobacco/nicotine and marijuana (e.g., using both products on the same occasion by mixing them in the same delivery device) is a risky, yet common, form of co-use among young adults. Understanding motivations for co-administration co-use, and how these are associated with subsequent use and related problems, is needed to inform policy, prevention, and intervention efforts. We conducted a latent class analysis on 342 young adults with past-year co-administration of tobacco/nicotine and marijuana to determine how emergent classes of 16 co-use motives were associated with use and co-administration co-use of tobacco/nicotine and marijuana one year later. Four classes emerged: (1) a high all class that reported high endorsement of all motives, (2) a high coping class that reported high endorsement of co-use due to coping with stress and bad moods, (3) a high social/physiological reinforcement class that reported low endorsement of coping but high probability of social and relaxation motives and motives to even out effects of each substance, and (4) a low all class that reported low endorsement of all motives. The high all and high coping classes reported greater frequency and quantity of single substance use and co-administration. The high coping class reported more marijuana consequences than the low all class. The high all and high coping classes reported younger age of initiation of each individual substance and co-administration. Considering co-use motives may be useful in identifying those at highest risk for future use and consequences and tailoring interventions to the distinct needs of co-use subgroups. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

A 5-Factor Framework for Assessing Tobacco Use Disorder

Cigarette use is the leading cause of preventable death in the United States. Despite the well documented dangers of smoking, nearly 20% of adults report regular use of tobacco. A majority desire to discontinue but the long-term cessation success rate remains near 4%. One challenge to reducing the prevalence of tobacco use is an incomplete understanding of the individual correlates that reinforce continued use. Evidence from research on nicotine and tobacco suggests that Tobacco Use Disorder is a complex, and multifactorial condition. Personality traits, comorbidities, habits and lifestyle, genetics, socioeconomic status, and mental and physical health all contribute to the risk for dependence and to the likelihood of quitting. This perspective review provides an overview of some common factors that contribute to liability risk for Tobacco Use Disorder and a framework for assessing individual tobacco users. The framework includes 5 areas that research suggests contribute to continued tobacco use: nicotine addiction, psychological influences, behavioral dependencies, neurobiological factors, and social reinforcement. Nicotine addiction includes drug-seeking behavior and the role of withdrawal avoidance. Psychological and emotional states contribute to a perceived reliance on tobacco. Behavioral dependence is reinforced by associative and non-associative learning mechanisms. Neurobiological factors include genetic variables, variations in neurotransmitters and receptors, pharmacogenetics, and interaction between psychiatric illnesses and nicotine use and dependence. Finally, social reinforcement of smoking behavior is explained by a network phenomenon and consistent visual cues to smoke. A comprehensive assessment of individual tobacco users will help better determine appropriate treatment options to achieve improved efficacy and outcomes.

Systemic nicotine enhances opioid self-administration and modulates the formation of opioid-associated memories partly through actions within the insular cortex

Habitual use of nicotine containing products increases propensity to misuse prescription opioids and its prevalence is substantially increased in individuals currently involved in opioid-treatment programs. Nicotine enhances self-administration of many classes of drugs in rodents, though evidence for direct effects on opioids is lacking. We sought to measure the effects of nicotine pretreatment on the reinforcing efficacy of opioids in both self-administration and contextual conditioning paradigms. First, we measured the effect of systemic nicotine pretreatment on self-administration of two opioids. Additionally, we measured the degree to which systemic nicotine pretreatment impacts the formation of morphine-associated contextual memories in conditioned taste avoidance and place preference paradigms. Given the involvement of the insula in the maintenance of substance abuse, its importance in nicotine addiction, and findings that insular inactivation impairs contextual drug conditioning, we examined whether nicotine administered directly to the insula could recapitulate the effects of systemic nicotine. We demonstrate that systemic nicotine pretreatment significantly enhances opioid self-administration and alters contextual conditioning. Furthermore, intra-insula nicotine similarly altered morphine contextual conditioning by blocking the formation of taste avoidance at all three morphine doses tested (5.0, 10, and 20 mg/kg), while shifting the dose–response curve of morphine in the place preference paradigm rightward. In conclusion, these data demonstrate that nicotine facilitates opioid intake and is partly acting within the insular cortex to obfuscate aversive opiate memories while potentiating approach to morphine-associated stimuli at higher doses.

Early adolescent subchronic low-dose nicotine exposure increases subsequent cocaine and fentanyl self-administration in Sprague-Dawley rats

An exponential rise in nicotine-containing electronic-cigarette use has been observed during the period of adolescence. Preclinical studies have shown that nicotine exposure during early adolescence, but not adulthood, increases subsequent drug intake and reward. Although growing clinical trends highlight that stimulant use disorders are associated with the opioid epidemic, very few studies have assessed the effects of adolescent nicotine exposure on opioid intake. The objective of our current study is to develop a new animal model to assess the causal relationship of adolescent nicotine exposure on subsequent opioid intake. In this effort, we first replicate previous studies using a well-established 4-day nicotine paradigm. Rats are pretreated with a low dose of nicotine (2 × , 30 μg/kg/0.1 mL, intravenous) or saline during early adolescence (postnatal days 28-31) or adulthood (postnatal days 86-89). Following nicotine pretreatment on postnatal day 32 or postnatal day 90, animals underwent operant intravenous self-administration for the psychostimulant, cocaine [500 μg/kg/infusion (inf)] or the opioid, fentanyl (2.5 μg/kg/inf). We successfully show that adolescent but not adult, nicotine exposure enhances cocaine self-administration in male rats. Furthermore, we illustrate early adolescent but not adult nicotine exposure enhances fentanyl self-administration, independent of sex. Overall, our findings highlight that adolescence is a unique period of development that is vulnerable to nicotine-induced enhancement for cocaine and fentanyl self-administration in rats.

Targeting the Opioid Receptors: A Promising Therapeutic Avenue for Treatment in “Heavy Drinking Smokers”

Aims

Despite a general decline in tobacco use in the last decades, the prevalence of tobacco smoking in individuals with alcohol use disorder (AUD) remains substantial (45–50%). Importantly, the co-use of both substances potentiates the adverse effects, making it a significant public health problem. Substantial evidence suggests that AUD and Tobacco use disorder (TUD) may share common mechanisms. Targeting these mechanisms may therefore provide more effective therapy. Numerous studies describe a potential role of the endogenous opioid system in both AUD and TUD. Reviewing this literature, we aim to evaluate the efficacy of molecules that target the opioid system as promising therapeutic interventions for treating alcohol and tobacco co-use disorders.

Methods

We provide a synthesis of the current epidemiological knowledge of alcohol and tobacco co-use disorders. We evaluate clinical and preclinical research that focuses on the regulation of the endogenous opioid system in alcohol, nicotine, and their interactions.

Results

The epidemiological data confirm that smoking stimulates heavy drinking and facilitates alcohol craving. Pharmacological findings suggest that treatments that are efficacious in the dual addiction provide a beneficial treatment outcome in comorbid AUD and TUD. In this regard, MOP, DOP and NOP-receptor antagonists show promising results, while the findings prompt caution when considering KOP-receptor antagonists as a treatment option in alcohol and tobacco co-use disorders.

Conclusions

Existing literature suggests a role of the opioid system in sustaining the high comorbidity rates of AUD and TUD. Molecules targeting opioid receptors may therefore represent promising therapeutic interventions in ‘heavy drinking smokers.’

Nicotine and Opioids: a Call for Co-treatment as the Standard of Care

The U.S. is in the midst of an opioid epidemic. At the same time, tobacco use remains the leading cause of preventable death and disability. While the shared biological underpinnings of nicotine and opioid addiction are well established, clinical implications for co-treatment of these two substance use disorders has not been emphasized in the literature, nor have researchers, clinicians, and policy makers adequately outlined pathways for incorporating co-treatment into existing clinical workflows. The current brief review characterizes the metabolic and neural mechanisms which mediate co-use of nicotine and opioids, and then outlines clinical and policy implications for concurrently addressing these two deadly epidemics. Screening, assessment, medication-assisted treatment (MAT), and tobacco-free policy are discussed. The evidence suggests that clinical care and policies that facilitate co-treatment are an expedient means of delivering healthcare to individuals that result in better health for the population while also meeting patients' substance abuse disorder recovery goals.

Effects of chronic treatment with bupropion on self-administration of nicotine + cocaine mixtures in nonhuman primates

Chronic health problems associated with long-term nicotine use are the leading cause of preventable death in the United States. The use of tobacco products is 3-4 times greater among individuals with cocaine use disorder than that observed in the general population. This may reflect the propensity of nicotine to augment the reinforcing effects of cocaine. However, the mechanism of action of nicotine differs from that of cocaine, which presents a significant challenge for the development of pharmacotherapeutic interventions for the management of nicotine + cocaine polydrug abuse. Bupropion, an FDA-approved smoking cessation aid, has pharmacological actions at both monoamine transporters and nicotinic receptors, suggesting that it may be effective at decreasing nicotine + cocaine coabuse. Here, rhesus monkeys (n = 4) responded for food pellets and, separately, intravenous injections of nicotine, cocaine, or nicotine + cocaine mixtures under a second-order FR2(VR16:S) schedule of reinforcement during 7- to 10-day continuous treatment with saline or bupropion (1.0 and 1.8 mg/kg/hr). Results show that bupropion treatment dose-dependently decreased self-administration of nicotine combined with a low dose of cocaine (0.0032 mg/kg/inj); however, when the dose of cocaine in the mixture was higher (i.e., 0.01 mg/kg/inj), bupropion attenuated self-administration in only a subset of subjects. The effective dosage of bupropion increased responding for cocaine alone, nicotine alone, and for saline injections and significantly increased measures of daily activity. The apparent stimulant-like effects of bupropion at the dosage required to decrease cocaine + nicotine self-administration does not support its clinical use for the management of nicotine + cocaine polydrug abuse. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Common and separable neural alterations in substance use disorders: A coordinate-based meta-analyses of functional neuroimaging studies in humans

Delineating common and separable neural alterations in substance use disorders (SUD) is imperative to understand the neurobiological basis of the addictive process and to inform substance‐specific treatment strategies. Given numerous functional MRI (fMRI) studies in different SUDs, a meta‐analysis could provide an opportunity to determine robust shared and substance‐specific alterations. The present study employed a coordinate‐based meta‐analysis covering fMRI studies in individuals with addictive cocaine, cannabis, alcohol, and nicotine use. The primary meta‐analysis demonstrated common alterations in primary dorsal striatal, and frontal circuits engaged in reward/salience processing, habit formation, and executive control across different substances and task‐paradigms. Subsequent sub‐analyses revealed substance‐specific alterations in frontal and limbic regions, with marked frontal and insula‐thalamic alterations in alcohol and nicotine use disorders respectively. Examining task‐specific alterations across substances revealed pronounced frontal alterations during cognitive processes yet stronger striatal alterations during reward‐related processes. Finally, an exploratory meta‐analysis revealed that neurofunctional alterations in striatal and frontal reward processing regions can already be determined with a high probability in studies with subjects with comparably short durations of use. Together the findings emphasize the role of dysregulations in frontostriatal circuits and dissociable contributions of these systems in the domains of reward‐related and cognitive processes which may contribute to substance‐specific behavioral alterations.

Reduced cigarette smoking during injectable extended-release naltrexone treatment for opioid use disorder

BACKGROUND

The prevalence of tobacco cigarette smoking in the US has declined to approximately 15%, yet, it remains over 90% among individuals with opioid use disorder regardless of whether they are currently using opioids illicitly or as opioid substitution therapy. This disparity raises the question of whether opioids facilitate smoking among individuals with opioid use disorder and whether opioid antagonists may reduce it.

OBJECTIVES

Determine whether injectable extended-release naltrexone (XR-NTX) treatment of opioid use disorder patients is associated with a spontaneous smoking reduction. We hypothesized that treatment with XR-NTX for would lead to a reduction in smoking in tobacco cigarette smokers with opioid use disorder.

METHODS

We analyzed data from 64 tobacco cigarette smokers (38% female) with opioid use disorder who were induced on XR-NTX for prevention of relapse to opioids. The number of cigarettes smoked per day and opioid-related craving and withdrawal were assessed at baseline and during treatment.

RESULTS

Smoking was reduced from 14.4 ± 1.0 to 9.8 ± 1.0(p < 0.001) cigarettes per day after one month and 8.6 ± 1.1 cigarettes per day after two months of treatment. Daily cigarette consumption was positively correlated with the pre-treatment frequency of opioid use and opioid-related craving during the XR-NTX treatment.

CONCLUSIONS

XR-NTX treatment in smokers with opioid use disorder was associated with a 29% decline in daily cigarette consumption. Together with prior evidence of increased smoking during opioid agonist therapy, our finding suggests a pharmacodynamic interaction between nicotine and opioid systems that could influence treatment choices in this population. Our findings merit confirmation in a prospective controlled study. (NCT02324725 and NCT01587196).

Increased alcohol preference and intake in nicotine-preferring rats

BACKGROUND

Alcohol and tobacco are among the leading substances that are misused together and shared genetic vulnerability is likely. Increased susceptibility to nicotine self-administration has been shown in alcohol-preferring rat-lines. However, a nicotine-preferring (nP) rat-line has not been studied for alcohol preference.

OBJECTIVES

To evaluate alcohol preference and intake in male and female nP rats. We hypothesized that nP rats and females would drink more ethanol than control rats and males, respectively.

METHODS

nP rats are being selectively outbred for high oral nicotine intake at Ege University. Seventeen nP (18^th generation) and 20 naïve female and male SD rats, not previously exposed to alcohol or nicotine, were used. Twelve-week-old rats were given intermittent access to 20% ethanol in a 2-bottle-choice-procedure for six weeks. After one week withdrawal, six weeks of oral nicotine self-administration was applied.

RESULTS

nP rats drank significantly more ethanol than controls and their preference for ethanol over water was higher. Female rats' ethanol intake was higher than males'. The nP rats' nicotine preference and intake were higher than controls, and they gained less weight.

CONCLUSION

We have shown for the first time that nP rats also have high alcohol intake. Our results support the hypothesis that shared genetic factors may underlie concurrent addiction to nicotine and alcohol and have translational value in understanding their misuse. Considering the increased vulnerability for alcohol use disorder in smokers and sex differences observed, early preventive measures in families with a history of tobacco addiction, specifically targeting female members, could have public health benefits.

Risky decision-making in individuals with substance use disorder: A meta-analysis and meta-regression review

BACKGROUND

This review aims to identify whether risky decision-making is increased in substance users, and the impact of substance type, polysubstance use status, abstinence period, and treatment status on risky decision-making.

METHODS

A literature search with no date restrictions was conducted to identify case-control studies or cross-sectional studies that used behavioral tasks to measure risky decision-making in substance users. A random-effects model was performed. GRADE criteria was used to assess the quality of evidence.

RESULTS

52 studies were enrolled. The result showed that the difference in risky decision-making performance between user groups and control groups was significant (SMD = - 0.590; 95%CI = - 0.849 to - 0.330; p < 0.001; I² = 93.4%; P_{heterogeneity} < 0.001). Subgroup analysis showed that users in the subgroups of alcohol (p < 0.001), tobacco (p < 0.01), cocaine (p < 0.001), opioid (p < 0.001), mixed group (p < 0.01), adult users (p < 0.001), small sample size (p < 0.001), large sample size (p < 0.01), low education (p < 0.001), high education (p < 0.001), short-abstinence period (p < 0.001), long-abstinence period (p < 0.001), without current polysubstance dependence (p < 0.001), and with treatment (p < 0.001) had increased risky decision-making when compared to the controls. On the other hand, elderly substance users with short-abstinence period showed increased risky decision-making. Moreover, current treatment status and polysubstance use may not influence the level of decision-making in substance users.

CONCLUSIONS

The results show that substance use is associated with impaired risky decision-making, indicating that interventions targeting risky decision-making in substance users should be developed for relapse prevention and rehabilitation.

Neuropeptide and cytokine regulation of pain in the context of substance use disorders

Substance use disorders (SUDs) are frequently accompanied by affective symptoms that promote negative reinforcement mechanisms contributing to SUD maintenance or progression. Despite their widespread use as analgesics, chronic or excessive exposure to alcohol, opioids, and nicotine produces heightened nociceptive sensitivity, termed hyperalgesia. This review focuses on the contributions of neuropeptide (CRF, melanocortin, opioid peptide) and cytokine (IL-1β, TNF-α, chemokine) systems in the development and maintenance of substance-induced hyperalgesia. Few effective therapies exist for either chronic pain or SUD, and the common interaction of these disease states likely complicates their effective treatment. Here we highlight promising new discoveries as well as identify gaps in research that could lead to more effective and even simultaneous treatment of SUDs and co-morbid hyperalgesia symptoms.

Nicotine dependence in adolescence predicts later drug criminality: a register-based follow-up of adolescent psychiatric inpatients

Cigarette smoking is common among adolescent psychiatric patients and often precedes the initiation of substance and illicit drug use. This study investigates the association of nicotine dependence (ND), assessed already in adolescence, to subsequent drug crime offenses committed up to young adulthood. The special focus was to examine the dose-response between adolescent ND and later drug-crime offenses. The initial data consist of former adolescent psychiatric inpatients treated in psychiatric inpatient care between the ages 13-17 years. Adolescent DSM-IV based psychiatric disorders were based on the semi-structural diagnostic K-SADS-PL interview. ND in adolescence was measured using the modified Fagerström Tolerance Questionnaire for children and adolescents. Follow-up data on crimes of the study subjects from 15 years of age to early adulthood was obtained from the nationwide Legal Register Center of Finland. A total of 60 (11.8%) drug crime offenders were identified from the initial study population. The likelihood for drug crime offending was statistically significantly increased among those with moderate to severe ND already in adolescence. The higher level of adolescent ND indicated greater number of drug offenses. The common characteristics of drug crime offenders were male gender, out-of-home placement background, exposure to parental divorce and a diagnosis for affective, conduct and substance-use disorder in adolescence. Our study finding, that higher level of ND in adolescence predicts greater number of drug crime offenses up to young adulthood, warrants identification of adolescent smokers at-risk of later drug-related crimes.

The Incentives to Quit tobacco in Pregnancy (IQuiP) protocol: piloting a financial incentive-based smoking treatment for women attending substance use in pregnancy antenatal services

INTRODUCTION

While tobacco smoking prevalence is falling in many western societies, it remains elevated among high-priority cohorts. Rates up to 95% have been reported in women whose pregnancy is complicated by other substance use. In this group, the potential for poor pregnancy outcomes and adverse physical and neurobiological fetal development are elevated by tobacco smoking. Unfortunately, few targeted and effective tobacco dependence treatments exist to assist cessation in this population. The study will trial an evidence-based, multicomponent tobacco smoking treatment tailored to pregnant women who use other substances. The intervention comprises financial incentives for biochemically verified abstinence, psychotherapy delivered by drug and alcohol counsellors, and nicotine replacement therapy. It will be piloted at three government-based, primary healthcare facilities in New South Wales (NSW) and Victoria, Australia. The study will assess the feasibility and acceptability of the treatment when integrated into routine antenatal care offered by substance use in pregnancy antenatal services.

METHODS AND ANALYSIS

The study will use a single-arm design with pre-post comparisons. One hundred clients will be recruited from antenatal clinics with a substance use in pregnancy service. Women must be <33 weeks' gestation, ≥16 years old and a current tobacco smoker. The primary outcomes are feasibility, assessed by recruitment and retention and the acceptability of addressing smoking among this population. Secondary outcomes include changes in smoking behaviours, the comparison of adverse maternal outcomes and neonatal characteristics to those of a historical control group, and a cost-consequence analysis of the intervention implementation.

ETHICS AND DISSEMINATION

Protocol approval was granted by Hunter New England Human Research Ethics Committee (Reference 17/04/12/4.05), with additional ethical approval sought from the Aboriginal Health and Medical Research Council of NSW (Reference 1249/17). Findings will be disseminated via academic conferences, peer-reviewed publications and social media.

TRIAL REGISTRATION NUMBER

Australia New Zealand Clinical Trial Registry (Ref: ACTRN12618000576224).

Early evidence of the impact of cannabis legalization on cannabis use, cannabis use disorder, and the use of other substances: Findings from state policy evaluations

Background: The past decade has seen unprecedented shifts in the cannabis policy environment, and the public health impacts of these changes will hinge on how they affect patterns of cannabis use and the use and harms associated with other substances.Objectives: To review existing research on how state cannabis policy impacts substance use, emphasizing studies using methods for causal inference and highlighting gaps in our understanding of policy impacts on evolving cannabis markets.Methods: Narrative review of quasi-experimental studies for how medical cannabis laws (MCLs) and recreational cannabis laws (RCLs) affect cannabis use and use disorders, as well as the use of or harms from alcohol, opioids, and tobacco.Results: Research suggests MCLs increase adult but not adolescent cannabis use, and provisions of the laws associated with less regulated supply may increase adult cannabis use disorders. These laws may reduce some opioid-related harms, while their impacts on alcohol and tobacco use remain uncertain. Research on RCLs is just emerging, but findings suggest little impact on the prevalence of adolescent cannabis use, potential increases in college student use, and unknown effects on other substance use.Conclusions: Research on how MCLs influence cannabis use has advanced our understanding of the importance of heterogeneity in policies, populations, and market dynamics, but studies of how MCLs relate to other substance use often ignore these factors. Understanding effects of cannabis laws requires greater attention to differences in short- versus long-term effects of the laws, nuances of policies and patterns of consumption, and careful consideration of appropriate control groups.

Current advances in research in treatment and recovery: Nicotine addiction

The health harms of combusted tobacco use are undeniable. With market and regulatory pressures to reduce the harms of nicotine delivery by combustion, the tobacco product landscape has diversified to include smokeless, heated, and electronic nicotine vaping products. Products of tobacco combustion are the main cause of smoking-induced disease, and nicotine addiction sustains tobacco use. An understanding of the biology and clinical features of nicotine addiction and the conditioning of behavior that occurs via stimuli paired with frequent nicotine dosing, as with a smoked cigarette, is important for informing pharmacologic and behavioral treatment targets. We review current advances in research on nicotine addiction treatment and recovery, with a focus on conventional combustible cigarette use. Our review covers evidence-based methods to treat smoking in adults and policy approaches to prevent nicotine product initiation in youth. In closing, we discuss emerging areas of evidence and consider new directions for advancing the field.

Perceived barriers to quitting cigarettes among hospitalized smokers with substance use disorders: A mixed methods study

AIMS

Smoking cessation may promote long-term recovery in patients with substance use disorders (SUD). Yet smoking rates remain alarmingly high in this population. Using a sequential explanatory mixed methods approach, we examined smoking rates among hospitalized patients with SUD at a large safety-net hospital, and then characterized factors associated with smoking behaviors both quantitatively and qualitatively.

METHOD

We abstracted data from all hospital admissions (7/2016-6/2017) and determined demographics, substance use type, and other characteristics associated with cigarette use among those with SUD. We then conducted semi-structured qualitative interviews with 20 hospitalized SUD smokers. We analyzed transcripts to characterize factors that affect patients' smoking habits, focusing on the constructs of the Health Belief Model.

RESULTS

The prevalence of cigarette smoking among hospitalized smokers with SUD was three times higher than those without SUD. Qualitative analyses showed that patients perceived that smoking cigarettes was a less serious concern than other substances. Some patients feared that quitting cigarettes could negatively impact their recovery and perceived that clinicians do not prioritize treating tobacco dependence. Almost all patients with heroin use disorder described how cigarette use potentiated their heroin high. Many SUD patients are turning to vaping and e-cigarettes to quit smoking.

CONCLUSION

Hospitalized patients with SUD have disproportionately high smoking rates and perceive multiple barriers to quitting cigarettes. When designing and implementing smoking cessation interventions for hospitalized patients with SUD, policymakers should understand and take into account how patients with SUD perceive smoking-related health risks and how that influences their decision to quit smoking.

Young adults report increased pleasure from using e-cigarettes and smoking tobacco cigarettes when drinking alcohol

BACKGROUND

Cigarettes share a high rate of co-use with alcohol, particularly among young adults. Studies have demonstrated greater perceived pleasure from smoking cigarettes when drinking alcohol. However, little is known about co-use of electronic cigarettes (e-cigs) and alcohol. The current study sought to compare extent of use and perceived pleasure from cigarettes and e-cigs when drinking alcohol.

METHODS

Young adult bar patrons in California cities (San Diego, Los Angeles, and San Francisco) were recruited in 2015-16 using randomized time-location sampling. Participants completed cross-sectional surveys in bars, reporting the percent of cigarette smoking/e-cig use that occurred under the influence of alcohol, and reported if pleasure from smoking cigarettes/using e-cigs changed when drinking alcohol. Analyses are limited to participants reporting current (past 30-day) use of cigarettes, e-cigs, and alcohol (N = 269; M age = 24.1; 40.1% female, 36.1% Non-Hispanic White).

RESULTS

Participants reported a greater percentage of cigarette smoking compared to e-cig use under the influence of alcohol (cigarettes M = 63.6%; e-cigs M = 46.7%; p < .001). Participants also reported increased pleasure both from smoking cigarettes (M = 3.9; [compared to midpoint of scale 3 - "no change"] p < .001) and using e-cigs (M = 3.3; p < .001) when drinking alcohol. The increase in pleasure was more pronounced for cigarettes compared to e-cigs (p < .001).

CONCLUSIONS

Drinking alcohol is associated with increases in perceived rewarding effects of both cigarettes and e-cigs and thus may increase their abuse liability. This effect may be stronger for cigarettes, which could be an important barrier to switching completely from smoking cigarettes to using e-cigs, or quitting both entirely.

Nitric oxide blockade in mediodorsal thalamus impaired nicotine/ethanol-induced memory retrieval in rats via inhibition of prefrontal cortical pCREB/CREB signaling pathway

Reciprocal connections between the mediodorsal thalamic nucleus (MD) and the prefrontal cortex (PFC) are important for memory processes. Since the co-abuse of nicotine and ethanol affects memory formation, this study investigated the effect of nitric oxide inhibition in the MD on memory retrieval induced by co-administration of nicotine and ethanol. Subsequently, western blot analysis was used to evaluate how this change would alter the PFC pCREB/CREB signaling pathway. Male Wistar rats were bilaterally cannulated into the MD and the memory retrieval was measured by passive avoidance task. Intraperitoneal (i.p.) administration of ethanol (1 g/kg, i.p) 30 min before the test impaired memory retrieval and caused ethanol-induced amnesia. Subcutaneous (s.c.) administration of nicotine (0.05-0.2 mg/kg, s.c.) prevented ethanol-induced amnesia and improved memory retrieval. Intra-MD microinjection of a nitric oxide synthase (NOS) inhibitor, L-NAME (0.5-1 μg/rat) inhibited the improving effect of nicotine (0.2 mg/kg, s.c.) on ethanol-induced amnesia, while intra-MD microinjection of a precursor of nitric oxide, l-arginine (0.25-1 μg/rat), potentiated such effect. Noteworthy, intra-MD microinjection of the same doses of L-NAME or l-arginine by itself had no effect on memory retrieval. Furthermore, intra-MD microinjection of L-NAME (0.05, 0.1 and 0.3 μg/rat) reversed the l-arginine improving effect on nicotine response. Successful memory retrieval significantly increased the p-CREB/CREB ratio in the PFC tissue. Ethanol-induced amnesia, however, decreased this ratio in the PFC while the co-administration of nicotine and ethanol increased the PFC CREB signaling. Interestingly, the inhibitory effect of L-NAME and the potentiating effect of l-arginine on nicotine response were associated with the decrease and increase of the PFC p-CREB/CREB ratio respectively. It can be concluded that MD-PFC connections are involved in the combined effects of nicotine and ethanol on memory retrieval. The mediodorsal thalamic NO system possibly mediated this interaction via the pCREB/CREB signaling pathways in the PFC.