Tolerance and cross-tolerance to neurocognitive effects of THC and alcohol in heavy cannabis users

Simultaneous Alcohol and Cannabis Use and High-Risk Sexual Behaviors

Background

Alcohol and cannabis use rates are highest in college-aged young adults, and both alcohol and cannabis use are independently related to high-risk sexual behaviors (HRSBs). HRSBs (e.g., sex without protection against sexually transmitted infections) are a prevalent public health problem in college students, with little research examining simultaneous alcohol and cannabis use (i.e., using both alcohol and cannabis at the same time so the effects overlap) and HRSBs.

Method

We examined simultaneous alcohol and cannabis-related HRSB frequency, gender differences in simultaneous alcohol and cannabis-related HRSBs, and differences in HRSBs between simultaneous and non-simultaneous users. Alcohol and cannabis using college students (N = 534; Average Age = 19; 66.9% reported identifying as female) were recruited through a psychology department's human subjects research pool and completed a one-time, online, self-report survey.

Results

One-third of participants engaged in simultaneous alcohol and cannabis use prior to sexual intercourse in the past 3 months. Additionally, over one-third of participants reported heavy drinking (4/5 or more drinks for women/men) simultaneously with cannabis use prior to sexual intercourse in the past 3 months. Simultaneous alcohol and cannabis use was significantly and positively related to sexual intercourse after simultaneous use and after heavy drinking simultaneously with cannabis use. Past year simultaneous alcohol and cannabis users, relative to non-simultaneous users, reported increased incidents of sex without protection against sexually transmitted infections. No gender differences in simultaneous alcohol and cannabis-related HRSBs were found.

Conclusions

Future research should continue examining simultaneous alcohol and cannabis use and HRSBs.

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

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

Evaluating possible 'next day' impairment in insomnia patients administered an oral medicinal cannabis product by night: a pilot randomized controlled trial

Cannabis and its major constituents, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), are being widely used to treat sleep disturbances. However, THC can cause acute cognitive and psychomotor impairment and there are concerns that driving and workplace safety might be compromised the day after evening use. Here, we examined possible 'next day' impairment following evening administration of a typical medicinal cannabis oil in adults with insomnia disorder, compared to matched placebo. This paper describes the secondary outcomes of a larger study investigating the effects of THC/CBD on insomnia disorder. Twenty adults [16 female; mean (SD) age, 46.1 (8.6) y] with physician-diagnosed insomnia who infrequently use cannabis completed two 24 h in-laboratory visits involving acute oral administration of combined 10 mg THC and 200 mg CBD ('THC/CBD') or placebo in a randomised, double-blind, crossover trial design. Outcome measures included 'next day' (≥9 h post-treatment) performance on cognitive and psychomotor function tasks, simulated driving performance, subjective drug effects, and mood. We found no differences in 'next day' performance on 27 out of 28 tests of cognitive and psychomotor function and simulated driving performance relative to placebo. THC/CBD produced a small decrease (-1.4%, p=.016, d=-0.6) in accuracy on the Stroop-Colour Task (easy/congruent) but not the Stroop-Word Task (hard/incongruent). THC/CBD also produced a small increase (+8.6, p=.042, d=0.3) in self-ratings of Sedated at 10 h post-treatment, but with no accompanying changes in subjective ratings of Alert or Sleepy (p's>0.05). In conclusion, we found a lack of notable 'next day' impairment to cognitive and psychomotor function and simulated driving performance following evening use of 10 mg oral THC, in combination with 200 mg CBD, in an insomnia population who infrequently use cannabis.

Complexity of Translating Analytics to Recent Cannabis Use and Impairment

While current analytical methodologies can readily identify cannabis use, definitively establishing recent use within the impairment window has proven to be far more complex, requiring a new approach. Recent studies have shown no direct relationship between impairment and Δ9-tetra-hydrocannabinol (Δ9-THC) concentrations in blood or saliva, making legal "per se" Δ9-THC limits scientifically unjustified. Current methods that focus on Δ9-THC and/or metabolite concentrations in blood, saliva, urine, or exhaled breath can lead to false-positive results for recent use due to the persistence of Δ9-THC well outside of the typical 3-4 h window of potential impairment following cannabis inhalation. There is also the issue of impairment due to other intoxicating substances-just because a subject exhibits signs of impairment and cannabis use is detected does not rule out the involvement of other drugs. Compounding the matter is the increasing popularity of hemp-derived cannabidiol (CBD) products following passage of the 2018 Farm Bill, which legalized industrial hemp in the United States. Many of these products contain varying levels of Δ9-THC, which can lead to false-positive tests for cannabis use. Furthermore, hemp-derived CBD is used to synthesize Δ8-THC, which possesses psychoactive properties similar to Δ9-THC and is surrounded by legal controversy. For accuracy, analytical methods must be able to distinguish the various THC isomers, which have identical masses and exhibit immunological cross-reactivity. A new testing approach has been developed based on exhaled breath and blood sampling that incorporates kinetic changes and the presence of key cannabinoids to detect recent cannabis use within the impairment window without the false-positive results seen with other methods. The complexity of determining recent cannabis use that may lead to impairment demands such a comprehensive method so that irresponsible users can be accurately detected without falsely accusing responsible users who may unjustly suffer harsh, life-changing consequences.

The association between single and dual use of cannabis and alcohol and driving under the influence and riding with an impaired driver in a large sample of Canadian adolescents

OBJECTIVE

Dual use of cannabis and alcohol has increased in adolescents, but limited research has examined how it relates to impaired driving or riding with an impaired driver (IDR) compared to single substance use. This study aimed to examine the odds of alcohol- and/or cannabis-IDR among adolescents based on their use of alcohol and/or cannabis, and whether associations differed by gender and age.

METHODS

Cross-sectional survey data were used from a sample of 69,621 students attending 182 Canadian secondary schools in the 2021/22 school year. Multilevel logistic regression estimated the odds of exclusive alcohol-IDR, exclusive cannabis-IDR, and both alcohol and cannabis IDR (alcohol-cannabis-IDR). Substance use interactions with gender and age were tested.

RESULTS

Overall, 14.7% of participants reported IDR; 7.5% reported exclusive alcohol-IDR, 3.2% reported exclusive cannabis-IDR, 4.0% reported alcohol-cannabis-IDR, and 7.4% were unsure if they had experienced IDR. The prevalence of IDR varied across substance use groups, 8.0% among nonuse, 21.9% among alcohol-only use, 35.9% among cannabis-only use, and 49.6% among dual use groups. Gender diverse, older, and students with lower socioeconomic status exhibited a higher likelihood of reporting alcohol-cannabis-IDR. Dual use was significantly associated with 9.5 times higher odds of alcohol-cannabis-IDR compared to alcohol-only use, and 3.0 times higher odds compared to cannabis-only use. Dual use was also associated with an increased likelihood of either alcohol- or cannabis-IDR.

CONCLUSIONS

This study highlights that all students, regardless of substance use, are at risk of IDR, but students engaged in dual use of alcohol and cannabis face an elevated risk compared to both peers who do not use substances and those who use only a single substance. These findings emphasize the importance of targeted interventions that address the risks associated with IDR.

Effects of acute cannabis inhalation on reaction time, decision-making, and memory using a tablet-based application

BACKGROUND

Acute cannabis use has been demonstrated to slow reaction time and affect decision-making and short-term memory. These effects may have utility in identifying impairment associated with recent use. However, these effects have not been widely investigated among individuals with a pattern of daily use, who may have acquired tolerance. The purpose of this study was to examine the impact of tolerance to cannabis on the acute effects as measured by reaction time, decision-making (gap acceptance), and short-term memory.

METHODS

Participants (ages 25-45) completed a tablet-based (iPad) test battery before and approximately 60 min after smoking cannabis flower. The change in performance from before to after cannabis use was compared across three groups of cannabis users: (1) occasional use (n = 23); (2) daily use (n = 31); or (3) no current use (n = 32). Participants in the occasional and daily use group self-administered ad libitum, by smoking or vaping, self-supplied cannabis flower with a high concentration of total THC (15-30%).

RESULTS

The occasional use group exhibited decrements in reaction time (slowed) and short-term memory (replicated fewer shapes) from before to after cannabis use, as compared to the no-use group. In the gap acceptance task, daily use participants took more time to complete the task post-smoking cannabis as compared to those with no use or occasional use; however, the level of accuracy did not significantly change.

CONCLUSIONS

The findings are consistent with acquired tolerance to certain acute psychomotor effects with daily cannabis use. The finding from the gap acceptance task which showed a decline in speed but not accuracy may indicate a prioritization of accuracy over response time. Cognitive and psychomotor assessments may have utility for identifying impairment associated with recent cannabis use.

Effects of combined exposure to ethanol and delta-9-tetrahydrocannabinol during adolescence on synaptic plasticity in the prefrontal cortex of Long Evans rats

Significant exposure to alcohol or cannabis during adolescence can induce lasting disruptions of neuronal signaling in brain regions that are later to mature, such as the medial prefrontal cortex (mPFC). Considerably less is known about the effects of alcohol and cannabis co-use, despite its common occurrence. Here, we used male and female Long-Evans rats to investigate the effects of early-life exposure to ethanol, delta-9-tetrahydrocannabinol (THC), or their combination on high frequency stimulation (HFS)-induced plasticity in the prelimbic region of the mPFC. Animals were injected daily from postnatal days 30-45 with vehicle or THC (escalating doses, 3-20 mg/kg) and allowed to drink vehicle (0.1% saccharin) or 10% ethanol immediately after each injection. In vitro brain slice electrophysiology was then used to record population responses of layer V neurons following HFS in layer II/III after 3-4 weeks of abstinence. We found that THC exposure reduced body weight gains observed in ad libitum fed rats, and reduced intake of saccharin and ethanol. Compared to controls, there was a significant reduction in HFS-induced long-term depression (LTD) in rats exposed to either drug alone, and an absence of LTD in rats exposed to the drug combination. Bath application of indiplon or AR-A014418, which enhance GABAA receptor function or inhibit glycogen synthase kinase 3β (GSK3β), respectively, suggested the effects of ethanol, THC or their combination were due in part to lasting adaptations in GABA and GSK3β signaling. These results suggest the potential for long-lasting adaptations in mPFC output following co-exposure to alcohol and THC.

Cannabis use may attenuate neurocognitive performance deficits resulting from methamphetamine use disorder

OBJECTIVE

Methamphetamine and cannabis are two widely used, and frequently co-used, substances with possibly opposing effects on the central nervous system. Evidence of neurocognitive deficits related to use is robust for methamphetamine and mixed for cannabis. Findings regarding their combined use are inconclusive. We aimed to compare neurocognitive performance in people with lifetime cannabis or methamphetamine use disorder diagnoses, or both, relative to people without substance use disorders.

METHOD

423 (71.9% male, aged 44.6 ± 14.2 years) participants, stratified by presence or absence of lifetime methamphetamine (M-/M+) and/or cannabis (C-/C+) DSM-IV abuse/dependence, completed a comprehensive neuropsychological, substance use, and psychiatric assessment. Neurocognitive domain T-scores and impairment rates were examined using multiple linear and binomial regression, respectively, controlling for covariates that may impact cognition.

RESULTS

Globally, M+C+ performed worse than M-C- but better than M+C-. M+C+ outperformed M+C- on measures of verbal fluency, information processing speed, learning, memory, and working memory. M-C+ did not display lower performance than M-C- globally or on any domain measures, and M-C+ even performed better than M-C- on measures of learning, memory, and working memory.

CONCLUSIONS

Our findings are consistent with prior work showing that methamphetamine use confers risk for worse neurocognitive outcomes, and that cannabis use does not appear to exacerbate and may even reduce this risk. People with a history of cannabis use disorders performed similarly to our nonsubstance using comparison group and outperformed them in some domains. These findings warrant further investigation as to whether cannabis use may ameliorate methamphetamine neurotoxicity.

Subjective effects of simultaneous alcohol and cannabis versus alcohol-only use: A qualitative analysis

OBJECTIVE

Theoretical models of addictive behavior suggest that subjective effects serve as a mechanism through which substance use disorders develop. However, little is known about the subjective effects of simultaneous alcohol and cannabis use, particularly whether simultaneous use (a) heightens specific subjective effects or (b) is related to unique subjective effects relative to single-substance effects. The present study used formative, qualitative data analysis to examine patterns of responses within open-answer text response data on subjective effects of simultaneous use.

METHOD

College students who simultaneously use alcohol and cannabis (N = 443; 68.2% female) were asked to describe how alcohol effects differ on simultaneous alcohol and cannabis use versus alcohol-only use days.

RESULTS

Conventional content analysis revealed nine concepts related to simultaneous (vs. alcohol-only) use subjective effects including as follows: (a) increased/decreased impairment, (b) low arousal/relaxation, (c) balancing/replacement effects, (d) "cross-faded" effects, (e) little-to-no differences, (f) altered sensation and perception, (g) increased negative affective states, (h) increased appetite, and (i) increased/decreased negative consequences. Increased impairment (N = 191) and increased relaxation (N = 110) were the most often endorsed subjective effects, followed by decreased impairment (N = 55), balancing/replacement effects (N = 50) and cross-faded/enhancement effects (N = 44).

CONCLUSIONS

Subjective effects from simultaneous use largely map onto domains of single-substance alcohol and cannabis effects (e.g., relaxation, sociability, cognitive/behavioral impairment), but also include distinct domains related to simultaneous use (e.g., balancing/replacement effects, altered sensation and perception). Future quantitative research is needed to validate measures of subjective effects from simultaneous use and their relations with use behavior. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

A Semi-Naturalistic, Open-Label Trial Examining the Effect of Prescribed Medical Cannabis on Neurocognitive Performance

BACKGROUND AND OBJECTIVES

Medical cannabis use is increasing in Australia and other jurisdictions, yet little is known about the effects of medical cannabis on cognitive function. Findings from studies of non-medical ('recreational') cannabis may not be applicable to patients using prescribed medical cannabis to manage a health condition.

METHODS

In this semi-naturalistic, open-label trial, patients with various health conditions attended a single laboratory session in which they self-administered a standard dose of prescribed medical cannabis as per instructions on the pharmacy label. We assessed cognitive performance using the Cambridge Neuropsychological Test Automated Battery (CANTAB) and Druid application (app) prior to and following (CANTAB: + 3 h; Druid: + 3 and 5.5 h) medical cannabis self-administration. We also assessed subjective drug effects prior to and following (1, 2 and 4 h) medical cannabis self-administration using a range of 0-10 cm visual analogue scales ('stoned', 'sedated', 'relaxed', 'comfortable', 'anxious' and 'confident'). Data were analyzed using linear fixed-effect models.

RESULTS

Participants (N = 40; 22 females) were prescribed a range of products including orally administered oils (n = 23) and flower for vaporization (n = 17). Participants had a mean (standard deviation [SD]) age of 41.38 (12.66) years and had been using medical cannabis for a mean (SD) of 10.18 (8.73) months. Chronic non-cancer pain was the most common indication for medical cannabis use (n = 20), followed by sleep disorder (n = 18) and anxiety (n = 11). The mean (SD) delta-9-tetrahydrocannabinol (THC)/cannabidiol (CBD) dose administered by participants was 9.61 (8.52) mg/9.15 (10.11) mg among those using an oil, and 37.00 (24.53) mg/0.38 (1.58) mg among those who vaporized flower, respectively. Participants' performance improved over time on the CANTAB Multitasking Test and Rapid Visual Information Processing test (both p-values <0.001). All other changes in cognitive performance measures over time were non-significant (p > 0.05). Vaporization of flower was associated with significantly stronger subjective feelings of 'stoned' and 'sedated' relative to oils (both p < 0.001).

CONCLUSIONS

These findings suggest that prescribed medical cannabis may have minimal acute impact on cognitive function among patients with chronic health conditions, although larger and controlled trials are needed.

Effects of combined exposure to ethanol and delta-9-tetrahydrocannabinol during adolescence on synaptic plasticity in the prefrontal cortex of Long Evans rats

Significant exposure to alcohol or cannabis during adolescence can induce lasting disruptions of neuronal signaling in brain regions that are later to mature, such as the medial prefrontal cortex (mPFC). Considerably less is known about the effects of alcohol and cannabis co-use, despite its common occurrence. Here, we used male and female Long-Evans rats to investigate the effects of early-life exposure to ethanol, delta-9-tetrahydrocannabinol (THC), or their combination on high frequency stimulation (HFS)-induced plasticity in the prelimbic region of the mPFC. Animals were injected daily from postnatal days 30 to 45 with vehicle or THC (escalating doses, 3-20 mg/kg) and allowed to drink vehicle (0.1% saccharin) or 10% ethanol immediately after each injection. In vitro brain slice electrophysiology was then used to record population responses of layer V neurons following HFS in layer II/III after 3-4 weeks of abstinence. We found that THC exposure reduced body weight gains observed in ad libitum fed rats, and reduced intake of saccharin and ethanol. Compared to controls, there was a significant reduction in HFS-induced long-term depression (LTD) in rats exposed to either drug alone, and an absence of LTD in rats exposed to the drug combination. Bath application of indiplon or AR-A014418, which enhance GABAA receptor function or inhibit glycogen synthase kinase 3β (GSK3β), respectively, suggested the effects of ethanol, THC or their combination were due in part to lasting adaptations in GABA and GSK3β signaling. These results suggest the potential for long-lasting adaptations in mPFC output following co-exposure to alcohol and THC.

Meta-analysis of acute alcohol effects on response inhibition

Alcohol intoxication impairs response inhibition; however, discrepant findings have been reported regarding the magnitude and moderators of this effect. This meta-analysis of human laboratory studies aimed to quantify acute effects of alcohol on response inhibition and evaluate moderators of this effect. Eligible studies examined alcohol's effects on response inhibition with the Go/No-Go (GNG) task (n = 1616 participants) or Stop Signal Task (SST) (n = 1310 participants). Results revealed a detrimental effect of acute alcohol on response inhibition overall (g = 0.411, 95 % CI [0.350, 0.471]), with similar effects in studies using GNG (g = 0.431, SE = 0.031) and SST (g = 0.366, SE = 0.063). Effect sizes were larger in studies involving higher breath alcohol concentration levels and under GNG conditions that established a prepotent response set. These findings establish the magnitude, precision, and potential moderators of alcohol's effects on inhibitory control, furthering understanding of a key neurobehavioral mechanism proposed to underlie alcohol-related impulsivity and impaired control over consumption.

Experience with dronabinol consumption facilitated a stimulant effect of alcohol and affected alcohol-related changes in frontal cortical endocannabinoid levels in male rats

Combined use of cannabis and alcohol is common in adolescents. However, the extent to which such polydrug exposure affects the brain and behaviors remains under-investigated in preclinical studies. This study tested the hypothesis that combined exposure of Δ-9-tetrahydrocannabinol (THC), the main psychoactive constituent of cannabis, and alcohol will have additive effects on cognitive impairments and altered endocannabinoid levels in the hippocampus and frontal cortex. Male Long Evans rats were provided with daily access to cookies laced with oil or dronabinol, a synthetic THC, during adolescence. Three days after discontinuation of edible THC, the effect of orally administered 3 g/kg alcohol on Barnes maze performance was assessed. The results showed that experience with edible THC facilitated the occurrence of increased moving speed on the maze induced by repeated alcohol administration. However, contrasting to the hypothesis, the combined THC and alcohol exposure did not lead to additive deficits in learning and memory on the Barnes maze. While little effect on endocannabinoid levels was observed in the hippocampus, acute abstinence from alcohol significantly reduced endocannabinoid levels in the frontal cortex. In particular, reduction of N-oleoyl ethanolamine (OEA) and N-stearoyl ethanolamine (SEA) were robust and had an interactive effect with discontinuation from edible THC. These findings add to the scarce literature on THC and alcohol associated changes in endocannabinoid levels and provide insights to future investigations on the roles of OEA and SEA on physiology and behaviors following THC and alcohol co-exposure during adolescence.

Dynamic relations among simultaneous alcohol and cannabis use, subjective responses, and problem drinking during naturally occurring drinking episodes

BACKGROUND

Simultaneous alcohol and cannabis use (SAM) is associated with riskier drinking. However, little is known regarding mechanisms of risk during drinking episodes. The current study tested whether subjective responses to simultaneous vs. alcohol-only use (i.e., high arousal positive/reward, high arousal negative/aggression, low arousal positive/relaxation, low arousal negative/impairment) were mechanisms through which SAM use was associated with daily drinking.

METHODS

Emerging adults who co-use alcohol and cannabis (N=85) completed 21 days of ecological momentary assessment with drink-contingent reports during drinking episodes. Participants reported on their simultaneous use and current subjective effects during drink reports and past-night total drinks consumed and negative consequences experienced the next morning. Three-level multilevel models (momentary, daily, person level) tested whether SAM use predicted subjective responses, and whether subjective responses mediated associations between SAM use, heavier drinking and negative consequences.

RESULTS

At the momentary and day-level, SAM (vs. alcohol-only) use predicted increased high arousal positive/rewarding, low arousal positive/relaxing, and low arousal negative/impairing subjective effects. SAM use indirectly predicted heavier day-level drinking and further negative consequences through high arousal positive/rewarding response. SAM use also indirectly predicted day-level negative consequences through low arousal negative/impairing response. At the person-level, more frequent SAM use predicted higher person-average high arousal positive/rewarding and low arousal positive/relaxing responses, and high arousal positive/rewarding response mediated relation between SAM frequency and heavier drinking.

CONCLUSIONS

Simultaneous use was associated with reward, relief, and impairment, and reward and impairment were mechanisms of risk between SAM use and riskier drinking. Findings may inform theory and just-in-time interventions seeking to reduce alcohol misuse.

Cannabis use breaks in young adults: The highs and lows of tolerance breaks

BACKGROUND/PURPOSE

Cannabis tolerance breaks, or T-breaks, are believed to benefit persons who use cannabis (PUCs) by decreasing tolerance levels to cannabis. However, no prior research, to our knowledge, has compared the effects of T-breaks and other use breaks on cannabis use patterns and outcomes. The current study examined whether the occurrence of cannabis use breaks (tolerance and other use breaks), or the duration of these breaks, is associated with changes in hazardous cannabis use (CUDIT-R), CUD severity, cannabis use frequency, and withdrawal symptoms over a 6-month follow-up.

METHODS

Young adults, who recreationally use cannabis, (N=170, 55.9% female, Mean age=21 yo) completed baseline and on-time 6-month assessments of hazardous cannabis use (CUDIT-R), CUD severity, cannabis use frequency, and withdrawal symptoms. The occurrence of cannabis use breaks and the duration of these breaks during the intervening period was assessed at 6 months.

RESULTS

Taking a T-break was associated with an increase in hazardous cannabis use and CUD severity at 6 months. When considering cannabis use breaks for other reasons, a longer break was associated with a significant decrease in hazardous cannabis use (CUDIT-R), CUD severity, and cannabis use frequency at 6 months.

CONCLUSION

Findings from our study suggest recreational PUCs who take a T-break may be at greater risk for problematic cannabis use. In addition, taking a longer cannabis use break for other reasons may have beneficial effects on cannabis-related outcomes. The ability to abstain from cannabis for other reasons may be protective while individuals who take T-breaks may be important targets for intervention and prevention.

Collisions and cannabis: Measuring the effect of recreational marijuana legalization on traffic crashes in Washington State

OBJECTIVE

Washington State was among the first states in the US to legalize recreational consumption and retail sales of marijuana. Recreational use of cannabis was legalized December 6, 2012, following the passage of Initiative 502 30 days prior. Roughly 19 months later the first retail cannabis stores opened their doors for public sales ("commercialization"). I measure the impact of cannabis legalization and commercialization on traffic collisions in Washington State.

METHODS

With county-level vehicle crash data from the Washington State Department of Transportation collected monthly, I utilize an interrupted time-series framework with Poisson estimation to compare traffic collisions with recreational retail cannabis sales revenue from 2011 (three years pre-commercialization) through 2017 (three years post-commercialization). First, I measure the shift in collisions brought about by Washington's 2012 cannabis legalization. Then, I compare retail cannabis sales-a measure of commercialization-to traffic collisions based on severity of injury (fatal, severe injury, minor injury, non-injury, and all).

RESULTS

After controlling for confounding factors, evidence suggests that recreational cannabis legalization led to fewer fatal and serious injury collisions. Retail cannabis sales generally correlate with more traffic collisions, particularly for less severe (minor injury) crashes. These findings are robust to the inclusion of additional control variables pertaining to county-level cannabis usage and driving behavior while intoxicated.

CONCLUSIONS

Cannabis legalization led to fewer fatal, serious, and minor injury collisions. Commercialization (cannabis sales) correlated with an increase in less severe crashes. Although cannabis use generally increased in Washington State following legalization/commercialization, survey data suggest that driving behavior while under the influence of cannabis did not change significantly over the post-commercialization period. Future research should focus on measuring the dose-dependent impact of cannabis consumption on traffic collisions. This should include recognition of the importance of cannabis dosing, timing, and route of consumption. Lastly, the dangers of poly-drug driving-particularly cannabis and alcohol-are well established and should be high priority for further research.

Preliminary study of the interactive effects of THC and ethanol on self-reported ability and simulated driving, subjective effects, and cardiovascular responses

RATIONALE

Drug- and alcohol-related motor vehicle accidents are a leading cause of morbidity and mortality worldwide. Compared to alcohol, less is known about the effects of cannabis on driving and even less about their combined effects.

OBJECTIVE

To characterize the combined and separate effects of ethanol and tetrahydrocannabinol (THC) on perceived ability to drive, subjective effects, and simulated driving.

METHODS

In a within-subject (crossover), randomized, placebo-controlled, double-blind, 2 × 2 design, the effects of oral THC (10 mg [dronabinol] or placebo) and low-dose intravenous ethanol (clamped at BAC 0.04% or placebo) on perceived ability to drive, simulated driving (standard deviation of lateral position [SDLP]), subjective effects (e.g., "high"), and physiological effects (e.g., heart rate) were studied in healthy humans (n = 18).

RESULTS

Subjects reported reductions in perceived ability to drive (THC < ethanol < combination) which persisted for ~ 6 h (placebo = ethanol, THC < combination). Ethanol and THC produced synergistic effects on heart rate, significant differences compared to either drug alone on perceived ability to drive and feeling states of intoxication (e.g., high), as well increases in SDLP compared to placebo.

CONCLUSIONS

Perceived ability to drive is reduced under the influence of THC against the backdrop of blood alcohol levels that are below the legal limit. People should be aware that the effects of oral THC on driving may persist for up to six hours from administration. Findings are relevant to the increasingly common practice of combining alcohol and cannabinoids and the effects on driving.

Consuming oral cannabidiol prior to a standard alcohol dose has minimal effect on breath alcohol level and subjective effects of alcohol

RATIONALE

Cannabidiol (CBD) is found in the cannabis plant and has garnered attention as a potential treatment for alcohol use disorder (AUD). CBD reduces alcohol consumption and other markers of alcohol dependence in rodents, but human research on CBD and alcohol is limited. It is unknown whether CBD reduces drinking in humans, and mechanisms through which CBD could impact behavioral AUD phenotypes are unknown.

OBJECTIVES

This study explores effects of oral CBD on breath alcohol level (BrAC), and subjective effects of alcohol in human participants who report heavy drinking.

METHODS

In this placebo-controlled, crossover study, participants consumed 30 mg CBD, 200 mg CBD, or placebo CBD before receiving a standardized alcohol dose. Participants were blind to which CBD dose they received at each session and completed sessions in random order. Thirty-six individuals completed at least one session and were included in analyses.

RESULTS

Differences in outcomes across the three conditions and by sex were explored using multilevel structural equation models. BrAC fell fastest in the placebo condition, followed by 30 mg and 200 mg CBD. Stimulation decreased more slowly in the 200 mg CBD condition than in placebo (b =  - 2.38, BCI [- 4.46, - .03]). Sedation decreased more slowly in the 30 mg CBD condition than in placebo (b =  - 2.41, BCI [- 4.61, - .09]). However, the magnitude of condition differences in BrAC and subjective effects was trivial.

CONCLUSIONS

CBD has minimal influence on BrAC and subjective effects of alcohol. Further research is needed to test whether CBD impacts alcohol consumption in humans, and if so, what mechanism(s) may explain this effect.

Alcohol & cannabinoid co-use: Implications for impaired fetal brain development following gestational exposure

Alcohol and marijuana are two of the most consumed psychoactive substances by pregnant people, and independently, both substances have been associated with lifelong impacts on fetal neurodevelopment. Importantly, individuals of child-bearing age are increasingly engaging in simultaneous alcohol and cannabinoid (SAC) use, which amplifies each drug's pharmacodynamic effects and increases craving for both substances. However, to date, investigations of prenatal polysubstance use are notably limited in both human and non-human populations. In this review paper, we will address what is currently known about combined exposure to these substances, both directly and prenatally, and identify shared prenatal targets from single-exposure paradigms that may highlight susceptible neurobiological mechanisms for future investigation and therapeutic intervention. Finally, we conclude this manuscript by discussing factors that we feel are essential in the consideration and experimental design of future preclinical SAC studies.

Protocol for a mobile laboratory study of co-administration of cannabis concentrates with a standard alcohol dose in humans

Cannabis is commonly used among people who drink alcohol, yet evidence on acute effects of co-use is conflicting. Two important variables that may influence the effects of cannabis and alcohol are cannabinoid content (i.e., the ratio of cannabidiol [CBD] and 9-tetrahydrocannabinol [THC]) as well as the order of use (i.e., cannabis before alcohol vs. alcohol before cannabis). Research is mixed regarding the acute imapct of cannabis on alcohol consumption and intoxication, with some studies suggesting additive effects of alcohol and cannabis, and others demonstrating negligible effects of combining these substances. Further complicating this, high-THC-content cannabis concentrates are increasingly popular on the legal-market, but to our knowledge, no studies have explored concentrate and alcohol co-use. In addition to cannabinoid content, order of use may influence intoxication and other acute effects, but is also understudied. Co-use studies typically administer a fixed dose of alcohol before cannabis, and there is a lack of data on the acute effects of cannabis before alcohol. Thus, there is a need for experimental co-use studies exploring the impact of cannabinoid content (particularly of highly potent cannabis concentrates) and order effects on intoxication. This study uses a federally-compliant mobile laboratory procedure to explore the effects of co-administration of legal-market cannabis concentrates with a moderate alcohol dose (.8g/kg) in a sample of community participants who regularly use alcohol and cannabis. The study will also explore alcohol and cannabis order effects (cannabis before alcohol vs. alcohol before cannabis). Outcomes are objective intoxication (measured using blood cannabinoid level, heart rate, psychomotor performance and breath alcohol level [BrAC]) and subjective intoxication (assessed via self-report measures). Overall, this study may influence harm-reduction recommendations for individuals who drink alcohol and use cannabis.

Delay discounting and neurocognitive performance in young adults with differential patterns of substance use: Findings from the Human Connectome Project

A large proportion of individuals who use psychoactive substances regularly use more than one substance. This pattern of behavior, termed polysubstance use, is associated with greater risks than when consuming only a single substance. The present study examined delay discounting, neurocognitive functioning, and demographic indicators among a large, racially and socioeconomically diverse sample of young adults drawn from the Human Connectome Project who reported either non, mono, or dual use of alcohol, tobacco, and/or cannabis. Univariate and multivariate tests suggested individuals who reported using multiple substances were more likely to be male, experienced higher rates of alcohol use disorder, and, when reporting both alcohol use and cannabis involvement, scored lower on a measure of inhibitory control relative to those who reported mono or dual use of alcohol and/or cigarettes. Individuals who reported currently smoking cigarettes exhibited the steepest discounting irrespective of other substances used; however, we observed additive effects for alcohol use and, to a lesser extent, cannabis involvement. Specifically, steeper discounting occurred when individuals who reported either regular alcohol use or > 100 lifetime instances of cannabis use also reported smoking cigarettes. We discuss several hypotheses for this finding related to the diversity of the sample and substances assessed as well as directions for future programmatic lines of research. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Separate and combined effects of alcohol and cannabis on mood, subjective experience, cognition and psychomotor performance: A randomized trial

Co-use of alcohol and cannabis is associated with increased frequency and intensity of use and related problems. This study examined acute effects of alcohol and cannabis on mood, subjective experience, cognition, and psychomotor performance. Twenty-eight healthy cannabis users aged 19-29 years with recent history of binge drinking completed this within-subjects, double-blind, double-dummy, placebo-controlled, randomized clinical trial. Participants received: placebo alcohol and placebo cannabis (<0.1% THC); alcohol (target breath alcohol content [BrAC] 80 mg/dL) and placebo cannabis; placebo alcohol and active cannabis (12.5% THC); and active alcohol and cannabis over four sessions. Profile of Mood States (POMS), Addiction Research Centre Inventory (ARCI), verbal free recall (VFR), Digit Symbol Substitution Test (DSST), Continuous Performance Test (CPT), and grooved pegboard (GPB) task were administered before and approximately 75 min after drinking alcohol (1 h after smoking cannabis ad libitum). Significant effects of condition were found for the POMS (Tension-Anxiety, Confusion) and ARCI (MBG, LSD, PCAG, Euphoria, Sedation), predominantly with greater increases emerging after cannabis or alcohol-cannabis combined relative to placebo. Significant effects were found for VFR (immediate total and delayed recall, percent retained), DSST (trials attempted, trials correct, reaction time), and GPB (non-dominant hand) predominantly with greater declines in performance after alcohol and alcohol-cannabis combined relative to placebo and/or cannabis. Cannabis appeared to affect mood and subjective experience, with minimal impact on cognitive performance. Alcohol appeared to impair cognitive and psychomotor performance, with minimal impact on mood and subjective experience. Acute effects of alcohol and cannabis combined were additive at most.

Indeterminacy of cannabis impairment and ∆9-tetrahydrocannabinol (∆9-THC) levels in blood and breath

Previous investigators have found no clear relationship between specific blood concentrations of ∆⁹-tetrahydrocannabinol (∆⁹-THC) and impairment, and thus no scientific justification for use of legal “per se” ∆⁹-THC blood concentration limits. Analyzing blood from 30 subjects showed ∆⁹-THC concentrations that exceeded 5 ng/mL in 16 of the 30 subjects following a 12-h period of abstinence in the absence of any impairment. In blood and exhaled breath samples collected from a group of 34 subjects at baseline prior to smoking, increasing breath ∆⁹-THC levels were correlated with increasing blood levels (P < 0.0001) in the absence of impairment, suggesting that single measurements of ∆⁹-THC in breath, as in blood, are not related to impairment. When post-smoking duration of impairment was compared to baseline ∆⁹-THC blood concentrations, subjects with the highest baseline ∆⁹-THC levels tended to have the shortest duration of impairment. It was further shown that subjects with the shortest duration of impairment also had the lowest incidence of horizontal gaze nystagmus at 3 h post-smoking compared to subjects with the longest duration of impairment (P < 0.05). Finally, analysis of breath samples from a group of 44 subjects revealed the presence of transient cannabinoids such as cannabigerol, cannabichromene, and ∆⁹-tetrahydrocannabivarin during the peak impairment window, suggesting that these compounds may be key indicators of recent cannabis use through inhalation. In conclusion, these results provide further evidence that single measurements of ∆⁹-THC in blood, and now in exhaled breath, do not correlate with impairment following inhalation, and that other cannabinoids may be key indicators of recent cannabis inhalation.

Self-Reported Effects of Cannabis on ADHD Symptoms, ADHD Medication Side Effects, and ADHD-Related Executive Dysfunction

OBJECTIVE

People with ADHD are more likely to use cannabis but little is known about the effects of cannabis on ADHD symptoms, ADHD medication side effects, or ADHD-related executive dysfunction.

METHOD

Students (n = 1,738) completed an online survey containing measures of ADHD symptoms, cannabis use, perceived effects of cannabis on ADHD symptoms and medication side effects, as well as executive dysfunction.

RESULTS

Participants with ADHD who have used cannabis reported that cannabis has acute beneficial effects on many symptoms of ADHD (e.g., hyperactivity, impulsivity). Further, they perceived cannabis to improve most of their medication side effects (e.g., irritability, anxiety). Finally, cannabis use frequency was a significant moderator of the associations between symptom severity and executive dysfunction.

CONCLUSION

Results suggest people with ADHD may be using cannabis to self-medicate for many of their symptoms and medication side effects and that more frequent use may mitigate ADHD-related executive dysfunction.

Patterns of Cannabis and Alcohol Co-Use: Substitution Versus Complementary Effects

PURPOSE

The purpose of this review is to discuss the literature regarding the concurrent use (co-use) of alcohol and cannabis and competing hypotheses as to whether cannabis acts as a substitute for (i.e., replacing the effects of alcohol, resulting in decreased use) or a complement to (i.e., used to enhance the effects of alcohol, resulting in increased use) alcohol. The impact of cannabis use on alcohol-related outcomes has received increased attention in the wake of ongoing legalization of cannabis for both medical and recreational purposes. Evidence for both hypotheses exists in the literature across a broad range of data collection methods and samples and is carefully reviewed here. In addition, various mechanisms by which cannabis may act as an alcohol substitute or complement are explored in depth with the goal of better understanding equivocal findings.

SEARCH METHODS

This review includes articles that were identified from a search for studies on alcohol and cannabis co-use, with a specific focus on studies exploring complementary versus substitution aspects of co-use. Search terms were included in Google Scholar, PsycINFO, MEDLINE, and Web of Science. Eligible studies were those that measured alcohol and cannabis co-use in human samples in laboratory, survey, or ecological momentary assessment studies, or that directly referenced substitution or complementary patterns of use.

SEARCH RESULTS

Search results returned 650 articles, with 95 meeting inclusion criteria.

DISCUSSION AND CONCLUSIONS

Results of this review reveal compelling evidence for both substitution and complementary effects, suggesting nuanced yet significant distinctions across different populations examined in these studies. Several mechanisms for the impact of cannabis use on alcohol-related outcomes are identified, including patterns and context of co-use, timing and order of use, cannabinoid formulation, pharmacokinetic interactions, and user characteristics (including diagnostic status), all of which may influence substitution versus complementary effects. This review will inform future research studies examining this topic in both clinical and community samples and aid in the development of treatment and prevention efforts targeting those populations most vulnerable to negative consequences of co-use. Finally, this review highlights the need for additional research in more diverse samples and the use of mixed-methods designs to examine both pharmacological and contextual influences on co-use.

Effects of cannabinoid exposure on short-term memory and medial orbitofrontal cortex function and chemistry in adolescent female rhesus macaques

Aim

There is increasing concern that cannabinoid exposure during adolescence may disturb brain maturation and produce long-term cognitive deficits. However, studies in human subjects have provided limited evidence for such causality. The present study utilized behavioral and neuroimaging endpoints in female non-human primates to examine the effects of acute and chronic exposure during adolescence to the cannabinoid receptor full agonist, AM2389, on cognitive processing and brain function and chemistry.

Materials and methods

Adolescent female rhesus macaques were trained on a titrating-delay matching-to-sample (TDMTS) touchscreen task that assays working memory. TDMTS performance was assessed before and during chronic exposure to AM2389, following antagonist (rimonabant) administration, and after discontinuation of the chronic regimen. Resting-state fMRI connectivity and magnetic resonance spectroscopy data were acquired prior to drug treatment, during chronic exposure, and following its discontinuation. Voxels were placed in the medial orbitofrontal cortex (mOFC), a region involved in memory processing that undergoes maturation during adolescence.

Results

TDMTS performance was dose-dependently disrupted by acute AM2389; however, chronic treatment resulted in tolerance to these effects. TDMTS performance also was disrupted by discontinuation of the chronic regimen but surprisingly, not by rimonabant administration during chronic AM2389 treatment. mOFC N-acetylaspartate/creatine ratio decreased after acute and chronic administration but returned to baseline values following discontinuation of chronic treatment. Finally, intra-network functional connectivity (mOFC) increased during the chronic regimen and returned to baseline values following its discontinuation.

Conclusion

Neural effects of a cannabinergic drug may persist during chronic exposure, notwithstanding the development of tolerance to behavioral effects. However, such effects dissipate upon discontinuation, reflecting the restorative capacity of affected brain processes.

Simultaneous use of marijuana and alcohol: Potential prevention targets among young adults who use alcohol

Simultaneous alcohol and marijuana use (SAM) such that their effects overlap has emerged as a behavior that is riskier than using either substance separately. It has been associated with high-risk binge drinking and driving while intoxicated during young adulthood, and it has been demonstrated to cause greater physical and mental impairment than use of alcohol or marijuana separately. To identify intervention and prevention targets specific to SAM, we examined the relationships between alcohol- and marijuana-specific beliefs and attitudes (risk factors) and self-reported SAM compared to non-simultaneous co-use (CAM) and alcohol use only in the past 30 days in a sample of young adults (n = 1,023, mean age = 23.17; SD = 0.43). Of those who reported drinking alcohol in the past 30 days, 20.7% reported SAM, 12.6% reported CAM, and 66.6% reported using only alcohol. Results from multinomial logistic regression analyses indicated that some marijuana-specific risk factors (e.g., belief that it is not at all wrong for someone their age to use marijuana) differentiated SAM or CAM from alcohol use only, but alcohol-specific risk factors generally did not. However, the perceptions that parents approved of their using marijuana or frequently drinking heavily were associated with a greater likelihood of SAM compared to CAM (OR ranged from 2.25 to 3.53). Findings point to the salience of individuals' attitudes and beliefs around marijuana use and their perception of parental approval of heavy drinking and marijuana use as potential targets for prevention programs targeting risk reduction among young adults.

Alcohol-medication interactions: A systematic review and meta-analysis of placebo-controlled trials

Alcohol and other xenobiotics may limit the therapeutic effects of medications. We aimed at investigating alcohol-medication interactions (AMI) after the exclusion of confounding effects related to other xenobiotics. We performed a systematic review and meta-analysis of controlled studies comparing the effects induced by alcohol versus placebo on pharmacodynamic and/or pharmacokinetic parameters of approved medications. Certainty in the evidence of AMI was assessed when at least 3 independent studies and at least 200 participants were available. We included 107 articles (3097 participants): for diazepam, cannabis, opioids, and methylphenidate, we found significant AMI and enough data to assign the certainty of evidence. Alcohol consumption significantly increases the peak plasma concentration of diazepam (low certainty; almost 290 participants), cannabis (high certainty; almost 650 participants), opioids (low certainty; 560 participants), and methylphenidate (moderate certainty; 290 participants). For most medications, we found some AMI but not enough data to assign them the certainty grades; for some medications, we found no differences between alcohol and placebo in any outcomes evaluated. Our results add further evidence for interactions between alcohol and certain medications after the exclusion of confounding effects related to other xenobiotics. Physicians should advise patients who use these specific medications to avoid alcohol consumption. Further studies with appropriate control groups, enough female participants to investigate sex differences, and elderly population are needed to expand our knowledge in this field. Short phrases suitable for indexing terms.

Individual and poly-substance use and condomless sex among HIV-uninfected adults reporting heterosexual sex in a multi-site cohort

BACKGROUND

We analyzed the association between substance use (SU) and condomless sex (CS) among HIV-negative adults reporting heterosexual sex in the Seek, Test, Treat, and Retain (STTR) consortium. We describe the impact of SU as well as person/partner and context-related factors on CS, identifying combinations of factors that indicate the highest likelihood of CS.

METHODS

We analyzed data from four US-based STTR studies to examine the effect of SU on CS using two SU exposures: 1) recent SU (within 3 months) and 2) SU before/during sex. Behavioral data were collected via 1:1 or self-administered computerized interviews. Adjusted individual-study, multivariable relative risk regression was used to examine the relationship between CS and SU. We also examined interactions with type of sex and partner HIV status. Pooled effect estimates were calculated using traditional fixed-effects meta-analysis. We analyzed data for recent SU (n = 6781; 82% men, median age = 33 years) and SU before/during sex (n = 2915; 69% men, median age = 40 years).

RESULTS

For both exposure classifications, any SU other than cannabis increased the likelihood of CS relative to non-SU (8-16%, p-values< 0.001). In the recent SU group, however, polysubstance use did not increase the likelihood of CS compared to single-substance use. Cannabis use did not increase the likelihood of CS, regardless of frequency of use. Type of sex was associated with CS; those reporting vaginal and anal sex had a higher likelihood of CS compared to vaginal sex only for both exposure classifications (18-21%, p < 0.001). Recent SU increased likelihood of CS among those reporting vaginal sex only (9-10%, p < 0.001); results were similar for those reporting vaginal and anal sex (5-8%, p < 0.01). SU before/during sex increased the likelihood of CS among those reporting vaginal sex only (20%; p < 0.001) and among those reporting vaginal and anal sex (7%; p = 0.002). Single- and poly-SU before/during sex increased the likelihood of CS for those with exclusively HIV-negative partners (7-8%, p ≤ 0.02), and for those reporting HIV-negative and HIV-status unknown partners (9-13%, p ≤ 0.03).

CONCLUSION

Except for cannabis, any SU increased the likelihood of CS. CS was associated with having perceived HIV-negative partners and with having had both anal/vaginal sex.

Simulated driving performance among daily and occasional cannabis users

OBJECTIVE

Daily cannabis users develop tolerance to some drug effects, but the extent to which this diminishes driving impairment is uncertain. This study compared the impact of acute cannabis use on driving performance in occasional and daily cannabis users using a driving simulator.

METHODS

We used a within-subjects design to observe driving performance in adults age 25 to 45 years with different cannabis use histories. Eighty-five participants (43 males, 42 females) were included in the final analysis: 24 occasional users (1 to 2 times per week), 31 daily users and 30 non-users. A car-based driving simulator (MiniSim™, National Advanced Driving Simulator) was used to obtain two measures of driving performance, standard deviation of lateral placement (SDLP) and speed relative to posted speed limit, in simulated urban driving scenarios at baseline and 30 min after a 15 min ad libitum cannabis smoking period. Participants smoked self-supplied cannabis flower product (15% to 30% tetrahydrocannabinol (THC). Blood samples were collected before and after smoking (30 min after the start of smoking). Non-users performed the same driving scenarios before and after an equivalent rest interval. Changes in driving performance were analyzed by repeated measures general linear models.

RESULTS

Mean whole blood THC cannabinoids concentrations post smoking were use THC = 6.4 ± 5.6 ng/ml, THC-COOH = 10.9 ± 8.79 ng/mL for occasional users and THC = 36.4 ± 37.4 ng/mL, THC-COOH = 98.1 ± 90.6 ng/mL for daily users. On a scale of 0 to 100, the mean post-use score of subjective high was similar in occasional users and daily users (52.4 and 47.2, respectively). In covariate-adjusted analysis, occasional users had a significant increase in SDLP in the straight road segment from pre to post compared to non-users; non-users decreased by a mean of 1.1 cm (25.5 cm to 24.4 cm) while occasional users increased by a mean of 1.9 cm (21.7 cm to 23.6 cm; p = 0.02). Daily users also increased adjusted SDLP in straight road segments from baseline to post-use (23.2 cm to 25.0 cm), but the change relative to non-users was not statistically significant (p = 0.08). The standardized mean difference in unadjusted SDLP from baseline to post-use in the straight road segments comparing occasional users to non-users was 0.64 (95% CI 0.09 - 1.19), a statistically significant moderate increase. When occasional users were contrasted with daily users, the baseline to post changes in SDLP were not statistically significant. Daily users exhibited a mean decrease in baseline to post-use adjusted speed in straight road segments of 1.16 mph; a significant change compared to slight speed increases in the non-users and occasional users (p = 0.02 and p = 0.01, respectively).

CONCLUSION

We observed a decrement in driving performance assessed by SDLP after acute cannabis smoking that was statistically significant only in the occasional users in comparison to the nonusers. Direct contrasts between the occasional users and daily users in SDLP were not statistically significant. Daily users drove slower after cannabis use as compared to the occasional use group and non-users. The study results do not conclusively establish that occasional users exhibit more driving impairment than daily users when both smoke cannabis ad libitum.

Effects of cannabis use on alcohol consumption in a sample of treatment-engaged heavy drinkers in Colorado

BACKGROUND AND AIMS

Cannabis is commonly used among people who drink alcohol, but evidence suggests a nuanced relationship between alcohol consumption and cannabis use. In particular, among individuals undergoing alcohol treatment the impact of cannabis on alcohol intake may depend upon cannabis use frequency. We aimed to test the effects of within-day cannabis use on total drinks consumed and likelihood of binge drinking on a given day among all participants and compare these relationships between males and females and between individuals who reported infrequent and frequent cannabis use.

DESIGN

This observational study is a substudy of a larger randomized controlled trial (RCT). Individuals were included from the RCT if they reported any cannabis use and were divided into groups based on cannabis use patterns. Alcohol use was compared within and between groups.

SETTING

Individuals were recruited from 2016 to 2020 from community and university settings in Denver and Boulder, CO, USA.

PARTICIPANTS

Of the 182 individuals enrolled in the RCT, 96 cannabis-using subjects were included in these analyses.

MEASUREMENTS

Subjects completed a time-line follow-back (TLFB) at baseline, 4, 8 (end of treatment) and 20 weeks. Daily data on alcohol and cannabis use from the TLFB at all time-points were analyzed.

FINDINGS

Across the sample (n = 96), individuals drank approximately 29% fewer drinks [95% confidence interval (CI) = 18-39%, P < 0.001] and were 2.06 times (95% CI =1.37-3.08, P < 0.001) less likely to have a binge-drinking episode on days that cannabis was used compared with days that cannabis was not used. These patterns were observed in males, females and the infrequent and frequent cannabis use groups. Findings were inconclusive regarding differences in the association between cannabis use and alcohol outcomes when comparing males and females and when comparing infrequent and frequent cannabis use groups.

CONCLUSIONS

Heavy drinkers engaged in treatment to reduce their alcohol consumption who also use cannabis appear to increase their cannabis use on days when they reduce their alcohol consumption.

Alcohol, marijuana, and nicotine use as predictors of impaired driving and riding with an impaired driver among college students who engage in polysubstance use

OBJECTIVE

While alcohol, marijuana, and nicotine are the most commonly used substances, there is limited research on the between- and within-person associations of their use and driving under the influence (DUI) and riding with an impaired driver (RWID). The current study utilized a burst design to assess how use and co-use of these substances is associated with DUI and RWID.

METHODS

College student drinkers with past-year marijuana and/or nicotine use (N = 367) were assessed on two consecutive weekends for three semesters. Logistic regression compared students who only reported drinking to student drinkers who used marijuana, nicotine, or all three substances on likelihood to DUI and RWID. Multilevel logistic models assessed the associations of varied combinations of substances with the daily likelihood of DUI and RWID.

RESULTS

Compared to students who only used alcohol, students who also reported marijuana use were more likely to DUI (OR = 5.44), and students who reported use of alcohol, nicotine and marijuana more likely to DUI (OR = 10.33) and RWID (OR = 10.22). Compared to occasions when only alcohol was used, DUI was more likely on marijuana only occasions (OR = 9.08), and RWID was more likely on alcohol and marijuana occasions (OR = 3.86). However, confidence intervals were wide for effects.

DISCUSSION

Students reporting use of all 3 substances had higher overall risk of DUI and RWID indicating prevention efforts for DUI and RWID should include all substances. Implications for prevention and intervention strategies at the individual and environmental level are discussed.

"Is medical cannabis safe for my patients?" A practical review of cannabis safety considerations

Medical cannabis use is increasing worldwide. Clinicians are commonly asked by patients to provide guidance on its safety and efficacy. Although there has been an increase in research on the role of medical cannabis for a number of different conditions, we found that there was a paucity of clear safety guidance on its use. We aim to address this issue by answering two pertinent clinician safety questions: 1 Can medical cannabis be safely used in this patient? 2. What strategies can be used to ensure that any harms from medical cannabis are mitigated? To address these questions, we reviewed available evidence and provided expert clinical opinion to summarize the fundamental components for evaluating medical cannabis safety and strategies to reduce risk from its use. Our review resulted in a safety-focused framework for medical cannabis initiation and utilization. We provide clear recommendations for patients being considered for cannabis (e.g. precautions, contraindications and drug interactions). Risk mitigation strategies such as appropriate chemovar (strain) selection, routes of administration, and dosing are reviewed. As with any other pharmacotherapy, we review the key components of monitoring and address potential issues that may arise while using medical cannabis. We propose a structured assessment and monitoring strategy that can be used by clinicians recommending cannabis (CRC) to guide patients through each step of their cannabis journey. This framework can be used to ensure that medical cannabis utilization is associated with the lowest possible risk to the patient.

Does variation in trait schizotypy and frequency of cannabis use influence the acute subjective, cognitive and psychotomimetic effects of delta-9-tetrahydrocannabinol? A mega-analysis

BACKGROUND

While the acute effects of cannabis are relatively benign for most users, some individuals experience significant adverse effects. This study aimed to identify whether variation in schizotypal personality traits and frequency of cannabis use influence the acute effects of delta-9-tetrahydrocannabinol (THC).

METHODS

Individual participant data from four double-blind, randomised, placebo-controlled, acute crossover studies involving 128 cannabis users were combined for a mega-analysis. Using multilevel linear models and moderation analyses, frequency of cannabis use and schizotypal personality traits were investigated as potential moderators of the subjective, cognitive and psychotomimetic effects of acute THC.

RESULTS

There was evidence of a moderating effect where increased frequency of cannabis use was associated with reduced intensity of subjective (changes in alertness and feeling stoned) and psychosis-like effects following THC when compared with placebo. Moderating effects of cannabis use frequency on acute memory impairment were weak. Trait schizotypy did not moderate the acute psychosis-like effects of THC compared with placebo.

CONCLUSIONS

Our results suggest that a pattern of domain-specific tolerance develops to the acute effects of THC. Tolerance to the alertness-reducing effects occurred more readily than tolerance to psychotomimetic effects. Only partial tolerance to feeling stoned was found, and there was weak evidence for tolerance to memory impairment. Trait schizotypy did not moderate THC's effects on psychotomimetic symptoms.

Medicinal cannabis and driving: the intersection of health and road safety policy

BACKGROUND

Recent shifting attitudes towards the medical use of cannabis has seen legal access pathways established in many jurisdictions in North America, Europe and Australasia. However, the positioning of cannabis as a legitimate medical product produces some tensions with other regulatory frameworks. A notable example of this is the so-called 'zero tolerance' drug driving legal frameworks, which criminalise the presence of THC (tetrahydrocannabinol) in a driver's bodily fluids irrespective of impairment. Here we undertake an analysis of this policy issue based on a case study of the introduction of medicinal cannabis in Australia.

METHODS

We examine the regulatory approaches used for managing road safety risks associated with potentially impairing prescription medicines and illicit drugs in Australian jurisdictions, as well as providing an overview of evidence relating to cannabis and road safety risk, unintended impacts of the 'zero-tolerance' approach on patients, and the regulation of medicinal cannabis and driving in comparable jurisdictions.

RESULTS

Road safety risks associated with medicinal cannabis appear similar or lower than numerous other potentially impairing prescription medications. The application of presence-based offences to medicinal cannabis patients appears to derive from the historical status of cannabis as a prohibited drug with no legitimate medical application. This approach is resulting in patient harms including criminal sanctions when not impaired and using the drug as directed by their doctor, or the forfeiting of car use and related mobility. Others who need to drive are excluded from accessing a needed medication and associated therapeutic benefit. 'Medical exemptions' for medicinal cannabis in comparable jurisdictions and other drugs included in presence offences in Australia (e.g. methadone) demonstrate a feasible alternative approach.

CONCLUSION

We conclude that in medical-only access models there is little evidence to justify the differential treatment of medicinal cannabis patients, compared with those taking other prescription medications with potentially impairing effects.

The why behind the high: determinants of neurocognition during acute cannabis exposure

Acute cannabis intoxication may induce neurocognitive impairment and is a possible cause of human error, injury and psychological distress. One of the major concerns raised about increasing cannabis legalization and the therapeutic use of cannabis is that it will increase cannabis-related harm. However, the impairing effect of cannabis during intoxication varies among individuals and may not occur in all users. There is evidence that the neurocognitive response to acute cannabis exposure is driven by changes in the activity of the mesocorticolimbic and salience networks, can be exacerbated or mitigated by biological and pharmacological factors, varies with product formulations and frequency of use and can differ between recreational and therapeutic use. It is argued that these determinants of the cannabis-induced neurocognitive state should be taken into account when defining and evaluating levels of cannabis impairment in the legal arena, when prescribing cannabis in therapeutic settings and when informing society about the safe and responsible use of cannabis.

Steering clear: Traffic violations among emerging adults who engage in habitual or casual cannabis use

While some research has shown that cannabis use can impair driving ability, evidence to the degree and impact of impairment are lacking. This study examined the association between habitual or casual cannabis use and past-year traffic violations among emerging adults (EAs). Data come from the 2012 Canadian Community Health Survey-Mental Health. Respondents (n = 5630) were categorized as: early (15-19 y), middle (20-24 y), and late (25-29 y) EAs. Traffic violations were measured using self-report and cannabis use was measured using the WHO Composite International Diagnostic Interview. The prevalence of traffic violations was higher for males (19.2 %) vs females (9.9 %) and middle (16.2 %) and late (19.4 %) EAs vs early (8.8 %) EAs. The odds of reporting traffic violations were higher for EAs who engaged in habitual [OR = 1.77 (1.17-2.67)] or casual [OR = 1.79 (1.27-2.51)] cannabis use when compared to non-users. Age moderated the association such that higher odds of traffic violations were reported in early EAs who were casual cannabis users and middle EAs who were habitual or casual cannabis users when compared to non-users. Use of other drugs was also a moderator-in the absence vs. presence of other drug use, odds of traffic violations were higher in those who engaged in either habitual or casual use of cannabis. When accounting for the moderating effects of age and drug use, habitual and casual cannabis use resulted in increased odds of a traffic violation. Future research is warranted to explore the robustness of our findings.

Driving-Related Behaviours, Attitudes and Perceptions among Australian Medical Cannabis Users: Results from the CAMS 18-19 Survey

As the use of cannabis for medical purposes becomes increasingly prevalent, driving under the influence of cannabis (DUIC) is emerging as a major public health issue. Understanding current behaviours, attitudes and perceptions around DUIC in medical cannabis users is an important first step in addressing this issue. Here we present the results from the driving-related subsection of the Cannabis as Medicine 2018-2019 Survey (CAMS18) of current Australian medical cannabis users (n = 1388). Of the 806 respondents who reported driving a motor vehicle in the last month, 34.6% said they typically drive within 3 hours of cannabis use, thereby risking DUIC, while more than 50% waited at least 7 hours before driving. A majority of respondents thought that their medical cannabis use did not affect their driving ability, and most denied any specific effects of cannabis on speeding, risk taking, reaction time, attentiveness or lane departures. A substantial majority (70.9%) felt confident in accurately assessing their own driving ability after using medical cannabis. Binary logistic regression showed that frequency of use and confidence to assess driving ability were strongly related to DUIC behaviour (i.e. driving soon after cannabis use). These results suggest a relatively high prevalence of DUIC and low perception of risk among this sample of medical cannabis users. Further research is needed to better understand the acute and chronic effects of medical cannabis use on driving and the relation between perceived and actual driving ability.

Childhood polyvictimization and marijuana use trajectories

Despite public sentiment to the contrary, recreational marijuana use is deleterious to adolescent health and development. Prospective studies of marijuana use trajectories and their predictors are needed to differentiate risk profiles and inform intervention strategies. Using data on 15,960 participants in the National Longitudinal Study of Adolescent to Adult Health, variable-centered approaches were used to examine the impact of childhood polyvictimization on marijuana onset, marijuana use from age 15 to 24 years, and marijuana dependence symptoms. Zero-Inflated Poisson latent class growth analysis (ZIP-LCGA) was used to identify marijuana use subgroups, and their associations with childhood polyvictimization were tested via multinomial logit regression within ZIP-LCGA. Results showed that the overall probability and frequency of marijuana use increased throughout adolescence, peaked in early adulthood, and diminished gradually thereafter. Polyvictimization was associated with earlier onset and greater overall use, frequency of use, and dependence symptoms. ZIP-LCGA uncovered four subgroups, including non-users and three classes of users: adolescence-limited users, escalators, and chronic users. Polyvictimization distinguished non-users from all classes of marijuana users. The findings underscore the lasting developmental implications of significant childhood trauma. Children who experience polyvictimization represent a group that may benefit from selective interventions aimed at preventing early, frequent, chronic, and dependent marijuana use.

Impact of 2 Weeks of Monitored Abstinence on Cognition in Adolescent and Young Adult Cannabis Users

OBJECTIVES

Previous research suggests recovery from cannabis-related deficits in verbal learning and memory functioning after periods of cannabis abstinence in adolescents. Here, we examine how cannabis cessation affects cognitive performance over 2 weeks of monitored abstinence compared to controls in adolescents and young adults.

METHODS

Seventy-four participants (35 cannabis users) aged 16-26 ceased all cannabis, alcohol, and other illicit substance consumption for a 2-week period; abstinence was monitored via weekly urinalysis, breath, and sweat patch testing. Starting at baseline, participants completed weekly abbreviated neuropsychological batteries. Measures included tests of attention, inhibition, verbal working memory, and learning. Repeated measures assessed within and between subject effects for time and group status, while controlling for past year alcohol and nicotine use.

RESULTS

Cannabis users showed increased performance compared to controls on sustained attention tasks after 2 weeks of cannabis use.

CONCLUSIONS

Deficits in attention, but not verbal learning and memory, recovered after 2 weeks of monitored abstinence. This differs from previous literature, suggesting that other cognitive domains may show signs of recovery after periods of cannabis cessation in adolescents and young adults.

The association between legalization of cannabis use and traffic deaths in Uruguay

BACKGROUND AND AIMS

While cannabis use has been found to impair motor vehicle driving, the association between cannabis legalization and motor vehicle fatalities is unclear. In Uruguay in December 2013, cannabis for recreational purposes was legalized. This study assessed the association between implementation of this law and changes in traffic fatality rates.

DESIGN

Interrupted time-series analysis of traffic fatality rates of light motor vehicle drivers and motorcyclists in urban and rural settings. Changes are reported as step and trend effects against modeled trends in the absence of legalization.

SETTING

Uruguay, Montevideo and four rural provinces (Colonia, Florida, Río Negro and San José) from 1 January 2012 to 31 December 2017. Cases and measurement Weekly traffic fatalities of light motor vehicle drivers and motorcyclists per type of vehicle. Data were gathered from the National Road Safety Agency of Uruguay and the Ministry of Transport and Public Works, respectively.

RESULTS

Cannabis legalization was associated with a 52.4% immediate increase [95% confidence interval (CI) = 11.6, 93.3, P = 0.012] in the light motor vehicle driver's fatality rate. However, no significant change in the motorcyclists' fatality rate was observed. In Montevideo the legislation was associated with an absolute increase in its light motor vehicle driver's fatality rate by 0.06 (95% CI = 0.01, 0.11, P = 0.025), but no significant associations were observed in rural settings.

CONCLUSIONS

In Uruguay, the 2013 legislation legalizing recreational cannabis consumption may have been associated with an increase in fatal motor vehicle crashes, particularly in light motor-vehicle drivers and urban settings.

Blunted highs: Pharmacodynamic and behavioral models of cannabis tolerance

Acute exposure to cannabis comes with neurocognitive impairment, leading to increased risk of human error and injury. Evidence however indicates that such acute effects are less prominent in chronic users, suggesting cannabis tolerance. Models of cannabis tolerance stress the importance of neurobiological or behavioral adaptations following repeated cannabis exposure. The pharmacodynamic model relates neuroadaptive changes in the brain to a blunted response to cannabis. Downregulation of CB1 receptors in chronic cannabis users has been associated with a normalization of dopaminergic output from the ventral tegmental area to the mesolimbic circuit, and a reduction of impairment during acute cannabis exposure. Such neuroadaptions are absent in occasional users, who show strong increments of dopamine and glutamate levels in the striatum, a loss of functional connectivity within the mesolimbic circuit and neurocognitive impairments when exposed to cannabis. Evidence for a behavioral model of cannabis tolerance that poses that users can have volitional control to overcome functional impairment during cannabis intoxication is relatively weak, and at best shows limited control over a limited number of behavioral functions. Cannabis tolerance is most likely to occur in users that consume high doses of cannabis continuously, at a high pace, for a prolonged period of time. Knowledge on frequency, dose and duration of cannabis use that is needed to achieve, maintain or lessen tolerance however is very limited, but will be of importance in the context of cannabis therapeutics and in legal settings when evaluating the impact of cannabis exposure on human function.

Does Cannabis Use Predict More Severe Types of Alcohol Consequences? Longitudinal Associations in a 3-Year Study of College Students

BACKGROUND

Prior research shows that negative drinking outcomes among young adults may be exacerbated by cannabis use. However, to date, there have been few longitudinal studies of associations between cannabis use and negative alcohol-related consequences. This study examined longitudinal within-person associations between cannabis use and several domains of negative alcohol consequences among young adults and explored the moderating role of sex.

METHOD

We analyzed data from N = 997 students assessed 4 times per year over the first 3 years of university. At each time point, participants completed measures of past-month cannabis use frequency, typical weekly number of drinks, and 8 domains of negative alcohol consequences. Longitudinal associations were examined in multilevel models.

RESULTS

Within-person changes in frequency of cannabis use were not uniquely associated with changes in total alcohol consequences aggregated across several alcohol consequence domains. However, when examining alcohol consequence domains separately, within-person increases in cannabis use frequency were specifically associated with increases in some (but not all) of the more severe types of alcohol consequences, including risky behaviors, poor self-care, and alcohol dependence symptoms. No support was observed for the moderating role of sex in the longitudinal within-person associations between cannabis use and alcohol consequence domains.

CONCLUSIONS

Findings suggest that within-person changes in cannabis use frequency among young adults are associated with corresponding changes in some domains of alcohol consequences (but not others) when examined over the course of several years. Results may inform targeted harm reduction interventions for young adult drinkers who use cannabis, although future research is needed to clarify the mechanisms of the observed associations.

The relationship of cannabis decriminalization in Colorado and cannabis use in individuals with alcohol use disorders

OBJECTIVE

Over the past decade, cannabis use has become increasingly popular in states that include Colorado. During this time, alcohol use disorders (AUDs) and alcohol-related medical conditions have also been consistently recognized as public health problems with increasing prevalence in the state. Despite the widespread use of cannabis in Colorado, the epidemiology of cannabis use among those with AUDs has been poorly described. Therefore, we sought to examine cannabis use among individuals with likely AUDs and individuals with low-risk alcohol use during a time of major Colorado legislative changes before and after legalization of recreational cannabis in 2012.

METHODS

This study was a secondary data analysis conducted with information from 303 participants (80% male) in the Denver, CO metropolitan enrolled between August 2007 and April 2016 for studies related to alcohol and lung health. Of these participants, 188 (62%) were completing inpatient alcohol detoxification with likely AUDs. All participants completed the Alcohol Use Disorder Identification Test (AUDIT) to establish their likelihood of an AUD, and all had information on current cannabis use assessed by questionnaire and urine toxicology testing.

RESULTS

Individuals with likely AUDs more commonly used cannabis compared to control participants (42% vs 27%, p = 0.007). In multiple logistic regression analyses, participant type (likely AUD versus control), tobacco smoking, and age were significantly associated with cannabis smoking; however, the year of participant enrollment was not. Adjusted odds for cannabis use among participants with likely AUDs were 2.97 (1.51-5.82), p = 0.002, while odds for cannabis use among tobacco smokers were 3.67 (1.94-6.93), p < 0.0001. Among control participants, tobacco smoking increased odds of cannabis use seven-fold.

CONCLUSIONS

Our findings highlight the exceptionally high odds of cannabis use among individuals with likely AUDs undergoing alcohol detoxification at a Colorado treatment facility before and after legalization of recreational cannabis. Targeted investigations into the medical and psychiatric consequences of combined alcohol and cannabis use are urgently needed to define its health impact in these vulnerable individuals.

A phase 1, randomized, pharmacokinetic trial of the effect of different meal compositions, whole milk, and alcohol on cannabidiol exposure and safety in healthy subjects

OBJECTIVE

The pharmacokinetics (PK) and safety of single oral 750-mg doses of a plant-derived pharmaceutical formulation of highly purified cannabidiol (CBD; Epidiolex in the USA and Epidyolex in Europe; 100-mg/mL oral solution) were assessed in healthy adults following a high-fat/calorie meal (n = 15), a low-fat/calorie meal (n = 14), whole milk (n = 15), or alcohol (n = 14), relative to the fasted state (n = 29).

METHODS

Blood samples were collected until 96 hours postdose in each period and evaluated by liquid chromatography and tandem mass spectrometry. PK parameters (maximum observed plasma concentration [C_max ], area under the plasma concentration-time curve from time zero to the last observed quantifiable concentration, area under the concentration-time curve from time zero to infinity [AUC_0-∞ ], and time to maximum plasma concentration [t_max ]) of CBD and its major metabolites were derived using noncompartmental analysis.

RESULTS

CBD exposure increased by 3.8-fold for AUC_0-∞ and 5.2-fold for C_max when CBD was administered with a high-fat/calorie meal versus fasted. To a lesser extent, a low-fat/calorie meal enhanced CBD exposure versus fasted with a 2.7-fold increase in AUC_0-∞ and a 3.8-fold increase in C_max . Similarly, when dosed with whole milk, CBD exposure increased versus fasted by 2.4-fold for AUC_0-∞ and 3.1-fold for C_max . Modest elevations in CBD exposure occurred when it was dosed with alcohol: 1.6-fold for AUC_0-∞ and 1.9-fold for C_max . No clinically relevant effect of any test condition on CBD t_max or t_½ versus the fasted state was apparent. The same trend was seen for the CBD metabolites, except that 7-carboxy-cannabidiol t_max was considerably longer when CBD was administered with alcohol (14 vs 4 hours fasted). Inter- and intrasubject variability in PK parameters was moderate to high during the trial.

SIGNIFICANCE

CBD and metabolite exposures were most affected by a high-fat/calorie meal. CBD exposures also increased with a low-fat/calorie meal, whole milk, or alcohol, but to a lesser extent. CBD was tolerated, and there were no severe or serious adverse events during the trial.

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.

Cannabinoids and the Microbiota-Gut-Brain Axis: Emerging Effects of Cannabidiol and Potential Applications to Alcohol Use Disorders

The endocannabinoid system (ECS) has emerged in recent years as a potential treatment target for alcohol use disorders (AUD). In particular, the nonpsychoactive cannabinoid cannabidiol (CBD) has shown preclinical promise in ameliorating numerous clinical symptoms of AUD. There are several proposed mechanism(s) through which cannabinoids (and CBD in particular) may confer beneficial effects in the context of AUD. First, CBD may directly impact specific brain mechanisms underlying AUD to influence alcohol consumption and the clinical features of AUD. Second, CBD may influence AUD symptoms through its actions across the digestive, immune, and central nervous systems, collectively known as the microbiota-gut-brain axis (MGBA). Notably, emerging work suggests that alcohol and cannabinoids exert opposing effects on the MGBA. Alcohol is linked to immune dysfunction (e.g., chronic systemic inflammation in the brain and periphery) as well as disturbances in gut microbial species (microbiota) and increased intestinal permeability. These MGBA disruptions have been associated with AUD symptoms such as craving and impaired cognitive control. Conversely, existing preclinical data suggest that cannabinoids may confer beneficial effects on the gastrointestinal and immune system, such as reducing intestinal permeability, regulating gut bacteria, and reducing inflammation. Thus, cannabinoids may exert AUD harm-reduction effects, at least in part, through their beneficial actions across the MGBA. This review will provide a brief introduction to the ECS and the MGBA, discuss the effects of cannabinoids (particularly CBD) and alcohol in the brain, gut, and immune system (i.e., across the MGBA), and put forth a theoretical framework to inform future research questions.