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

Effects of alcohol and cannabis co-use on salience network resting state functional connectivity in individuals who drink alcohol heavily

INTRODUCTION

The salience network may be linked to addiction. Evidence suggests less salience network resting state functional connectivity (rsFC) from heavy alcohol use, but higher rsFC within and between brain networks from regular cannabis use. Given the rise in alcohol-cannabis co-use, the present study sought to elucidate rsFC between regions within the salience network and regions across the whole brain in individuals who use no drugs regularly, those who use alcohol only heavily, and those who co-use alcohol-cannabis.

METHODS

This is a secondary analysis of three clinical laboratory studies. A total of sixty individuals were classified into one of three groups based on their drug use: control (n = 16), heavy alcohol use only (n = 27), and heavy alcohol and regular cannabis co-use (n = 17). All participants completed resting state fMRI scans. Seed regions from the salience network were used to examine group differences in rsFC.

RESULTS

Main effects of group on rsFC emerged between the anterior cingulate cortex, left and right anterior insula, and left supramarginal gyrus seeds and regions associated with motor, sensory, visual, and executive control functioning (all ps < 0.05). Post-hoc analyses revealed less rsFC between alcohol-only and co-use groups as compared to controls (all ps < 0.05), but no differences between alcohol-only and co-use groups (all ps > 0.05).

CONCLUSIONS

This preliminary study suggests that co-using alcohol-cannabis may not be associated with any additive or contrasting effects on rsFC compared to using alcohol alone. Thus, in individuals who co-use alcohol-cannabis, alcohol may drive neural alterations associated with inhibitory control and substance craving.

Proximal antecedents and acute outcomes of simultaneous alcohol and cannabis use: Systematic review of daily- and event-level studies

Many studies have revealed that individuals who engage in simultaneous use of alcohol and cannabis report elevated substance-related consequences relative to those who use only alcohol or cannabis; however, evidence from emerging studies examining within-person differences across simultaneous use and single substance use occasions is less consistent. This systematic review aimed to synthesize findings from existing day- and event-level studies of within-person differences in the proximal antecedents and acute outcomes associated with simultaneous use versus single substance use episodes. Our search strategy revealed 30 eligible articles. Two categories of antecedents (i.e., internal [e.g., motives] and external [e.g., social context]) and three categories of outcomes (i.e., consumption behavior, general positive and negative consequences, and specific consequences) were identified. The current literature consistently suggests that greater day- or event-level social and enhancement motives, as well as being in a social context, predict greater likelihood of engaging in simultaneous use compared with alcohol- or cannabis-only use. However, there was heterogeneity in findings regarding the role of other person-level antecedents. Further, while most evidence pointed to heavier alcohol consumption on simultaneous use occasions versus alcohol-only occasions, findings for elevations in acute negative and positive substance-related consequences on simultaneous use versus single substance use occasions were mixed. Additionally, four studies found that increased consequences on simultaneous use occasions depended on the level of alcohol consumed. This review identifies several antecedents for simultaneous use events but suggests that simultaneous use occasions are not always associated with more acute harms than single substance use occasions. Given the extent to which the current literature is mixed, this review emphasizes the importance of methodological improvements and future research examining the mechanisms linking simultaneous use with substance-related consequences to help reconcile findings across within-person and between-person studies.

Alcohol and cannabis use in daily lives of college-attending young adults: Does co-use correspond to greater reported pleasure?

Co-use of alcohol and cannabis is prevalent and linked with heightened risk for substance-related harms. The current study investigated the role of substance-related pleasure as a reinforcing factor for co-use relative to alcohol or cannabis use. Specifically, we used data from a 21-day diary study of college students to examine day-level associations between co-use and self-reported substance-related pleasure (any, level of pleasure). Participants were 237 college students (65 % female sex at birth, ages 18-24) who reported 1+ alcohol and cannabis co-use occasion. Participants completed daily surveys across 21 consecutive days about yesterday's substance use and experiences of pleasure, yielding 2,086 daily surveys involving alcohol and/or cannabis use. Multilevel models indicated that odds of substance-related pleasure were higher on days with co-use relative to days with single-substance use, and level of pleasure was higher on co-use days relative to cannabis but not alcohol use days. Pleasure may serve as a reinforcing property of co-use that may be related to continued use despite experience of negative consequences. Intensity of pleasure related to co-use appears to be largely driven by use of alcohol. However, given mixed findings concerning level of pleasure, individuals may report co-use increases feelings of pleasure but do not actually experience more pleasure. Pleasure may serve as a viable target in future prevention and intervention programming targeting co-use.

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.

VC, Niez RA, Delos Santos FE, Magramo MM, Yap-Tan AR, Sy FAR, Kasimieh O. Predictors and Prevalence of Alcohol and Cannabis Co-use Among Filipino Adolescents: Evidence From a School-based Student Health Survey

OBJECTIVES

This study explored the prevalence and predictors of alcohol and cannabis co-use among 9263 Filipino adolescents, using data from the 2019 Global School-based Student Health Survey (GSHS).

METHODS

We conducted a cross-sectional secondary analysis of the GSHS, targeting adolescents aged 13-17 years and excluding cases with incomplete data on alcohol and cannabis use. Our analysis employed the bivariate chi-square test of independence and multivariable logistic regression using Stata version 18 to identify significant predictors of co-use, with a p-value threshold set at 0.05.

RESULTS

The weighted prevalence of co-users was 4.2% (95% confidence interval [CI], 3.4 to 5.3). Significant predictors included male sex (adjusted odds ratio [aOR], 4.50; 95% CI, 3.31 to 6.10; p<0.001) and being in a lower academic year, specifically grade 7 (aOR, 4.08; 95% CI, 2.39 to 6.99; p<0.001) and grade 8 (aOR, 2.20; 95% CI, 1.30 to 3.72; p=0.003). Poor sleep quality was also a significant predictor (aOR, 1.77; 95% CI, 1.29 to 2.44; p<0.001), as was a history of attempted suicide (aOR, 5.31; 95% CI, 4.00 to 7.06; p<0.001). Physical inactivity was associated with lower odds of co-use (aOR, 0.45; 95% CI, 0.33 to 0.62; p<0.001). Additionally, non-attendance of physical education classes (aOR, 1.48; 95% CI, 1.06 to 2.05; p=0.021), infrequent unapproved parental checks (aOR, 1.37; 95% CI, 1.04 to 1.80; p=0.024), and lower parental awareness of free-time activities (aOR, 0.63; 95% CI, 0.45 to 0.87; p=0.005) were associated with higher odds of co-use. Factors not significantly linked to co-use included age group, being in grade 9, always feeling lonely, having no close friends, being bullied outside school, and whether a parent or guardian understood the adolescent's worries.

CONCLUSIONS

The findings highlight the critical need for comprehensive interventions in the Philippines, addressing not only physical inactivity and parental monitoring but also focusing on sex, academic grade, participation in physical education classes, sleep quality, and suicide attempt history, to effectively reduce alcohol and cannabis co-use among adolescents.

Lifetime use of alcohol and cannabis among U.S. adolescents across age: Exploring differential patterns by sex and race/ethnicity using the 2019 NSDUH data

Background

Early use of alcohol and cannabis is associated with health and social problems. It is unclear how lifetime use changes for each additional year of age during adolescence, and whether this change varies by sex and race/ethnicity. This study characterized lifetime rates of alcohol and cannabis use by age among 12- to 17-year-old American youth and explored differential patterns by sex and race/ethnicity.

Methods

Data were obtained from the 2019 National Survey on Drug Use and Health. Analyses were restricted to 12-17-year-olds who were non-Hispanic White, non-Hispanic Black, or Hispanic/Latino (n = 11,830). We estimated the increase in lifetime use of alcohol and cannabis by age for the full sample and stratified by sex and race/ethnicity. Slopes of the regression lines were compared to assess differential patterns across groups.

Results

In these cross-sectional analyses, reported lifetime use increased substantially from age 12 to 17 for alcohol (6.4 % to 53.2 %) and cannabis (1.3 % to 35.9 %). The increase in lifetime alcohol use was slightly, but not significantly, steeper among girls than boys (F1,8 = 3.40, p = 0.09). White and Latino youth showed similar rates of increase in lifetime alcohol use, which was significantly flatter among Black youth (F2,12=21.26, p<0.0001). Latino youth had a slightly, but not significantly, steeper increase in lifetime cannabis use than White and Black youth (F2,12=3.17, p = 0.07).

Conclusions

Reports of lifetime alcohol and cannabis use substantially increase from age 12 to 17 and the rates are different according to sex and race/ethnicity, highlighting the need for early and tailored substance use prevention in adolescents.

Cannabis craving in response to alcohol cues in the laboratory and in daily life among adolescents ages 15-17 years

BACKGROUND

Most adolescents who drink alcohol also use cannabis, and adolescents who use both substances experience worse long-term outcomes than adolescents who use only one or the other. Recent clinical trials with adolescents and emerging adults show that alcohol cues are associated with elevated cannabis craving in the natural environment but not in the laboratory, highlighting cross-cue reactivity as a potential intervention target. This study extends this work to a younger sample of adolescents at an earlier stage of substance use to examine the generalizability of prior findings and inform etiological mechanisms.

METHODS

Participants were 81 adolescents aged 15-17 years who endorsed past-month alcohol and lifetime cannabis use. They completed a laboratory cue reactivity protocol where they rated their cannabis craving during alcohol cue and control conditions. They also completed 24 days of ecological momentary assessment where they reported multiple times per day on their cannabis craving and whether alcohol cues were visible.

RESULTS

Mixed models demonstrated lower cannabis craving following alcohol cue presentation in the laboratory compared to control cues, but higher cannabis craving during moments when alcohol was visible in daily life compared to moments when alcohol was not visible. Frequency of cannabis use at baseline was associated with greater cannabis craving in the laboratory and in daily life regardless of cue type or alcohol visibility, and cannabis craving following alcohol cue presentation in the laboratory was positively related to daily life cannabis craving across contexts.

CONCLUSIONS

This study adds to prior work suggesting that daily life cannabis craving is elevated when alcohol cues are visible. This cross-cue reactivity may be one factor that drives and maintains alcohol and cannabis use in adolescence.

Cumulative Health Vulnerabilities Among Adolescents by Age and Neighborhood Opportunity

BACKGROUND AND OBJECTIVES

Early detection of health vulnerabilities in adolescents is integral to promoting healthy behaviors into adulthood. Our objective was to quantify the prevalence of health vulnerabilities among adolescents and examine differences by age and neighborhood opportunity.

METHODS

In a cross-sectional analysis of electronic health record data for adolescents aged 13 to 18 years with preventive visits in a large pediatric primary care network between September 2021 and September 2022, we examined 5 health vulnerabilities: Tobacco use, substance use, firearm access, condomless intercourse, and depressive symptoms. Health vulnerabilities were assessed via self-reported adolescent health questionnaire and the validated Patient Health Questionnaire-Modified. Prevalence of health vulnerabilities were calculated alone and in combination, and compared by age and by quintile of neighborhood Child Opportunity Index (COI) score. Multivariable logistic regression estimated associations of neighborhood COI with reporting ≥2 health vulnerabilities.

RESULTS

Among 40 197 adolescents (57.7% aged 13-15 years, 66.3% living in "high"/"very high" COI neighborhoods), 29.7% reported at least 1 health vulnerability and 7.9% reported ≥2 vulnerabilities. Cumulative health vulnerabilities were more prevalent among older adolescents and adolescents from lower opportunity neighborhoods. In adjusted models, lower COI was associated with 65% higher odds of having ≥2 vulnerabilities (odds ratio 1.65, 95% confidence interval 1.43-1.91) compared with adolescents from the highest COI quintile.

CONCLUSIONS

Understanding the relationship between health vulnerabilities and neighborhood opportunities among adolescents may allow pediatric primary care providers and health systems to offer more tailored community support services and transdiagnostic specialized care navigation to address the health needs of teens with multiple vulnerabilities.

Consequences of adolescent drug use

Substance use in adolescence is a known risk factor for the development of neuropsychiatric and substance use disorders in adulthood. This is in part due to the fact that critical aspects of brain development occur during adolescence, which can be altered by drug use. Despite concerted efforts to educate youth about the potential negative consequences of substance use, initiation remains common amongst adolescents world-wide. Additionally, though there has been substantial research on the topic, many questions remain about the predictors and the consequences of adolescent drug use. In the following review, we will highlight some of the most recent literature on the neurobiological and behavioral effects of adolescent drug use in rodents, non-human primates, and humans, with a specific focus on alcohol, cannabis, nicotine, and the interactions between these substances. Overall, consumption of these substances during adolescence can produce long-lasting changes across a variety of structures and networks which can have enduring effects on behavior, emotion, and cognition.

Effects of combined use of alcohol and delta-9-tetrahydrocannibinol on working memory in Long Evans rats

The increase in social acceptance and legalization of cannabis over the last several years is likely to increase the prevalence of its co-use with alcohol. In spite of this, the potential for effects unique to co-use of these drugs, especially in moderate doses, has been studied relatively infrequently. We addressed this in the current study using a laboratory rat model of voluntary drug intake. Periadolescent male and female Long-Evans rats were allowed to orally self-administer ethanol, Δ9-tetrahydrocannibinol (THC), both drugs, or their vehicle controls from postnatal day (P) 30 to P47. They were subsequently trained and tested on an instrumental behavior task that assesses attention, working memory and behavioral flexibility. Similar to previous work, consumption of THC reduced both ethanol and saccharin intake in both sexes. Blood samples taken 14 h following the final self-administration session revealed that females had higher levels of the THC metabolite THC-COOH. There were modest effects of THC on our delayed matching to position (DMTP) task, with females exhibiting reduced performance compared to their control group or male, drug using counterparts. However, there were no significant effects of co-use of ethanol or THC on DMTP performance, and drug effects were also not apparent in the reversal learning phase of the task when non-matching to position was required as the correct response. These findings are consistent with other published studies in rodent models showing that use of these drugs in low to moderate doses does not significantly impact memory or behavioral flexibility following a protracted abstinence period.

Childhood adversity and developmental trajectories of alcohol and cannabis co-use

OBJECTIVE

A large body of literature has noted detrimental effects of childhood adversity on young adult behavioral health, yet few studies have assessed how early childhood adversity influences the development of alcohol and cannabis co-use.

METHOD

In the present study we use data from an ongoing longitudinal cohort (N = 2507) to understand how early childhood adversity influences transitions into alcohol and cannabis co-use trajectories. We also explore how sex, depression, and anxiety are associated with transition probabilities. We used latent transition analysis to examine transitions from emergent childhood adversity classes to classes of parallel alcohol and cannabis co-use from ages 17 to 24 years.

RESULTS

Those who reported high levels of childhood adversity were more likely to transition into classes with relatively chronic and rapidly increasing alcohol and cannabis co-use during young adulthood. Young adults who both experienced high levels of childhood adversity and transitioned into increasing alcohol and cannabis co- use trajectories were more likely to be male and meet clinical cutoff for depression.

CONCLUSION

Our results indicate an incrementally more nuanced set of risk profiles, with differential risk of alcohol and cannabis co-use trajectories, dependent on one's experience of childhood adversity.

PUBLIC HEALTH SIGNIFICANCE

Results of the present study note important heterogeneity in alcohol and cannabis co-use throughout young adulthood, with general trends showing increases in co-use. The present study also shows differential risk of alcohol and cannabis co-use dependent on prior experience of childhood adversity.

Cannabis Recreational Legalization and Prevalence of Simultaneous Cannabis and Alcohol Use in the United States

BACKGROUND

Simultaneous cannabis/alcohol use, using both substances within a short time interval so that their effects overlap, has a greater risk of potential negative consequences than single-substance use and is more common in younger age. Relationships between recreational cannabis laws (RCLs) and changes in simultaneous cannabis/alcohol use prevalence remain untested.

OBJECTIVE

To examine trends in simultaneous cannabis/alcohol use from 2008 to 2019, and investigate associations between implementation of RCLs (i.e., presence of active legal dispensaries or legal home cultivation) and simultaneous cannabis/alcohol use in the United States (U.S.).

DESIGN

Repeated cross-sectional samples from the 2008-2019 U.S. National Survey on Drug Use and Health (NSDUH).

PARTICIPANTS

Respondents (51% female) aged 12 and older.

INTERVENTIONS

Changes in simultaneous cannabis/alcohol use before and after RCL implementation (controlling for medical cannabis law implementation) were compared in different age groups (12-20, 21-30, 31-40, 41-50, 51+), using adjusted multi-level logistic regression with state random intercepts and an RCL/age group interaction.

MEASUREMENTS

Self-reported simultaneous cannabis/alcohol use.

RESULTS

From 2008 to 2019, the overall prevalence of simultaneous cannabis/alcohol use declined among those aged 12-20 but increased in adults aged 21+. Model-based simultaneous cannabis/alcohol use prevalence increased after RCL implementation among respondents aged 21-30 years (+1.2%; aOR= 1.15 [95%CI = 1.04-1.27]), 31-40 years (+1.0; 1.15 [1.04-1.27]), and 41-50 years (+1.75; 1.63 [1.34-1.98]), but not in individuals aged <21 or 51+ years.

CONCLUSIONS

Implementation of recreational cannabis policies resulted in increased simultaneous use of cannabis and alcohol, supporting the complementarity hypothesis, but only among adults aged 21+. Efforts to minimize harms related to simultaneous cannabis/alcohol use are critical, especially in states with RCLs. Future studies should investigate cultural norms, perceived harm, and motives related to simultaneous use.

Associations between alcohol and cannabis use order, frequency, quantity, and consequences in a college sample of individuals who co-use alcohol and cannabis

BACKGROUND AND OBJECTIVES

Using both alcohol and cannabis (either at the same time or at different times) is common among college students, and is called "co-use." Using these substances simultaneously, such that their effects overlap, is thought to be an especially risky co-use pattern. Gaining a better understanding of how co-use patterns relate to substance use and consequences could aid prevention and intervention efforts.

METHODS

We examined college students (N = 401) who reported using both alcohol and cannabis at least once in the past 30 days. Path analysis was used to explore relations among co-use patterns (number of days in a typical week that participants used both alcohol and cannabis; the number of days using alcohol first, cannabis first, alcohol last, and cannabis last; the number of days of simultaneous use), past-30-day alcohol and cannabis consequences, use frequency, and typical quantities used.

RESULTS

Each additional day of using alcohol first was associated with fewer past-30-day cannabis consequences. Each additional day of using cannabis first was associated with fewer alcohol-related consequences. Each additional day of using alcohol and cannabis on the same day and each additional day of simultaneous use were both associated with less cannabis used and alcohol consumed in a typical week.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

This study is among the first to identify associations between alcohol and cannabis order and outcomes (i.e., consequences and consumption). Results suggest that modifying which substance is used first on a given day could be a practical intervention strategy for individuals who co-use alcohol and cannabis.

Effects of combined use of alcohol and delta-9-tetrahydrocannibinol on working memory in Long Evans rats

The increase in social acceptance and legalization of cannabis over the last several years is likely to increase the prevalence of its co-use with alcohol. In spite of this, the potential for effects unique to co-use of these drugs, especially in moderate doses, has been studied relatively infrequently. We addressed this in the current study using a laboratory rat model of voluntary drug intake. Periadolescent male and female Long-Evans rats were allowed to orally self-administer ethanol, Î" 9 -tetrahydrocannibinol (THC), both drugs, or their vehicle controls from postnatal day (P) 30 to P47. They were subsequently trained and tested on an instrumental behavior task that assesses attention, working memory and behavioral flexibility. Similar to previous work, consumption of THC reduced both ethanol and saccharin intake in both sexes. Blood samples taken 14h following the final self-administration session revealed that females had higher levels of the THC metabolite THC-COOH. There were modest effects of THC on our delayed matching to position (DMTP) task, with females exhibiting reduced performance compared to their control group or male, drug using counterparts. However, there were no significant effects of co-use of ethanol or THC on DMTP performance, and drug effects were also not apparent in the reversal learning phase of the task when non-matching to position was required as the correct response. These findings are consistent with other published studies in rodent models showing that use of these drugs in low to moderate doses does not significantly impact memory or behavioral flexibility following a protracted abstinence period.

Associations between Alcohol-Free Sources of Reinforcement and the Frequency of Alcohol and Cannabis Co-Use among College Freshmen

Co-use of alcohol and cannabis is common among young adults in the United States. A behavioral economics framework indicates that greater engagement in substance-free sources of reinforcement may be protective against co-use frequency. The current study tested the association between proportionate alcohol-free reinforcement and the frequency of co-use among college freshmen. Participants (N = 86) were freshmen who enrolled in a freshman orientation course and completed surveys at the beginning of the semester. Past month alcohol use, cannabis use, and reinforcement from alcohol-free and alcohol-involved activities were assessed. A zero-inflated Poisson regression was used to test the association between proportionate alcohol-free reinforcement and days of co-use. The results indicated that proportionate alcohol-free reinforcement was negatively associated with co-use days in the count model when controlling for alcohol use days and gender as covariates (β: -3.28, p = 0.016). Proportionate alcohol-free reinforcement did not significantly differentiate individuals who did not engage in co-use in the zero-inflated model (β: -1.68, p = 0.497). The study suggested that greater proportionate alcohol-free reinforcement may be associated with lower engagement in the co-use of alcohol and cannabis among young adults. Increasing engagement in alcohol-free sources of reinforcement may be considered a target for co-use prevention or harm reduction efforts.

Concordance between substance use self-report and hair analysis in community-based adolescents

Background: Accurate drug use identification through subjective self-report and toxicological biosample (hair) analysis are necessary to determine substance use sequelae in youth. Yet consistency between self-reported substance use and robust, toxicological analysis in a large sample of youth is understudied.Objectives: We aim to assess concordance between self-reported substance use and hair toxicological analysis in community-based adolescents.Methods: Hair results by LC-MS/MS and GC-MS/MS and self-reported past-year substance use from an Adolescent Brain Cognitive Development (ABCD) Study subsample (N = 1,390; ages 9-13; 48% female) were compared. The participants were selected for hair selection through two methods: high scores on a substance risk algorithm selected 93%; 7% were low-risk, randomly selected participants. Kappa coefficients the examined concordance between self-report and hair results.Results: 10% of youth self-reported any past-year substance use (e.g. alcohol, cannabis, nicotine, and opiates), while a mostly non-overlapping 10% had hair results indicating recent substance use (cannabis, alcohol, non-prescription amphetamines, cocaine, nicotine, opiates, and fentanyl). In randomly selected low-risk cases, 7% were confirmed positive in hair. Combining methods, 19% of the sample self-reported substance use and/or had a positive hair sample. Kappa coefficient of concordance between self-report and hair results was low (kappa = 0.07; p = .007).Conclusions: Hair toxicology identified substance use in high-risk and low-risk ABCD cohort subsamples. Given low concordance between hair results and self-report, reliance on either method alone would incorrectly categorize 9% as non-users. Multiple methods for characterizing substance use history in youth improves accuracy. Larger representative samples are needed to assess the prevalence of substance use in youth.

The Role of Attentional Networks in Smoking Behavior Among Young Adults: Specific Contribution of Executive Control

INTRODUCTION

The exploration of cognitive impairments associated with tobacco use disorder has expanded during the last decades, centrally showing working memory and executive deficits among smokers. Despite their critical role in everyday life and in the smoking cessation process, attentional abilities have seldom been explored. Previous studies yielded discordant results, and the involvement of attentional deficits in smoking habits remains unclear.

AIMS AND METHODS

Capitalizing on the Attention Network Test, a theory-grounded task allowing the simultaneous but distinct evaluation of three attentional networks (alerting, orienting, executive control), we explored attentional abilities in three groups of 25 college students (nonsmokers, light smokers, heavy smokers), matched for demographic and psychopathological characteristics.

RESULTS

While light smokers did not present any deficit compared with nonsmokers, heavy smokers showed a specific impairment of the executive control subcomponent of attention, contrasting with preserved alerting and orienting attentional abilities. The executive control deficit was not related to current craving or to smoking duration.

CONCLUSIONS

Beyond the already explored memory and executive deficits, tobacco use disorder is associated with attentional impairments, characterized by a reduced ability to focus attentional resources on pertinent stimuli and resist to distractors interference. Given the assumed role of attentional impairments in smoking, our findings suggest that a critical step in future translational iterations is to develop neuropsychological rehabilitation programs tapping into the executive network of attention among smokers.

IMPLICATIONS

This study clarifies the presence and extent of attentional impairments in tobacco use disorder. We measured three attention networks (alerting, orienting, executive control) in light smokers, heavy smokers and matched healthy controls through a theory-grounded task (Attention Network Test). Heavy smokers (but not light ones) present a specific deficit for the executive control of attention. This deficit, uncorrelated with psychopathological comorbidities or current craving, appears directly related to smoking. Given the currently scattered literature on this topic, attentional processes deserve a thorough audit in tobacco use disorder, notably to develop specific neurocognitive rehabilitation.

Alcohol and cannabis co-use and longitudinal gray matter volumetric changes in early and late adolescence

BACKGROUND

Previous studies have characterized the impact of substance use on cerebral structure and function in adolescents. Yet, the great majority of prior studies employed a small sample, presented cross-sectional findings, and omitted potential sex differences.

METHODS

Using data based on 724 adolescents (370 females) curated from the NCANDA study, we investigated how gray matter volumes (GMVs) decline longitudinally as a result of alcohol and cannabis use. The impacts of alcohol and cannabis co-use and how these vary across assigned sex at birth and age were examined. Brain imaging data comprised the GMVs of 34 regions of interest and the results were evaluated with a Bonferroni correction.

RESULTS

Mixed-effects modeling showed faster volumetric declines in the caudal middle frontal cortex, fusiform, inferior frontal, superior temporal (STG), and supramarginal (SMG) gyri, at -0.046 to -0.138 cm3 /year in individuals with prior-year alcohol and cannabis co-use, but not those engaged in alcohol or cannabis use only. These findings cannot be explained by more severe alcohol use among co-users. Further, alcohol and cannabis co-use in early versus late adolescence predicted faster volumetric decline in the STG and SMG across assigned sex at birth.

CONCLUSIONS

Findings highlight the longitudinal impact of alcohol and cannabis co-use on brain development, especially among youth reporting early adolescent onset of use. The volumetric decline was noted in cortical regions in support of attention, memory, executive control, and social cognition, suggesting the pervasive effect of alcohol and cannabis co-use on brain development.

A bibliometric analysis of the cannabis and cannabinoid research literature

Background

Cannabis refers to a plant in the family Cannabaceae, which has been used medically, recreationally, and industrially. The last two decades, in particular, have seen a large increase in the volume of literature on this topic. The present bibliometric analysis aims to capture the characteristics of scholarly journal publications on the topic of cannabis and cannabinoid research.

Methods

Searches were run on the Scopus database on April 02, 2021, as follows “(TITLE (cannabi* OR hashish OR marijuana OR marihuana)) AND ( LIMIT-TO ( DOCTYPE,"ar" ) OR LIMIT-TO ( DOCTYPE,"re" ) )”. Results were exported on the same day to prevent discrepancies between daily database updates. Only “article” and “review” publication types were included; no further search limits were applied. The “article” publication type includes publications featuring original research, whereas “review” includes reviews and conference papers. The following data were collected: number of publications (in total and per year), authors, and journals; open access status; publications per journal; journals publishing the highest volume of literature and their impact factors, language of publication; document type; publication country; author affiliations; funding sponsors; most highly cited publications; and most highly published authors. Trends in this subset of publications were identified and presented. Bibliometric networks were constructed using the software tool VOSviewer.

Results

A total of 29 802 publications (10 214 open access), published by 65 109 authors, were published in 5474 journals from 1829 to 2021. The greatest number of publications was published over the last 20 years. The journal that published the largest number of publications was Drug and Alcohol Dependence (n = 705). The most productive countries included the USA (n = 12 420), the UK (n = 2236), and Canada (n = 2062); many of the most common institutional affiliations and funding sponsors originated from these countries.

Conclusions

The number of publications published on the topic of cannabis follows an upward trend. Over the past 20 years, the volume of cannabis research has grown steeply, which can be attributed to a large amount of funding dedicated to researching this topic. Future research should continue to investigate changes in the publication characteristics of emerging research, as the volume of publications on this topic is expected to rapidly grow.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42238-022-00133-0.

Simultaneous Alcohol/Cannabis Use and Driving Under the Influence in the U.S

INTRODUCTION

Alcohol and cannabis are commonly involved in motor vehicle crashes and fatalities. This study examines whether simultaneous use of alcohol/cannabis is associated with higher odds of reporting driving under the influence of alcohol and cannabis in the U.S.

METHODS

Drivers aged ≥16 years with any past-year alcohol and cannabis use in the 2016-2019 National Survey on Drug Use and Health (N=34,514) reported any past-year driving under the influence of alcohol-only, cannabis-only, both alcohol/cannabis, or not driving under the influence. Survey-weighted associations between simultaneous alcohol/cannabis use and each of the driving under the influence outcomes were computed adjusting for sociodemographics and daily alcohol/cannabis use. Analyses were conducted from November 2020 to September 2021.

RESULTS

In 2016-2019, 42% of drivers with past-year alcohol and cannabis use reported driving under the influence (8% alcohol-only, 20% cannabis-only, 14% alcohol/cannabis). Simultaneous alcohol/cannabis use was associated with 2.88-times higher adjusted odds of driving under the influence of cannabis-only (95% CI=2.59, 3.19) and 3.51-times higher adjusted odds of driving under the influence of both alcohol/cannabis (95% CI=3.05, 4.05), compared to not driving under the influence. Associations with driving under the influence of alcohol-only were unexpectedly in the opposite direction (adjusted conditional odds ratio=0.59, 95% CI=0.45, 0.79).

CONCLUSIONS

Overall, 2 in 5 drivers who used alcohol and cannabis reported driving under the influence of alcohol and/or cannabis. People reporting simultaneous alcohol/cannabis use were more likely to report cannabis-related driving under the influence. Prevention strategies should target individuals reporting simultaneous alcohol/cannabis use to reduce the occurrence of driving under the influence.

Adolescent Sibling Associations among Alcohol, Cannabis, and Sexual Risk Behavior: A Test of Interdependence

BACKGROUND

Although siblings are conceptualized as a salient social influence during adolescence, few studies have examined how adolescent siblings influence each other's substance use and risky sexual behavior. Objectives: In this study, we investigated the influence of alcohol use days, cannabis use days, and cannabis and alcohol co-use days on the sexual risk behavior of siblings while accounting for dyadic influence.

METHODS

At the baseline visit for a randomized controlled trial for adolescents referred due to parents' concerns about their substance use ("referred adolescents"; n = 99; M_age=15.95; 38.38% female), we assessed alcohol and cannabis use days as well as sexual risk behavior of the referred adolescents and their sibling (M_age=15.03; 51.52% female). We computed the number of days in the 30 days prior to the baseline that alcohol and cannabis use occurred on the same day. Using a cross-sectional actor partner interdependence model, we tested two models of how adolescents' substance use is associated with their own ("actor effect") and their siblings' ("partner effect") sexual risk behavior-one model for alcohol and cannabis use, and one model for daily co-use.

RESULTS

For referred adolescents and their siblings, within an individual, greater alcohol, cannabis, and daily co-use was significantly associated with sexual risk behavior (actor effects). Furthermore, more sibling co-use days was positively associated with referred adolescent sexual risk behavior (partner effect), representing interdependence.

CONCLUSION

These findings confirm the influence siblings have on one another's risky behavior in adolescence and have implications for prevention and intervention efforts for adolescent substance use.

Lower-Risk Cannabis Use Guidelines (LRCUG) for reducing health harms from non-medical cannabis use: A comprehensive evidence and recommendations update

BACKGROUND

Cannabis use is common, especially among young people, and is associated with risks for various health harms. Some jurisdictions have recently moved to legalization/regulation pursuing public health goals. Evidence-based 'Lower Risk Cannabis Use Guidelines' (LRCUG) and recommendations were previously developed to reduce modifiable risk factors of cannabis-related adverse health outcomes; related evidence has evolved substantially since. We aimed to review new scientific evidence and to develop comprehensively up-to-date LRCUG, including their recommendations, on this evidence basis.

METHODS

Targeted searches for literature (since 2016) on main risk factors for cannabis-related adverse health outcomes modifiable by the user-individual were conducted. Topical areas were informed by previous LRCUG content and expanded upon current evidence. Searches preferentially focused on systematic reviews, supplemented by key individual studies. The review results were evidence-graded, topically organized and narratively summarized; recommendations were developed through an iterative scientific expert consensus development process.

RESULTS

A substantial body of modifiable risk factors for cannabis use-related health harms were identified with varying evidence quality. Twelve substantive recommendation clusters and three precautionary statements were developed. In general, current evidence suggests that individuals can substantially reduce their risk for adverse health outcomes if they delay the onset of cannabis use until after adolescence, avoid the use of high-potency (THC) cannabis products and high-frequency/-intensity of use, and refrain from smoking-routes for administration. While young people are particularly vulnerable to cannabis-related harms, other sub-groups (e.g., pregnant women, drivers, older adults, those with co-morbidities) are advised to exercise particular caution with use-related risks. Legal/regulated cannabis products should be used where possible.

CONCLUSIONS

Cannabis use can result in adverse health outcomes, mostly among sub-groups with higher-risk use. Reducing the risk factors identified can help to reduce health harms from use. The LRCUG offer one targeted intervention component within a comprehensive public health approach for cannabis use. They require effective audience-tailoring and dissemination, regular updating as new evidence become available, and should be evaluated for their impact.

Changes in alcohol use by cannabis use status among adolescents and young adults in the United States: Emerging evidence for both substitution and complementarity

BACKGROUND

The majority of adolescents and young adults (AYA) who use cannabis also use alcohol. Although cannabis use is increasing in the United States (US), it is not known whether the increase contributes to either increased co-use of alcohol and cannabis (e.g., complementarity) or replacement of alcohol with cannabis (e.g., substitution). The current study estimated the prevalence of alcohol use by cannabis use status among US AYA ages 12 to 25 in 2018 and trends in alcohol use by cannabis use status from 2002 to 2018.

METHODS

Data were drawn from the 2002 to 2018 National Survey on Drug Use and Health public use data files. The analytic sample included AYA ages 12 to 25 (2018 sample, n = 26,924; total combined sample 2002 to 2018, n = 576,053). Linear and logistic regression models were used to estimate past-month alcohol use, daily alcohol use, and average quantity of alcohol consumed among AYA with and without past-month cannabis use from 2002 to 2018.

RESULTS

In 2018, any alcohol use and daily alcohol use were significantly more common among AYA who used cannabis use than those who did not use cannabis. Overall, any alcohol use, daily alcohol use, and average drinks per day declined from 2002 to 2018 among AYA irrespective of recent cannabis use. However, the decline in any alcohol use, daily alcohol use, and average alcohol drinks per day was more rapid among AYA who used cannabis (daily and nondaily) than those who did not use cannabis. The rate of decline in average alcohol drinks per day was also higher among AYA with daily compared to nondaily cannabis use.

CONCLUSIONS

Even with declines in alcohol use over time, drinking is much more common among AYA who report cannabis than those without recent cannabis use, which is consistent with complementarity. Yet, because the decline in alcohol use has been more rapid among AYA who use cannabis, there is also evidence of substitution. Thus, the current data on alcohol and cannabis use are consistent with both complementarity and substitution. However, these relationships may change as cannabis legalization expands over time.

Combined use of alcohol and cannabis: Introduction to the special issue

OBJECTIVE

Combined use of alcohol and cannabis has increased in recent years among certain age groups, and it is well established that individuals who use both alcohol and cannabis (especially if they use both at the same time) are at increased risk for substance-related harms relative to individuals who use only one substance. Far less attention has been placed on the patterns, predictors, and psychological processes associated with alcohol and cannabis co-use, which may inform prevention and intervention programming. Accordingly, this special issue was assembled to advance our understanding of the characteristics and consequences of combined use of alcohol and cannabis.

METHOD

In this introductory article, the Guest Editors present the background for this work and provide an overview of the 14 articles that comprise this special issue.

RESULTS

Studies contained in this special issue capitalize on a variety of methodologies, with a particular focus on investigating typologies of alcohol and cannabis co-use, clarifying motivational and social contexts of co-use, and tracking co-use in daily life via daily diary and ecological momentary assessment designs. Experimental and neuroimaging examinations of co-use are also included. Collectively, the studies generally provide evidence that combined use of alcohol and cannabis is associated with unique characteristics, predictors, consequences, and psychological processes relative to single-substance use.

CONCLUSIONS

The studies in this special issue provide new insight into combined use of alcohol and cannabis. They also highlight a number of promising avenues for future inquiry as the literature on alcohol and cannabis co-use continues to grow. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Alcohol and Cannabis Use and the Developing Brain

PURPOSE

Alcohol and cannabis are the most commonly used substances during adolescence and are typically initiated during this sensitive neurodevelopmental period. The aim of this review is to provide a comprehensive overview of the most recent literature focused on understanding how these substances affect the developing brain.

SEARCH METHODS

Articles included in this review were identified by entering 30 search terms focused on substance use, adolescence, and neurodevelopment into MEDLINE, Embase, PsycINFO, ProQuest Central, and Web of Science. Studies were eligible for inclusion if they longitudinally examined the effect of adolescent alcohol and/or cannabis use on structural or functional outcomes in 50 or more participants.

SEARCH RESULTS

More than 700 articles were captured by the search, and 43 longitudinal studies met inclusion criteria, including 18 studies focused on alcohol use, 13 on cannabis use, and 12 on alcohol and cannabis co-use.

DISCUSSION AND CONCLUSIONS

Existing studies suggest heavy alcohol and cannabis use during adolescence are related to small to moderate disruptions in brain structure and function, as well as neurocognitive impairment. The effects of alcohol use include widespread decreases in gray matter volume and cortical thickness across time; slowed white matter growth and poorer integrity; disrupted network efficiency; and poorer impulse and attentional control, learning, memory, visuospatial processing, and psychomotor speed. The severity of some effects is dependent on dose. Heavy to very heavy cannabis use is associated with decreased subcortical volume and increased frontoparietal cortical thickness, disrupted functional development, and decreased executive functioning and IQ compared to non-using controls. Overall, co-use findings suggest more pronounced effects related to alcohol use than to cannabis use. Several limitations exist in the literature. Sample sizes are relatively small and demographically homogenous, with significant heterogeneity in substance use patterns and methodologies across studies. More research is needed to clarify how substance dosing and interactions between substances, as well as sociodemographic and environmental factors, affect outcomes. Larger longitudinal studies, already underway, will help clarify the relationship between brain development and substance use.