Cannabis-only Users Research Articles

Biobehavioral and affective stress responses during nicotine withdrawal: Influence of regular cannabis co-use.

Co-use of cannabis is increasing in nicotine users and presents additional challenges in addressing nicotine dependence. This study examined the links between regular co-use of cannabis and nicotine with biobehavioral and affective changes in response to stress during nicotine withdrawal and ad libitum use. Participants (N = 79) who regularly used nicotine-only, cannabis-only, both substances, or neither substance were invited to attend two laboratory stress assessment sessions. For nicotine users, one session occurred during ad libitum nicotine use and one occurred after abstinence from nicotine. During the stress sessions, participants provided saliva samples for cortisol assay and completed measures of subjective states. Cardiovascular measures were collected during resting baseline, exposure to acute stressors, and a recovery rest period. Nicotine-only users had higher average cortisol levels in the second lab session (nicotine withdrawal) relative to the first lab session (ad libitum nicotine use). Compared to nicotine non-users, nicotine users reported less positive affect and exhibited attenuated cortisol and systolic blood pressure (BP) stress responses. Cannabis users exhibited exaggerated diastolic BP responses to stress compared to cannabis non-users, and co-users of nicotine and cannabis had higher levels of cannabis craving than cannabis-only users (p < .01). This study partially replicated earlier findings on the effects of chronic nicotine use and provided novel results regarding the influence of cannabis co-use on physiological and affective responses to stress in nicotine users during nicotine withdrawal.

Altered functional connectivity and oscillatory dynamics in polysubstance and cannabis only users during visuospatial processing.

Cannabis use is often associated with the use of other psychoactive substances, which is subsequently linked to an increased risk for addiction. While there is a growing body of neuroimaging literature investigating the cognitive effect of long-term cannabis use, very little is known about the potential additive effects of cannabis polysubstance use. Fifty-six adults composed of 18 polysubstance users (i.e., cannabis plus at least one other illicit substance), 19 cannabis-only users, and 19 nonusers completed a visuospatial attention task while undergoing magnetoencephalography. A data-driven approach was used to identify oscillatory neural responses, which were imaged using a beamforming approach. The resulting cortical regions were probed for group differences and used as seeds for whole-brain connectivity analysis. Participants exhibited robust theta, alpha, beta, and gamma responses during visuospatial processing. Statistical analyses indicated that the cannabis-only group had weaker occipital theta relative to the nonusers, and that both polysubstance and cannabis-only users had reduced spontaneous gamma in the occipital cortices during the pre-stimulus baseline period relative to nonusers. Finally, functional connectivity analyses revealed that polysubstance users had sharply reduced beta connectivity between occipital and prefrontal, as well as occipital and left temporal cortices. Cannabis use should be considered in a polysubstance context, as our correlational design suggests differences in functional connectivity among those who reported cannabis-only versus polysubstance use in occipital to prefrontal pathways critical to visuospatial processing and attention function. Future work should distinguish the effect of different polysubstance combinations and use more causal designs.

Offering an Alternative to Persons with Chronic Pain: How Access to Cannabis May Provide an Off-Ramp from Undesired Prescription Opioid Use.

Chronic pain (CP) is experienced by as many as 50 million Americans and can negatively impact physical and mental health. Prescribing opioids is the most common approach to address moderate to severe CP though these potent analgesics are associated with a significant number of side effects. One alternative some Americans are turning to for CP management is cannabis. In addition to serving as an alternative, many individuals with CP use cannabis in addition to using prescription opioids. This study examined individuals with CP who enrolled in the state of Illinois' opioid diversion program, the Opioid Alternative Pilot Program (OAPP), which offers individuals aged 21 and older a separate pathway to access medical cannabis if they have or could receive a prescription for opioids as certified by a licensed physician. Cross-sectional survey data were collected from 450 participants. We described participants and compared those who use only cannabis with those who use cannabis and opioids. While 16% of the respondents were cannabis-only users, 84% of the respondents were co-users of opioids and cannabis. Both groups considered opioid use risky (100% cannabis-only, 89% co-users,). The majority (73%) of respondents sought to completely stop or never start using opioids for CP. Cannabis-only users reported lower levels of pain compared to co-users. Co-users (85%) were more likely to have their routine provider as a cannabis certifying physician than cannabis-only users (69%). With increasing clinical evidence, legalization and acceptance, researchers should continue to examine how cannabis may be a viable alternative to reduce the risk of prescription opioid side effects, misuse, or dependence. Our findings also inform health care providers and state policymakers who increasingly are being asked to consider how cannabis may reduce the potential for harmful outcomes among persons with CP who use prescription opioids.

Independent and concurrent cannabis use with alcohol, cigarettes, and other substances among college students: Rates and consequences

Objective: The purpose of this study was to examine patterns of concurrent cannabis and other substance use and their differential associations with cannabis-related problems and academic outcomes in college students. Participants: Participants were undergraduate students (N = 263; M age = 19.1 years; 61.2% female) who were eligible if they used cannabis at least 3 days in the past month (M = 10.1 days). Method: Substance use, academic-related outcomes, and measures of Cannabis Use Disorder (CUD) severity and problems were obtained in an online survey. Results: The five groups evaluated were cannabis-only users (5.3%), cannabis and alcohol (47.1%), cannabis, alcohol and cigarettes (16.7%), cannabis, alcohol and other substances (14.8%), or all-substances (16%). Cannabis-only and all-substance users reported using cannabis most frequently (ps ≤ .034), but only the latter reported greater CUD severity, problems, and poorer academic outcomes. Discussion: College student polysubstance users may be at increased risk for poorer outcomes compared to cannabis-only users and other groups.

Effects of regular cannabis and nicotine use on acute stress responses: chronic nicotine, but not cannabis use, is associated with blunted adrenocortical and cardiovascular responses to stress.

Cannabis is one of the most prevalent substances used by tobacco smokers and, in light of the growing list of states and territories legalizing cannabis, it is expected that co-use of cannabis and nicotine will escalate significantly and will lead to continuing challenges with tobacco use. This study was conducted to examine the interactive effects of chronic cannabis and nicotine use on adrenocortical, cardiovascular, and psychological responses to stress and to explore sex differences in these effects. Participants (N = 231) included cannabis-only users, nicotine-only users, co-users of both substances, and a non/light-user comparison group. After attending a medical screening session, participants completed a laboratory stress session during which they completed measures of subjective states, cardiovascular responses, and salivary cortisol during baseline (rest) and after exposure to acute stress challenges. Nicotine use, but not cannabis use, was associated with blunted cortisol and cardiovascular responses to stress across both men and women. Men exhibited larger cortisol responses to stress than women. Co-users had significantly larger stress-related increases in cannabis craving than cannabis-only users. Cannabis users reported smaller increases in anxiety during stress than cannabis non/light-users, and both male nicotine-only users and male cannabis-only users experienced significantly smaller increases in stress than their non/light-user control counterparts. This study replicates and extends earlier research on the impacts of sex and nicotine use on stress responses, and it provides novel findings suggesting that when co-used with nicotine, cannabis use may not confer additional alterations to physiological nor subjective responses to stress. Co-use, however, was associated with enhanced stress-related craving for cannabis.

In-home cannabis smoking more prevalent than in-home tobacco smoking among 2019 Global Drug Survey respondents

Purpose of the ResearchEarly evidence from studies of home smoking policies suggests that in-home cannabis smoking is more often allowed than in-home tobacco smoking, but there are not yet data on whether cannabis is more often smoked in the home compared to tobacco, or whether in-home cannabis and tobacco smoking differs by usage status. Using cross-sectional data from over 100,000 sentinel drug users from 17 countries, we compared cannabis and tobacco smoking in the homes of Global Drug Survey 2019 respondents who currently used cannabis only, tobacco only, both tobacco and cannabis, or neither. Principal ResultsComplete data on cannabis and tobacco use and in-home smoking were available for 107,272 adults (average age = 30 ± 12, 34% women, countries with the three highest response rates; Germany = 32%, USA = 10%, New Zealand = 9%). In total, 53.6% and 50.6% of respondents reported past-year cannabis and tobacco smoking in their home respectively. Stratifying respondents into current cannabis-only users, tobacco-only users, dual users, and non-users, past-year in-home cannabis smoking was more prevalent (78.8%) among cannabis-only users than was in-home tobacco smoking (67.9%) among tobacco-only users. Among dual users, past-year in-home cannabis smoking (82.8%; 95%CI = 80%-86%) was higher than in-home tobacco smoking (75.9%; 95%CI = 69%–81%; p < 0.001). In-home cannabis and tobacco smoking was similar among non-users (20.2% and 20.5%, respectively). Major ConclusionsPast-year in-home cannabis smoking was more prevalent than tobacco smoking in the homes of participants who used cannabis and/or tobacco, supporting our speculation that in-home cannabis smoking might be more socially acceptable than in-home tobacco smoking.

Psychiatric Hospitalization and Length of Stay Differences in Cannabis Users and Non-Users with a Primary Discharge Diagnosis of Schizophrenia or Schizoaffective Disorder

Background The effects of cannabis use in vulnerable persons with schizophrenia or schizoaffective disorder, continues to be elucidated. Methods We compared 55 cannabis-only users (Group 1) with 462 non-substance users (Group 2) on measures of length of stay and number of psychiatric hospitalizations with a primary discharge diagnosis of schizophrenia or schizoaffective disorder using the Wilcoxon-Mann-Whitney non-parametric test for non-normal distributions, analysis of variance (ANOVA), and Poisson regression analysis. Results Group 1 had a mean length of stay of 6.15 days (sd = 5.32 days) and Group 2 had a mean length of stay of 8.66 days (sd = 11.14 days) (i.e. Wilcoxon-Mann-Whitney, p = .0347; log-transformed ANOVA, p = .0203). This difference was no longer statistically significant when controlling for three covariates (p = .1543). Poisson regressions for the mean number of admissions (1.84) were not statistically significant. Conclusions Cannabis use may not be a good predictor of length of stay, once covariates are considered, and mean number of hospitalizations in hospitalized patients with schizophrenia or schizoaffective disorder.

Between- and within-group effects of alcohol and cannabis co-use on AUD/CUD in the NSDUH 2002–2019

BackgroundAlcohol and cannabis co-use is a between-group risk factor for heavier drinking and negative consequences, but only one study has tested links between co-use and AUD. In addition, few studies focus on risk profiles within co-users, despite heterogeneity in levels of co-use. The current study tested between-group (co-users vs. alcohol-/cannabis-only users) and within-group (patterns of co-use) risk profiles for AUD and CUD in a large, nationally representative sample. MethodsData from the 2002–2019 National Study on Drug Use and Health (NSDUH) were used for analyses (N = 1,005,421). Analyses tested 1) whether co-users had greater odds of AUD/CUD than alcohol- and cannabis-only users, respectively, 2) whether there were latent profiles of co-use patterns within co-users, and 3) whether profile membership conferred within-group risk for AUD/CUD. ResultsCo-users were at 3.38 greater odds of having an AUD, but co-use did not confer risk for CUD. Within co-users, five latent profiles emerged: weekly alcohol/cannabis use, weekly alcohol/monthly cannabis, weekly cannabis/occasional alcohol, weekly alcohol/occasional cannabis, and occasional use of both. Multiple comparisons suggested that, generally as frequency of each substance use increased, odds of both AUD and CUD became greater. ConclusionsPrimary alcohol users who also use cannabis are at risk for AUD, but the opposite effect was not observed in primary cannabis users. Higher frequency of each substance also conferred risk within co-users for both AUD and CUD. Findings add novel contributions that should be considered within both alcohol and cannabis use interventions. Future studies using prospective data are needed.

A Preliminary Study on the Influence of Cannabis and Opioid Use on Weight Loss and Mental Health Biomarkers Post-weight Loss Surgery.

A subpopulation of weight loss surgery (WLS) patients endorse cannabis and/or opioid use; however, impact on post-WLS anxiety and depression is unclear. This study examined the influence of the independent and combined use of cannabis and opioids on (1) depression and anxiety, (2) duodenum serotonin and cortisol, and (3) total percent weight loss. A cross-sectional analysis was conducted among patients (N =18) who had biomarkers of serotonin and cortisol collected from the duodenum during WLS. Cannabis and opioid use was determined by self-reported lifetime, past-year, and past 30-day use. The Beck Anxiety Inventory and Depression Inventory-II assessed depression and anxiety symptoms. Total percent weight loss was calculated from pre-WLS and post-WLS weight (kg). Chi-squared analyses and t tests were conducted. Over a quarter (27.8%) were cannabis-only users and 16.7% used a combination of cannabis and opioids. None reported using only opioids in this sample. Combination users presented with greater depressive symptoms (22.7%, p= 0.01) and greater total percent weight loss (34.1%, p= 0.04) than cannabis users (7.8, 23.2%, respectively). Cannabis users had greater serotonin (p= 0.02) and cortisol (p= 0.01) levels than combination users and never users. Cannabis users had greater cortisol levels than never users and combination users. Combination users had greater weight loss and depression symptoms than cannabis users. Future studies should consider a larger sample size, utilization of a cohort design to address causality, and examination of the type, dose, and route of cannabis and opioid administration to further understand the impact of the combined use of cannabis and opioids post-WLS.

Unraveling the role of cigarette use in neural cannabis cue reactivity in heavy cannabis users.

Cue reactivity is an important biomarker of cannabis use disorder (CUD). Despite high rates of cigarette and cannabis co‐use, its role in cannabis cue reactivity remains unclear. Using a visual functional magnetic resonance imaging cue reactivity paradigm, we investigated interactive effects of cannabis and cigarette use on cannabis cue relative to cigarette and neutral cue reactivity in a priori regions of interest—the amygdala, striatum, anterior cingulate cortex (ACC), ventral tegmental area (VTA), and orbitofrontal cortex—and a whole‐brain analysis. In our sample of cannabis users and controls closely matched on cigarette use, significant interactions between cannabis and cigarette use status emerged in the amygdala, striatum, ACC, frontal pole, and inferior frontal gyrus. Cannabis‐only users showed heightened cue reactivity in the amygdala compared with nonusing controls. Co‐users did not show heightened cue reactivity compared with cigarette smoking controls, although cue‐induced VTA activity was positively correlated with grams per week of cannabis. Cigarette smoking controls showed unexpectedly heightened cue reactivity compared to co‐users and nonsmoking controls. These findings and the high prevalence of cannabis and cigarette co‐use underscore the importance of considering cigarette smoking status when investigating the role of cue reactivity in heavy cannabis use.

Genome-wide DNA methylation analysis of heavy cannabis exposure in a New Zealand longitudinal cohort

Cannabis use is of increasing public health interest globally. Here we examined the effect of heavy cannabis use, with and without tobacco, on genome-wide DNA methylation in a longitudinal birth cohort (Christchurch Health and Development Study, CHDS). A total of 48 heavy cannabis users were selected from the CHDS cohort, on the basis of their adult exposure to cannabis and tobacco, and DNA methylation assessed from whole blood samples, collected at approximately age 28. Methylation in heavy cannabis users was assessed, relative to non-users (n = 48 controls) via the Illumina Infinium® MethylationEPIC BeadChip. We found the most differentially methylated sites in cannabis with tobacco users were in the AHRR and F2RL3 genes, replicating previous studies on the effects of tobacco. Cannabis-only users had no evidence of differential methylation in these genes, or at any other loci at the epigenome-wide significance level (P < 10−7). However, there were 521 sites differentially methylated at P < 0.001 which were enriched for genes involved in neuronal signalling (glutamatergic synapse and long-term potentiation) and cardiomyopathy. Further, the most differentially methylated loci were associated with genes with reported roles in brain function (e.g. TMEM190, MUC3L, CDC20 and SP9). We conclude that the effects of cannabis use on the mature human blood methylome differ from, and are less pronounced than, the effects of tobacco use, and that larger sample sizes are required to investigate this further.

Prevalence and Correlates of Concurrent and Simultaneous Cannabis and Cigarette Use among Past-Year Cannabis-Using US College Students

Background: Cannabis and tobacco use are significant public health concerns among young adults, with concurrent (in the same time period) and simultaneous (at the same time so the effects overlap) use of both substances on the rise. Few studies have examined these behaviors among college students. Objective: We examined the prevalence of concurrent and simultaneous cannabis and cigarette (combustible or electronic) use among a sample of college students and characterized the psychosocial predictors of concurrent and simultaneous use compared to using cannabis alone. Methods: Data on past-3 months cannabis and cigarette use were collected on 1352 college students who were past-year cannabis and alcohol users yielding four groups: cannabis-only users (n = 686), concurrent cannabis and cigarette users (CCAC; n = 235), simultaneous cannabis and cigarette users (SCAC; n = 293), and non-recent users of either substance (n = 138). Multinomial logistic regression analyses were utilized to predict group membership. Results: Relative to the cannabis-only group, White, compared to Non-White students, males, compared to females, frequent, compared to infrequent, alcohol users, including those who used alcohol simultaneously with cigarettes, and illicit drug users were more likely to belong to the CCAC or SCAC group. Conclusions: Findings suggest the need for unique intervention efforts to prevent onset or reduce co-use among male and White students as well as illicit drug users and frequent alcohol users.

Tobacco and cannabis co-use and interrelatedness among adults

Cannabis and tobacco co-use is prevalent, but consensus regarding the reasons for co-use among adults and the degree of interrelatedness between these substances is lacking. Reasons for co-use have been explored with younger users, but little data exists for more experienced users with entrenched patterns of co-use. The goal of this study was to examine characteristics and patterns of cannabis-tobacco co-use among adults in the Southeastern United States (US), where there is a legal landscape of generally restrictive cannabis legislation coupled with more permissive tobacco control compared to other US regions. Participants (N = 432) were regular cannabis users recruited through Amazon Mechanical Turk. Measures included demographics, patterns of cannabis and tobacco use, and reasons for co-use. Within this sample, 42% were current users of tobacco (n = 182). Cannabis-tobacco co-users were older and had more years of cannabis use than cannabis-only users. Among the co-using sub-sample, there was little consistency in the reasons for co-use, suggesting individual differences in the use of both substances. High levels of cannabis-tobacco interrelatedness (i.e., temporally concurrent use) were associated with smoking more cigarettes (tobacco) per day and greater nicotine dependence scores when compared to users with low levels of interrelatedness. Though these results are limited by a small sample size and generalizability issues, there were individual differences in cannabis-tobacco relatedness, which may be of importance when considering treatment strategies for cannabis, tobacco, or both. With additional research, personalized strategies adapted to cannabis-tobacco relatedness profiles among co-users may be warranted as a treatment strategy.

The frequency of hospitalizations and length of stay differences between schizophrenic and schizoaffective disorder inpatients who use cannabis

ABSTRACTBackground: The literature on the effects of cannabis use by patients with schizophrenia is variable.Aims: To determine whether there are differences among urine-screened cannabis-only users, polysubstance users using cannabis, and nonusers on the number of inpatient hospitalizations and length of stay for patients with schizophrenia or schizoaffective disorder.Method: This study (N = 116) included patients who tested positive for only cannabis (n = 20, Group 1); tested positive for cannabis and had a history of other substance use (n = 43, Group 2); and had negative drug screens (n = 53, Group 3).Results: Groups 1 and 2 had significantly lower numbers of hospitalizations than Group 3 without controlling for any other factors, and non-significantly lower lengths of stay than Group 3.Conclusions: Our results do not support the hypothesis that cannabis exacerbates psychotic symptoms in patients with schizophrenia or schizoaffective disorder. Our study is unique in that it utilized objective urine drug screens.

The lows of getting high: sentinel surveillance of injuries associated with cannabis and other substance use

ObjectivesCannabis is a widely used illicit substance that has been associated with acute injuries. This study seeks to provide near real-time injury estimates related to cannabis and other substance use from the electronic Canadian Hospitals Injury Reporting and Prevention Program (eCHIRPP) database.MethodsData from the eCHIRPP database, years 2011 to 2016, were analyzed via data mining, descriptive, logistic regression, and sensitivity analyses. Drug use trends over time for cannabis and/or other substances (alcohol, illicit drugs, and medications) were assessed. Descriptive statistics (intent, external cause, and nature of injury) and proportionate injury ratios (PIR) associated with cannabis use are presented.ResultsCannabis use was observed in 184 cases/100,000 eCHIRPP cases, and related injuries were mostly identified as unintentional (66.8%). Poisoning (68.5%) and intoxication (69.4%) were the external cause and nature of injury most associated with these events, and hospitalization was recorded for 14.3% of cases. Per 100,000 eCHIRPP cases, cannabis was used alone in 72.4 cases, and in combination with alcohol, illicit drugs, or medications in 74.6 cases, 11.3 cases, and 7.9 cases, respectively. Relative to non-use, the PIR of hospitalization was not significant for cannabis-only users of either sex (males: PIR 1.0, 95% CI 0.6–1.7, females: PIR 0.9, 95% CI: 0.5–1.7).ConclusionCannabis use injuries are rare, but can occur when cannabis is used with or without other substances. As Canada considers legislative changes, our finding of cases related to unintentional injury, poisoning, and intoxication suggests areas that might benefit from health literacy efforts.

Increasing use of cannabis among arrested drivers in Norway

ABSTRACTObjective: The availability of cannabis in Norway seems to have increased according to seizures by customs and police. On the other hand, national population surveys have not found any increase in self-reported use of cannabis. This investigation aimed at studying trends in cannabis use among suspected drug-impaired drivers apprehended by the police in Norway.Methods: A time series observational study of cannabis use among all drivers tested for drugs during 2000–2015 was performed. Descriptive analyses of trends in frequencies and combined use of cannabis with other drugs or alcohol for different age groups and gender were conducted.Results: Tetrahydrocannabinol (THC) is the main psychoactive substance in cannabis and was detected in blood samples from 18,767 suspected drug-impaired drivers. The annual number of THC findings increased during the years 2000–2015 for all age groups. For cannabis-only users, young drivers aged 20–29 years dominated during the whole period, whereas for multidrug–cannabis users the median age increased steadily during 2000–2015. After 2009, the annual increase in THC findings escalated; THC-only findings increased the most.Conclusions: Increasing numbers of THC-positive drivers were found among all age groups and genders; the strongest trend was observed between 2009–2015 for young drivers testing positive only for THC.

Characteristics of Cannabis-Only and Other Drug Users Who Visit the Emergency Department

Emergency department (ED) settings have gained interest as venues for illegal drug misuse prevention and intervention, with researchers and practitioners attempting to capitalize on the intersection of need and opportunity within these settings. This study of 686 adult patients visiting two EDs for various reasons who admitted drug use compared daily cannabis-only users, nondaily cannabis-only users, and other drug users on sociodemographic and drug-related severity outcomes. The three drug use groups did not differ on most sociodemographic factors or medical problem severity scores. Forty-five percent of the sample was identified as having a drug use problem. ED patients who used drugs other than cannabis were at particular risk for high drug use severity indicators and concomitant problems such as psychiatric problems and alcohol use severity. However, 19–29% of cannabis-only users were identified as having problematic drug use. Furthermore, daily cannabis-only users fared less well than nondaily cannabis users with regard to drug use severity indicators and self-efficacy for avoiding drug use. Results may assist emergency medicine providers and medical social workers in matching patients to appropriate intervention. For example, users of drugs other than cannabis (and perhaps heavy, daily cannabis-only users) may need referral to specialty services for further assessment. Enhancement of motivation and self-efficacy beliefs could be an important target of prevention and treatment for cannabis-only users screened in the ED.

Drug use disorders in the polydrug context: new epidemiological evidence from a foodborne outbreak approach.

As epidemiologists studying foodborne illness outbreaks, we do not ask luncheon attendees to say which food caused their illnesses. Instead, we use measurement and analysis methods to estimate food-specific risk variations. Here, we adapt the foodborne outbreak approach to develop new estimates of drug use disorder risk for single-drug and polydrug users, without attributing the syndrome to a specific drug when multiple drugs have been used. We estimate drug use disorder risk for cannabis-only users as a reference value. We then derive comparative relative risk estimates for users of other drug subtypes, including polydrug combinations. Data are from the 2002 to 2003 U.S. National Comorbidity Survey Replication, a nationally representative sample of household residents (18+ years), with standardized drug use and drug dependence assessments. Multiple logistic regression provides odds ratio estimates of relative risk. With this approach, for every 1000 cannabis-only users, an estimated 17 had become cases (1.7%). By comparison, polydrug users and cocaine-only users had much greater cumulative incidence (>10%), even with adjustment for covariates and local area matching (P < 0.001). Using this approach, we find exceptionally low risk for cannabis-only users and greater risk for polydrug and cocaine-only users.

Trends in the co-occurrence of tobacco and cannabis use in 15-year-olds from 2002 to 2010 in 28 countries of Europe and North America.

Cannabis and tobacco use frequently co-occur. Adolescents who consume both substances experience more respiratory distress and psychosocial problems and are less likely to stop compared with those who use either tobacco or cannabis alone. This study examined time trends in tobacco and cannabis use among 15-year-olds in Europe and North America between 2002 and 2010. Twenty-eight countries were included and merged into six regions based on their welfare systems. Adolescents (n = 142 796) were divided in four 'user groups': 'no-users', 'tobacco and cannabis users', 'tobacco-only users' and 'cannabis-only users'. Prevalence rates are reported by study-wave and region. Logistic regressions with study wave as independent variable were used to study trends in the user groups and regions. Interaction effects between time and gender were considered. Overall, tobacco use, and concurrent tobacco and cannabis use decreased by 3 and 3.7%, respectively, but prevalence rates varied by region. Only in North America, an interaction effect between time and gender was found in tobacco and cannabis users. Although this study demonstrates a decrease in tobacco and cannabis use in most regions, it also shows that the use of both substances is related. Therefore, studying the co-occurring use of tobacco and cannabis is necessary.

The Co‐Use of Tobacco and Cannabis Among Adolescents Over a 30‐Year Period

This study explores the patterns of use and co-use of tobacco and cannabis among Ontario adolescents over 3 decades and if characteristics of co-users and single substance users have changed. Co-use trends for 1981-2011 were analyzed using the Centre for Addiction and Mental Health Ontario Student Drug Use and Health Survey, which includes 38,331 students in grades 7, 9, and 11. A co-user was defined as someone reporting daily tobacco and/or cannabis use in the past month. Trends over time (by gender and academic performance) were analyzed with logistic regression. The prevalence of tobacco-only use, cannabis-only use, and co-use fluctuated considerably. During 1981-1993, there were more tobacco-only users than co-users and cannabis-only users; since 1993 the prevalence of tobacco use has decreased dramatically. Co-use prevalence peaked at 12% (95% confidence interval: 9, 15) in 1999, when prevalence of overall use of both substances was highest. In 2011, 92% of tobacco users also used cannabis, up from 16% in 1991. In 2011 nearly all students who smoke tobacco daily also use cannabis. Non-regular use of either substance is highest now compared with the past 3 decades. Contemporary tobacco and cannabis co-users are significantly different than past users. Youth prevention programs should understand the changing context of cannabis and tobacco among youth.