Associations Between Cannabis Use and Mental Distress in Young People: A Longitudinal Study

PURPOSE

Despite a large number of studies on the relation between cannabis use and mental distress in adolescence, results are inconclusive regarding the nature of this association. The aim of the present study is to expand this body of research by analyzing the within-person association between changes in cannabis use and changes in mental distress among young people.

METHODS

We used longitudinal data from a national sample of young people in Norway. The cohort was assessed in 1992 (T1), 1994 (T2), 1999 (T3), and 2005 (T4). The cumulative response rate was 60%. Respondents who participated in all four waves, aged 11-18 years at T1 (N = 1,988) were analyzed. Within-person association between changes in cannabis use and changes in mental distress in terms of symptoms of depression, anxiety, suicidal ideation, and deliberate self-harm were estimated by applying fixed-effects modeling.

RESULTS

For males, an increase in cannabis use from no use to more than 10 times/year was significantly associated with increased risk for anxiety (relative risk [RR]: 1.72, p = .009), depressed mood (RR: 1.49, p < .001), and suicidal ideation (RR: 3.43, p = .012). For females, the corresponding increase in cannabis use yielded an increased risk for anxiety (RR: 1.38, p = .023) and suicidal ideation (RR: 2.47, p = .002).

DISCUSSION

Increased cannabis use during adolescence and young adulthood seem to increase the risk for symptoms of mental distress. Although the associations appear to be more pronounced among males, it was only for depression that there was a statistically significant gender difference in the association.

Trends in Tobacco Use among 9th Graders in Sweden, 1991-2020

Tobacco use was measured with self-reports of lifetime use of cigarettes and snus to examine trends in tobacco use among Swedish 9th graders over the period 1991-2020. Annual school surveys with nationally representative samples of 9th-grade students in Sweden covering the period 1991-2020 with a total sample of 163,617 students. We distinguished between the use of cigarettes only, use of snus only, dual use (use of both cigarettes and snus), and total tobacco use (use of any of these tobacco products). In addition to a graphical description of trends in the various measures of tobacco use, the correlation between these trends was calculated with the Pearson correlation coefficient (Rxy). The prevalence of total tobacco use declined from 72% in 1991 to 36% in 2020. The declining trend in total tobacco use was positively correlated with the trend in dual use (Rxy = 0.98) and the trend in cigarette use only (Rxy = 0.87). The trend in total tobacco use was, on the other hand, negatively correlated with snus use only (Rxy = -0.41), and snus use only was negatively correlated with cigarette use only (Rxy = -0.71). The situation became different after 2017 when total tobacco use increased as a result of an increasing prevalence of snus use. The sharp decline in tobacco use among 9th graders in Sweden over the past three decades is driven by declining cigarette use. The correlations between the various forms of tobacco use suggest that snus use may have contributed to the decline in cigarette use and, by that, overall tobacco use. The situation changed after 2017 when a sharp rise in snus use seems to have increased total tobacco use among adolescents in Sweden. A possible explanation behind this development is the introduction of a new form of snus called "All white snus", which was introduced in Sweden in 2014.

Are the well-off youth in Sweden more likely to use cannabis?

INTRODUCTION AND AIMS

Results from previous research are inconsistent regarding the association between socioeconomic status (SES) and cannabis use among adolescents. Since there are risks associated with cannabis use, a social gradient in cannabis use may contribute to reproducing socioeconomic differences in life opportunities. The aim of this study was to assess the association between childhood SES and cannabis use among youth in Sweden.

DESIGN AND METHODS

We used repeated cross-sectional data from three waves (2014-2016) of the Swedish national school survey among 11th graders. The analysis encompassed 9497 individuals in 668 school classes. Childhood SES was measured through parents' highest education, as reported by the students. Cannabis use was measured in terms of lifetime use and frequency of use. Data were analysed using multi-level mixed-effects Poisson regression.

RESULTS

Adolescents with at least 1 parent with university/college education had 17% (incidence rate ratio 1.17, confidence interval 1.05, 1.30) higher risk of lifetime use of cannabis compared with those whose parents had no university/college education, adjusting for sex, SES of the school environment, academic orientation, truancy, risk assessment and parental permissiveness. Among life-time users of cannabis, risk for frequent cannabis use was 28% (incidence rate ratio 0.72, confidence interval 0.53, 0.97) lower for those with at least 1 parent with university or college education.

DISCUSSION AND CONCLUSIONS

Childhood SES, in terms of parental education, was associated with cannabis use among Swedish adolescents. Adolescents from families with lower SES were less likely to ever try cannabis, but at higher risk for frequent use.

Are changes in drinking related to changes in cannabis use among Swedish adolescents? A time-series analysis for the period 1989-2016

AIMS

To examine if changes in alcohol consumption are associated with changes in cannabis use among Swedish adolescents in a period of diverging trends, and to investigate if cannabis and alcohol act as complements or substitutes.

DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS

Data comprise a nationally representative annual school survey of alcohol and drug habits among Swedish 9th-grade students (aged 15-16 years) covering years 1989-2016 (n = 149 603). Alcohol and cannabis use were measured concurrently and alcohol consumption was measured in litres of 100% alcohol per year. Frequency of cannabis use was transformed into a mean using category mid-points. Autoregressive integrated moving average (ARIMA) time-series analysis was used to estimate the association between cannabis and alcohol use. To elucidate changes in the association during the study period, two subperiods (2000-16 and 1989-99) were analysed.

FINDINGS

There was a positive and statistically significant association between changes in alcohol consumption and changes in frequency of cannabis use among cannabis users for the period 1989-2016. A 1-litre increase in mean alcohol consumption was associated with a 0.28 increase in frequency of cannabis use (P = 0.010). The corresponding increase for the period 1989-99 was 0.52 (P = 0.003). When restricting the analysis to 2000-16, the association was not statistically significant (P = 0.735). When analysing all adolescents we found no statistically significant association between changes in alcohol consumption and changes in frequency of cannabis use.

CONCLUSIONS

From 1989 to 2016 there appears to be a positive association between alcohol and cannabis consumption among Swedish adolescents who use cannabis. This association seems to have become weaker over time, suggesting that alcohol and cannabis are neither substitutes nor complements among Swedish adolescents and that the recent decline in youth drinking is not associated with the increase in frequency of cannabis use.

Individual and school-class correlates of youth cannabis use in Sweden: A multilevel study

Background and aims:

The school-class context is a crucial social environment for young people but substance use researchers have largely overlooked potential influences operating at this level. This study explores associations between school-class and individual-level factors and cannabis use in Swedish youth.

Data and methods:

Data comprised four waves (2012–2015) of the Swedish Council for Information on Alcohol and Other Drugs’ (CAN) nationally representative school surveys among individuals in 9th and 11th grade. For the present analyses, we had data on totally 28,729 individuals from 2377 unique school classes. Multilevel logistic regressions predicted lifetime and 10+ times use of cannabis from both individual-level predictors and school-class-level measures derived from the individual-level variables.

Results:

There were individual-level associations between most predictor variables and cannabis use. An early debut of tobacco use and binge drinking as well as low cannabis related risk perceptions had strong associations with cannabis use. Conversely, several school-class-level variables had aggregate relationships with cannabis use, most notably the overall level of risk perceptions in the school class. Some of the school-class factors predicted cannabis use over and above the individual-level covariates, suggesting the presence of contextual effects. Surprisingly, while female gender was negatively related with cannabis use at the individual level, a higher proportion of females in the classroom increased the odds for lifetime cannabis use even after controlling for individual and other contextual-level covariates.

Conclusions:

Youth cannabis use is related to various factors at both the individual and school-class level in Sweden. Truancy and perceived risk related to cannabis use had contextual associations with cannabis use. The positive contextual association between a higher proportion of females in the classroom and lifetime use should be explored further.