IMPORTANCE Cannabis is the most commonly used drug of abuse by adolescents in the world. While the impact of adolescent cannabis use on the development of psychosis has been investigated in depth, little is known about the impact of cannabis use on mood and suicidality in young adulthood.OBJECTIVE To provide a summary estimate of the extent to which cannabis use during adolescence is associated with the risk of developing subsequent major depression, anxiety, and suicidal behavior.DATA SOURCES Medline, Embase, CINAHL, PsycInfo, and Proquest Dissertations and Theses were searched from inception to January 2017.STUDY SELECTION Longitudinal and prospective studies, assessing cannabis use in adolescents younger than 18 years (at least 1 assessment point) and then ascertaining development of depression in young adulthood (age 18 to 32 years) were selected, and odds ratios (OR) adjusted for the presence of baseline depression and/or anxiety and/or suicidality were extracted. DATA EXTRACTION AND SYNTHESIS Study quality was assessed using the Research TriangleInstitute item bank on risk of bias and precision of observational studies. Two reviewers conducted all review stages independently. Selected data were pooled using random-effects meta-analysis. MAIN OUTCOMES AND MEASURESThe studies assessing cannabis use and depression at different points from adolescence to young adulthood and reporting the corresponding OR were included. In the studies selected, depression was diagnosed according to the third or fourth editions of Diagnostic and Statistical Manual of Mental Disorders or by using scales with predetermined cutoff points. RESULTSAfter screening 3142 articles, 269 articles were selected for full-text review, 35 were selected for further review, and 11 studies comprising 23 317 individuals were included in the quantitative analysis. The OR of developing depression for cannabis users in young adulthood compared with nonusers was 1.37 (95% CI, 1.16-1.62; I 2 = 0%). The pooled OR for anxiety was not statistically significant: 1.18 (95% CI, 0.84-1.67; I 2 = 42%). The pooled OR for suicidal ideation was 1.50 (95% CI, 1.11-2.03; I 2 = 0%), and for suicidal attempt was 3.46 (95% CI, 1.53-7.84, I 2 = 61.3%). CONCLUSIONS AND RELEVANCEAlthough individual-level risk remains moderate to low and results from this study should be confirmed in future adequately powered prospective studies, the high prevalence of adolescents consuming cannabis generates a large number of young people who could develop depression and suicidality attributable to cannabis. This is an important public health problem and concern, which should be properly addressed by health care policy.

Background: Alcohol use-related problems and depressive symptoms are clearly associated with each other, but results regarding the nature of this association have been inconsistent. In addition, the possible moderating effects of age and gender have not been comprehensively examined. The goals of this study were to clarify: (i) how depressive symptoms affect the levels and trajectory of alcohol use-related problems, (ii) how alcohol use-related problems affect the levels and trajectory of depressive symptoms, and (iii) whether there are differences in these associations at different points in development or between males and females.Methods: Participants for this study were drawn from the National Longitudinal Study of Adolescent Health (AddHealth) data set, a community-based sample of 20,728 adolescents followed from adolescence through early adulthood. Multilevel models were used to assess how each problem affected the level and rate of change in the other problem over time; gender was considered as a possible moderator of these associations.Results: The results indicated that alcohol use-related problems and depressive symptoms had reciprocal, positive associations with each other during the period from early adolescence through early adulthood; however, these effects differed somewhat by gender and age. High levels of depressive symptoms were associated with higher initial levels of alcohol problems (particularly among females), as well as faster increases in alcohol problems over time among males. High levels of alcohol problems were associated with higher initial levels of depressive symptoms (particularly among females), as well as less curvature in the slope of depressive symptoms so that although there was a large difference between people with high and low depressive symptoms in early adolescence, by early adulthood the difference was smaller (particularly among females).Conclusions: These results highlight the importance of examining gender and age in studies on the associations between affective disorders and substance use disorders.

The implications of these findings for the complex relationship between parental diagnoses, child diagnoses, and parent-child conflict are discussed.

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Using a prospective cohort design, the authors examined in this study whether childhood victimization increases the risk for illicit drug use and related problems in middle adulthood. Court-documented cases of childhood physical and sexual abuse and neglect and matched controls (N = 892) were first assessed as young adults (mean age = 29 years) during 1989-1995 and again in middle adulthood (mean age = 40 years) during 2000-2002. In middle adulthood, abused and neglected individuals were about 1.5 times more likely than controls to report using any illicit drug (in particular, marijuana) during the past year and reported use of a greater number of illicit drugs and more substance-use-related problems compared with controls. The current results reveal the long-term impact of childhood victimization on drug use in middle adulthood. These new results reinforce the need for targeted interventions with abused and neglected children, adolescents, and adults, and particularly for women.