Longitudinal associations of cannabis, depression, and anxiety in heterosexual and LGB adolescents.

Cannabis use is linked to symptoms of depression and anxiety, particularly among sexual minorities. This study examines the relationships between cannabis, and depression and anxiety symptoms at 13, 15, and 17 years using cross-lagged models in a predominantly White (n = 1,430; 92%) subsample of 1,548 participants from the Quebec Longitudinal study of Child Development. Multigroup analyses were conducted to examine the models according to sexual orientation. Demographic covariates were included as control variables, as well as alcohol, cigarette, and other drug use to examine cannabis specificity. The full sample revealed small bidirectional associations, which remained significant once control variables were included in the model: cannabis at 13 and 15 years predicted anxiety symptoms at 15 and 17 years respectively, and depression symptoms at 15 years predicted cannabis at 17 years. The initial association between cannabis at 13 years and depression symptoms at 15 years was accounted for by other drug use at 13 years. Substantial differences were found between heterosexual participants and sexual minorities: LGB participants presented a substantially larger positive association between depression symptoms at 15 years and cannabis at 17 years, as well as a negative association between anxiety symptoms at 15 years and cannabis at 17 years. Both of these relationships remained significant when accounting for control variables. These results suggest that the relationships between cannabis, and depression and anxiety symptoms are bidirectional across adolescence, albeit small. Sexual minorities present particularly large associations that may represent self-medication efforts for depressive symptoms between 15 and 17 years. (PsycInfo Database Record (c) 2021 APA, all rights reserved).