[Cannabis use and antisocial behaviors in high-school students]

The aim of the study was to evaluate the contribution of cannabis to the prediction of delinquent behaviors.

Participants were 312 high-school students who completed self-report questionnaires measuring antisocial behaviors, the frequency of cannabis and alcohol use, psychopathic traits using the Youth Psychopathic traits Inventory, borderline traits, depressive symptoms, socio-economic status, life events, attachment to parents, and low academic achievement. Hierarchical multiple regression analyses were conducted to investigate the contribution of cannabis use and potential confounding variables to antisocial behaviors.

Boys reported a greater number of delinquent behaviors than girls (10.2±9.2 vs. 5.4±5.3, t=9.2, P<0.001). Thirty-seven percent of boys and 24 % of girls reported having used cannabis at least once during the last six months (P<0.001). Among cannabis users, boys reported a greater frequency of use than girls: average use for boys was 2-3 times per month whereas average use for girls was once a month (3.4±2.3 vs. 2.6±2, t=2.9, P=0.004). Cannabis users reported a greater number of antisocial behaviors than non-users (13.2±9.9 vs. 6.1±6.3, t=13.6, P<0.001). Multiple regression analyses showed that cannabis use was a significant independent predictor of antisocial behaviors in both gender (β=.35, P<.001 in boys, β=.29, P<.001 in girls) after adjustment for alcohol use, psychopathological and sociofamilial variables.

The unique and independent association between frequency of cannabis use and antisocial behaviors does not indicate the causal direction of the relationship. It may be that cannabis use induces antisocial behaviors by enhancing impulsivity or irritability or by the need for money to buy cannabis. Conversely, antisocial behaviors may lead to cannabis use either through becoming used to transgressions or through the influence of delinquent peers using cannabis. This link is probably bidirectional, cannabis use and antisocial behaviors influencing mutually in a negative interactive spiral. This association suggests that these two problems are to be jointly approached when treating adolescents using cannabis or having antisocial behaviors.