Smoking Mostly Alone as a Risk Factor for Cannabis Use Disorders and Depressive Symptoms.

The empirically grounded etiological models of cannabis use already include a vast range of psychological factors (within an individual), paving the ground for individualized prevention and intervention programs. However, the interpersonal (among individuals) and relational variables influencing the emergence of excessive cannabis use are less understood. Particularly, the impact of consumption context (i.e., smoking alone or with others) on cannabis use intensity in youth remains to be clarified. We evaluated how smoking mostly alone modulates cannabis use disorders (CUD) and depressive symptoms in college students. A sample of 854 individuals from France (568 women, 286 men) who used cannabis in the last 6 months completed self-report questionnaires evaluating cannabis consumption, CUD symptoms, and depressive symptoms. Mostly alone users presented higher current use frequency as well as increased CUD and depressive symptoms compared to mostly social users. Smoking mostly alone remained positively correlated with CUD and depressive symptoms, even when controlling for current use frequency. The association between smoking mostly alone and depressive symptoms was significant before adjustment for symptoms of CUD. The loss of significance of this association after control reflected the mediating effects of symptoms of CUD on the relationship between smoking mostly alone and depressive symptoms. These results suggest that smoking mostly alone constitutes a risk factor for uncontrolled cannabis use and promote the relationship between cannabis use and depressive disorders, potentially through loneliness and social isolation. Longitudinal studies are required to identify the causal mechanisms underlying the links between smoking mostly alone, cannabis use and psychopathological disorders.