Cannabis use among Swedish men in adolescence and the risk of adverse life course outcomes: results from a 20 year-follow-up study (2015)

Aims: To examine associations between cannabis use in adolescence (at age 18) and unemployment and social welfare assistance in adulthood (at age 40) among Swedish men.
Design: Longitudinal cohort study.
Setting and Participants: A total of 49 321 Swedish men born in 1949-51, who were conscripted to compulsory military service at 18-20 years of age.
Measurements: All men answered two detailed questionnaires at conscription and were subject to examinations of physical aptitude psychological functioning and medical status. By follow-up in national databases, information on unemployment and social welfare assistance was obtained.
Findings: Individuals who used cannabis at high levels in adolescence had increased risk of future unemployment and of receiving social welfare assistance. Adjusted for all confounders (social background, psychological functioning, health behaviours, educational level, psychiatric diagnoses), an increased relative risk (RR) of unemployment remained in the group reporting cannabis use > 50 times [RR = 1.26, 95% confidence interval (CI) = 1.04-1.53] only. For social welfare assistance, RR in the group reporting cannabis use 1-10 times was 1.15 (95% CI = 1.06-1.26), RR for 11-50 times was 1.21 (95% CI = 1.04-1.42) and RR for > 50 times was 1.38 (95% CI = 1.19-1.62).
Conclusions: Heavy cannabis use among Swedish men in late adolescence appears to be associated with unemployment and being in need of social welfare assistance in adulthood. These associations are not explained fully by other health-related, social or behavioural problems.