Cannabis and crime: findings from a longitudinal study.

AIM: To examine the association between cannabis use during adolescence and young adulthood, and subsequent criminal charges.
METHODS: Data were obtained from the Young in Norway Longitudinal Study. A population-based sample (n = 1353) was followed from 13 to 27 years of age. Data were gathered on cannabis use, alcohol consumption and alcohol problems, and use of other illegal substances such as amphetamines, cocaine and opiates. In addition, extensive information on socio-demographic, family and personal factors was collected. This data set was linked to individual-level information from official Norwegian crime statistics.
FINDINGS: We found robust associations between cannabis use and later registered criminal charges, both in adolescence and in young adulthood. These associations were adjusted for a range of confounding factors, such as family socio-economic background, parental support and monitoring, educational achievement and career, previous criminal charges, conduct problems and history of cohabitation and marriage. In separate models, we controlled for alcohol measures and for use of other illegal substances. After adjustment, we still found strong associations between cannabis use and later criminal charges. However, when eliminating all types of drug-specific charges from our models, we no longer observed any significant association with cannabis use.
CONCLUSIONS: The study suggests that cannabis use in adolescence and early adulthood may be associated with subsequent involvement in criminal activity. However, the bulk of this involvement seems to be related to various types of drug-specific crime. Thus, the association seems to rest on the fact that use, possession and distribution of drugs such as cannabis is illegal. The study strengthens concerns about the laws relating to the use, possession and distribution of cannabis.