Long-term effects of cannabis

Cannabis use is common in young people and the drug is widely perceived as being the least harmful of the numerous illicit substances available. There is reasonable evidence, however, that long-term use of cannabis is associated with adverse psychosocial outcomes, and accumulating evidence that cannabis use may have a causal association with onset of psychosis. The role of cannabis as a ‘gateway’ to use of other drugs such as heroin is considered. Other adverse associations with cannabis use include impairment in driving skills, of which a long-term consequence may be serious injury, and a possible association with subtle cognitive deficits in children exposed to cannabis prenatally.