[Cannabis use and risk of psychosis, an etiological link?].

CANNABIS TO TREAT PSYCHOSIS: The nature of the link between cannabis use and psychosis remains to be clarified. Cross-sectional epidemiological studies have shown that individuals with psychosis use cannabis more often than other individuals in the general population. It has long been considered that this association was explained by the self-medication hypothesis, postulating that cannabis is used to self-medicate psychotic symptoms. This hypothesis has been recently challenged. PSYCHOTIC DISORDERS ENHANCED BY CANNABIS: Several prospective studies carried out in population-based samples, showed that cannabis exposure was associated with an increased risk of psychosis. A dose-response relationship was found between cannabis exposure and risk of psychosis, and this association was independent from potential confounding factors such as exposure to other drugs and pre-existence of psychotic symptoms. The brain mechanisms underlying the association have to be elucidated; they may implicate deregulation of cannabinoid and dopaminergic systems. A RISK FACTOR NOT TO BE NEGLECTED: Cannabis exposure may be a risk factor for psychotic disorders by interacting with a pre-existing vulnerability for these disorders. If further studies confirm that cannabis is a risk factor for psychosis, its impact on the population's mental health may not be negligible considering the growing number of adolescents exposed to this substance.