Cannabis and psychosis revisited.

The association between cannabinoids and psychosis has been known for almost a thousand years, but it is still speculated whether cannabis use may be a contributory cause of psychosis, that is, whether it may precipitate schizophrenia in those at risk. In this paper, we will briefly present the data from individual longitudinal studies in the field, together with the factors that are considered important for the association of cannabis abuse and occurrence of schizophrenia and prevention opportunities in the target population. The reviewed studies clearly suggest that cannabis abuse predicts an increased risk for schizophrenia, particularly in young adults. They underline both the need to create adequate prevention measures and consequently avoid the occurrence of the disease in the young at risk. Particular attention should be additionally devoted toward encouraging the young presenting with psychotic symptoms to stop or, at the very least, reduce the frequency of cannabis abuse. The issues are undoubtedly to be addressed by the health care system in general.