Reefer madness: Cannabinoid psychoses

Until recently, very few psychiatrists would have regarded cannabis as harmful to mental health, but that situation has changed dramatically. A number of large-scale epidemiological studies have clearly demonstrated that cannabis use is a risk factor for later schizophrenia and that the earlier the use starts the greater the risk. There has also been rapid progress in our knowledge of the endogenous cannabinoid system and renewed interest in the medicinal uses of cannabinoids.