Cannabis and mental illness
David Castle
Abstract
Abstract Cannabis sativa is a drug of potential dependence, and its users are also at increased risk of using other drugs. It has anxiolytic and sedative properties, but in some individuals, it can precipitate panic. There is an association between cannabis consumption and depression, but cohort studies suggest the association is mostly reverse causality. Cannabis can produce psychotic phenomena, notably in individuals with psychosis proneness. It appears to ‘bring forward’ the onset of schizophrenia, and it may act as a cumulative causal factor for schizophrenia. Acute cognitive effects of cannabis are well described, as is an amotivational syndrome with heavy prolonged use. Some evidence suggests enduring neurocognitive effects in heavy users. There is particular concern regarding use of high-potency cannabis in youth, as it appears that its effects on cognition and its potential contribution to depressive and psychotic disorders are particularly marked during this developmental phase.