Cannabis and Psychosis
European Psychiatry January 1, 2009 I.B. Crome
This contribution reviews UK research on substance misuse and mental illness over the past 20 years. Early work focused on alcohol and alcoholic hallucinosis, concluding that few cases developed into schizophrenia. More recent large epidemiological and clinical studies examine the relationship between cannabis use and later psychosis. The presentation cautions against asserting cannabis is necessarily causal, highlighting clinical and policy implications of misinterpreting evidence. It proposes revisiting alcohol-related psychotic illness with more sophisticated methods and suggests investigating other drugs associated with psychotic illness to find a common mechanism linking substance use and psychosis.