Cannabis psychoses in south Sweden.

Over one year, eleven patients hospitalized with psychosis linked to cannabis abuse were studied, excluding those with pre-existing psychosis or mixed substance use. Patients fell into acute, subacute, and chronic groups. All showed similar symptoms: a mix of affective and schizophrenia-like features, confusion, and pronounced aggressiveness. The illness typically resolved on its own without lasting effects, and there was almost no family history of severe mental illness. The symptoms closely resembled cycloid psychosis, and a possible connection between the two is discussed. Despite widespread cannabis use, psychosis is a rare complication, but in unclear psychotic states, actively searching for cannabis psychosis is recommended.

Study at a glance

Abstract

Eleven patients with a psychosis in connection with cannabis abuse admitted to two mental hospitals during 1 year were examined. Patients with a pre-existent psychosis or a mixed abuse were excluded. The patients were divided into three groups: acute, subacute and chronic. The features of the disease were essentially similar in all patients, with a mixture of affective and schizophrenia-like symptoms, confusion and a pronounced aggressiveness. The course as a rule was self-limiting leaving no residual symptoms. There was almost no heredity of severe mental disease. The symptoms were very similar to those seen in cycloid psychosis, and a possible relationship between the two diseases is discussed. As regards the widespread abuse of cannabis we conclude that psychosis is a rare complication but that in unclear psychotic states it is recommended to actively search for a cannabis psychosis.