Substance use in a population-based clinic sample of people with first-episode psychosis.

BACKGROUND: Substance use is implicated in the cause and course of psychosis.

AIMS: To characterise substance and alcohol use in an epidemiologically representative treatment sample of people experiencing a first psychotic episode in south Cambridgeshire.

METHOD: Current and lifetime substance use was recorded for 123 consecutive referrals to a specialist early intervention service. Substance use was compared with general population prevalence estimates from the British Crime Survey.

RESULTS: Substance use among people with first-episode psychosis was twice that of the general population and was more common in men than women. Cannabis abuse was reported in 51% of patients (n=62) and alcohol abuse in 43% (n=53). More than half (n=68, 55%) had used Class A drugs, and 38% (n=43) reported polysubstance abuse. Age at first use of cannabis, cocaine, ecstasy and amphetamine was significantly associated with age at first psychotic symptom.

CONCLUSIONS: Substance misuse is present in the majority of people with first-episode psychosis and has major implications for management. The association between age at first substance use and first psychotic symptoms has public health implications.