Effect of substance misuse in early psychosis.

BACKGROUND: Studies examining the temporal relationship between substance use and the onset of psychotic symptoms in schizophrenia are inconclusive. METHOD: Three groups of out-patients with schizophrenia were compared on onset of illness, symptoms and quality of life. Fifty-one subjects had no past or present history of substance misuse, 29 subjects had a history of past substance misuse occurring around the onset of their illness, and 33 subjects were currently misusing substances. RESULTS: Current substance misusers had poorer quality of life scores and less negative symptoms than the non-users. Those who had a past history of substance misuse had a significantly earlier age of onset than those with no substance use. CONCLUSIONS: Attention should be paid to substance misuse present at the first episode. Treatment for schizophrenia should begin even though a diagnosis of drug-induced psychosis cannot be ruled out.