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Early course of schizophrenia in a representative Dutch incidence cohort.

Selten JP, Veen ND, Hoek HW, Laan W, Schols D, van der Tweel I, Feller W, Kahn RS

Rudolf Magnus Institute of Neuroscience, Department of Psychiatry, University Medical Center Utrecht, Utrecht, the Netherlands. J.P.Selten@umcutrecht.nl

PURPOSE: To describe the early course of psychotic disorders in general and to examine whether certain variables can predict the early course of schizophrenic disorders (DSM-IV: schizophrenia, schizophreniform or schizoaffective disorder). SUBJECTS AND METHOD: Follow-up and re-diagnosis of a highly representative Dutch incidence cohort (N=181), thirty months after first contact with a physician for a psychotic disorder. Poor course was defined as a continuous psychotic illness or a score of less than 39 on the Global Assessment of Functioning scale. RESULTS: The follow-up rate was 92%. 125 Subjects were diagnosed with a schizophrenic disorder. Poor course was present in 70 of these subjects (56%). Univariable analysis showed that male sex, heavy cannabis use during the follow-up period (sometimes or often more than one joint a day) and long duration of dysfunctioning before psychosis onset (>1 month) were predictors of poor course, while age at onset, ethnicity, socioeconomic status and duration of untreated psychosis (trend, p=0.08) were not. The effect of cannabis was confounded by sex. Multivariable analysis showed that male sex was the sole significant and independent predictor of poor course and explained 13% of the variation. The odds ratio for males, adjusted for duration of pre-psychotic dysfunctioning and cannabis use during the follow-up period, was 3.0 (95% CI, 1.0-8.9). STRENGTHS AND LIMITATIONS: This is the first study to examine the influence of cannabis in an epidemiological, highly representative sample. A limitation was the sample size. CONCLUSION: Male sex is an independent risk factor for an unfavorable early course in schizophrenia.

Published 20 November 2007 in Schizophr Res, 97(1): 79-87.
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