Age at onset of schizophrenia and neuroleptic dosage

Background: Lower age at onset of schizophrenia has been traditionally associated with poorer response to treatment and less favourable prognosis. The aim of the study was to find out whether age at onset of schizophrenia is related to the dosage of typical neuroleptics in outpatients. Method: Age at onset was defined as age at first seeking of psychiatric help. Demographic, social and disease-related characteristics were studied in a group of 200 stable outpatients with schizophrenia (100 males and 100 females). Psychopathological symptoms were assessed with the Krawiecka Scale. Neuroleptic dosage was converted to milligrams of chlorpromazine equivalents and logarithmically transformed to obtain normal distribution. Results: Onset of schizophrenia occurred earlier in males than in females. The average dosage was 251.7 (SD 303.9) mg chlorpromazine equivalents. In a multivariate linear regression model, lower age at onset and higher sum of symptoms were related to the drug dosage. Conclusion: The results confirm the findings of other authors that patients with lower age at onset are less responsive to typical neuroleptics. Some of the patients with early onset would be more appropriately treated with atypical neuroleptics, which may have better therapeutic efficacy. Accepted: 3 September 1999