Differential effect of low and conventional doses of fluphenazine on schizophrenic outpatients with good or poor information-processing abilities.

Thirty-six stabilized schizophrenic outpatients were randomly assigned to receive either 5 or 25 mg of fluphenazine decanoate biweekly and were followed up for two years. The best and worst outcomes were found in groups with good or poor information-processing abilities (as measured by a partial-report span-of-apprehension task) given the same 25-mg dose of fluphenazine decanoate. The 86% two-year survival rate of the patients with poor span performance was considerably better, while the 44% one-year and the 21% two-year survival rates of patients with good span performance were considerably lower than previously reported survival rates for schizophrenic patients receiving a conventional dose of fluphenazine. The significant correlations in a patient's span performance for periods up to one year were consistent with the hypothesis that this task taps processes associated with vulnerability to schizophrenic disorder.