Effect of Clozapine on Caudate Nucleus Volume in Relation to Symptoms of Schizophrenia

OBJECTIVE: Studies have found that caudate volume increased after treatment with typical antipsychotics in patients with schizophrenia but decreased after treatment was changed to clozapine. In the current study the authors examined whether this volume decrease was related to clinical improvement. METHOD: Twenty-eight patients with schizophrenia who had not responded to treatment with typical antipsychotics were included in the study; 22 completed the study. Caudate volume was assessed by using magnetic resonance imaging during treatment with typical antipsychotics and after 24 weeks and 52 weeks of clozapine treatment. Symptoms were assessed just before clozapine treatment and once a month thereafter. RESULTS: Clozapine treatment resulted in a significant reduction in left caudate volume in patients who responded to the drug but not in patients who did not respond to clozapine at 52 weeks of treatment. Overall, the degree of reduction in left caudate volume was significantly related to the extent of improvement in positive and general symptoms but not in negative symptoms. CONCLUSIONS: These findings suggest that the caudate nucleus plays a role in the positive and general symptoms of schizophrenia.