The effect of clozapine on caudate nucleus volume in schizophrenic patients previously treated with typical antipsychotics

Typical antipsychotics have been reported to enlarge the caudate nucleus in schizophrenic patients. The atypical antipsychotic, clozapine, is associat ed with a decrease in caudate size in patients previously treated with typi cal antipsychotics. The present study investigates whether a change in caud ate volume after switching from treatment with typical antipsychotics to tr eatment with clozapine is related to improvement in symptoms or tardive dys kinesia (TD). Twenty-six schizophrenic patients participated in this open s tudy. Caudate nucleus volume and TD were assessed before discontinuing typi cal antipsychotics and after 24 weeks of treatment with clozapine. After di scontinuing typical antipsychotics, symptoms were assessed in a 3 days drug -free period and subsequently once a month. Treatment with clozapine result ed in a decrease in caudate volume, improvement in symptoms and amelioratio n of TD. However, no difference in caudate volume changes was found between responders and non-responders to clozapine and no correlations were found between caudate volume changes and reduction of TD. In conclusion, this stu dy replicates earlier findings that colzapine decreases caudate volume in p atients previously treated with typical antipsychotics and suggests that th is effect is unrelated to treatment response or to amelioration of TD. (C) 2000 American College of Neuropsychopharmacology. Published by Elsevier Sci ence Inc.