Clinical effectiveness of the Kampo medicine kamishoyosan for adjunctive treatment of tardive dyskinesia in patients with schizophrenia: A 16‐week open trial

Abstract

The purpose of the present study was to evaluate the clinical effectiveness of kamishoyosan for antipsychotic-induced tardive dyskinesia, and to investigate the relationship between tardive dyskinesia and serum brain-derived neurotrophic factor (BDNF) levels. Sixty-nine schizophrenia patients were enrolled; of these, 49 presented with tardive dyskinesia while the remaining 20 patients showed no tardive dyskinesia. The tardive dyskinesia group was treated for 16 weeks with kamishoyosan and assessed using the abnormal involuntary movement scale. The abnormal involuntary movement scale scores in the tardive dyskinesia group were evaluated at baseline and after 4, 8, and 16 weeks of treatment. The BDNF levels of all subjects were measured at baseline in order to compare differences in serum BDNF levels between the tardive dyskinesia group and the non-tardive dyskinesia group, and to correlate the severity of tardive dyskinesia and serum BDNF in the tardive dyskinesia group. A meaningful reduction in total abnormal involuntary movement scale scores was observed in the tardive dyskinesia group treated with kamishoyosan at 4, 8, and 16 weeks of treatment (P < 0.01). No significant differences in serum BDNF levels were detected between the tardive dyskinesia group and the non-tardive dyskinesia group at baseline. Furthermore, no significant correlation was seen between the severity of tardive dyskinesia and serum BDNF levels. The present study suggests that kamishoyosan might be a promising adjunctive treatment for antipsychotic-induced tardive dyskinesia.