Spontaneous dyskinesia in first-episode psychosis in a Southeast Asian population.

Spontaneous dyskinesia in first-episode psychosis was described previously with varying incidence rates ranging from zero to 53%. Dyskinesia was also found to be more common in siblings of patients with both schizophrenia and dyskinesia. This condition was linked with structural brain abnormalities and posited to be another subtype of schizophrenia with striatal pathology. Whether there are ethnic variations in the rates of spontaneous dyskinesia is unknown because of the paucity of studies in this area. This study aims to establish the rates of spontaneous dyskinesia in a Southeast Asian population of drug-naive patients experiencing their first psychotic episode and to examine the clinical correlates. A total of 908 patients were examined, of which, 76.1% were Chinese; 15.4%, Malays; 6.2%, Indians; and 2.3%, from other minor ethnic groups. Schizophrenia was diagnosed in 48.9% of the population. There were 3 patients of Chinese descent who had "minimal" or "mild" dyskinetic movements when rated with the Abnormal Involuntary Movement Scale, but none fulfilled the Schooler and Kane criteria for spontaneous dyskinesia. Their dyskinetic movements resolved when reassessed 3 and 6 months after treatment with antipsychotic medications. Of the 3 patients, 2 were treatment resistant and subsequently treated with clozapine. This is the largest study to date examining the prevalence of spontaneous dyskinesia. We hypothesize that there is an ethnically based difference in the rates of spontaneous dyskinesia that could reflect underlying genetic variations. Patients with dyskinetic movements at baseline could have a more treatment refractory course of illness.