Prevalence and characteristics of subjective akathisia, objective akathisia, and mixed akathisia in chronic schizophrenic subjects.

Akathisia is a complex syndrome that is characterized by subjective inner restlessness and objective motor manifestations, and it can be classified into several subtypes. The purpose of this study was to examine the prevalence of subjective akathisia, objective akathisia, and mixed akathisia, and to evaluate their relationships with other drug-induced movement disorders, in chronic schizophrenic subjects treated with antipsychotics. One hundred and forty-two in-patients were assessed for akathisia, drug-induced parkinsonism, and tardive dyskinesia. The subtypes of akathisia were specified according to the Barnes Akathisia Rating Scale. Drug-induced parkinsonism and tardive dyskinesia were assessed using the Simpson-Angus Scale and the Abnormal Involuntary Movement Scale, respectively. The prevalence of subjective, objective, and mixed akathisia was 11.3%, 6.3%, and 16.9%, respectively. Regarding concurrence rates of akathisia subtypes and other extrapyramidal syndromes, the comorbidity rates of mixed akathisia with parkinsonism and tardive dyskinesia were higher. In conclusion, the present study presented the prevalence of subjective, objective, and mixed akathisia among hospitalized schizophrenic subjects. Mixed akathisia showed an association with parkinsonism and tardive dyskinesia, suggesting a common vulnerability involved in these drug-induced movement disorders. Further studies are required to elucidate more detailed clinical characteristics of each subtype of akathisia.