The factor structure of extrapyramidal symptoms evaluated using the DIEPSS in patients with schizophrenia: results from the 2016 REAP AP-4 study

Abstract

\n Drug-induced extrapyramidal syndrome (EPS) remains a major problem in clinical psychiatry. This study aimed to examine the factor structure of drug-induced extrapyramidal symptoms observed in patients with schizophrenia and assessed using the Drug-Induced Extrapyramidal Symptoms Scale (DIEPSS). The participants were 1,478 patients with a diagnosis of schizophrenia whose EPS was assessed using the DIEPSS in India, Indonesia, Japan, Malaysia, and Taiwan in the 2016 REAP AP-4 study. The records of the participants were randomly divided into two subgroups: the first for exploratory factor analysis of the eight DIEPSS items and the second for confirmatory factor analysis. The factor analysis identified three factors: F1 (sialorrhea, akathisia, dystonia, and dyskinesia), F2 (gait and bradykinesia), and F3 (muscle rigidity and tremor). The present results suggest that the eight individual items of the DIEPSS could be composed of three different mechanisms: central dopaminergic mechanisms with the pathophysiology other than acute parkinsonism (F1), acute parkinsonism observed during action (F2), and acute parkinsonism observed at rest (F3).