Quantification of motor abnormalities with instrumental tasks among adolescents with first-episode schizophrenia and depressive disorders

Motor abnormalities, including extrapyramidal symptoms (EPS) induced by antipsychotic medication, are of prognostic value for clinical outcomes for individuals with schizophrenia. Instrumental methods for quantitative assessment of motor abnormalities in schizophrenia are still underdeveloped, with current assessments relying on observations and subjective scales. This study aimed to develop easy-to-implement and reliable instrumental methods to measure motor abnormalities in youth with schizophrenia who started their medication. Three motor tasks, including upper-limb weight holding, quiet standing, and level-ground walking, were instrumentally evaluated to capture essential aspects of motor abnormalities, such as akathisia, dyskinesia, and Parkinsonism. We recruited adolescents with schizophrenia (SZ group), an age-matched healthy control group (NC group), and a group of age-matched patients with depression (DP group). The SZ and DP groups were both newly exposed to antipsychotic drugs, and their comparisons were to determine if motor abnormalities are schizophrenia-specific. SZ patients indeed performed significantly worse with more upper-limb tremors and walking abnormalities. While no group difference was found in standing stability, the SZ group's postural stability measures correlated with clinic scale scores. With motor features from these instrumental methods, a simple linear classifier classified the three participant groups with decent accuracy. Our findings suggest that instrumental motor tasks hold promise for sensitive detection and differentiation of motor abnormalities in adolescents with newly diagnosed schizophrenia and antipsychotic intake. Further developments of these instrumental methods are promising for improving motor assessment and treatment outcomes in clinical practice.