Instrumental Assessment of Bradykinesia: A Comparison Between Motor Tasks

Bradykinesia, a common symptom in psychiatry, is characterized by reduced movement speed and amplitude. Monitoring for bradykinesia is important, as it has been associated with reductions in quality of life and medication compliance. Subtle forms of bradykinesia have been associated with treatment response in antipsychotic-naive first episode patients. Therefore, accurate and reliable assessment is of clinical importance. Several mechanical and electronic instruments have been developed for this purpose. However, their content validity is limited. This study investigated which tasks, or combinations thereof, are most suitable for assessing bradykinesia instrumentally. Eleven motor tasks were assessed using inertial sensors. Their capability of distinguishing bradykinetic patients with schizophrenia (n = 6) from healthy controls (n = 5) was investigated. Seven tasks significantly discriminated patients from controls. The combination of tasks considered most feasible for the instrumental assessment of bradykinesia was the gait, pronation/supination, leg agility and flexion/extension of elbow tasks (effect size = 2.9).