Characteristics of responders to interventions for Parkinson disease: a scoping systematic review

The purpose of this review is to identify the characteristics of responders in interventions targeting motor function for individuals with Parkinson disease. The primary search included, ‘Parkinson’ + ‘responder.’ A second, broader, search further included ‘response’ + ‘responsiveness’ + ‘responsive.’ Records were sorted by intervention: neuromodulation, pharmaceutical, physical, and placebo. Thirteen studies were identified in the primary and 19 studies in the secondary search, culminating in 120 characteristics. For neuromodulation interventions, responders were younger at onset, more responsive to levodopa, and had more difficulties with activities of daily living. Responders to pharmaceuticals were younger at diagnosis. Physical intervention responders had worse balance, less balance confidence, and worse cognition. No relevant characteristics were identified for placebo interventions. Although there are clear limitations and gaps in the literature, responder analyses represent an important step toward more personalized treatments for the motor symptoms of Parkinson disease.