Dual-task interference during hand dexterity is a predictor for activities of daily living performance in Parkinson's disease.

Introduction: Dual-task interference (DTI) leads to impairment of hand dexterity in Parkinson's disease (PD). The performance of activities of daily living (ADL) is negatively affected by dexterity in PD. However, the contribution of DTI to dexterity-related ADL disability remains unclear. This cross-sectional study aimed to investigate the contribution of DTI to ADL performance as well as other factors affecting dexterity.

Methods: One-hundred and eight patients with PD were assessed using the ADL-related dexterity questionnaire-24 to measure dexterity-related ADL performance. Performance in single and dual task conditions was measured with the 9-hole peg test. Disease severity, cardinal symptoms and grip strength were assessed using Hoehn&Yahr, a modified version of the Unified Parkinson Disease Rating Scale, Part-III, and a hand dynamometer. The age and cognitive status were control variables.

Results: Multiple regression analysis revealed that disease severity explained 8.5% of the variance in dexterity-related ADL (p = 0.002). The DTI in the dominant hand was the strongest predictor of ADL performance (R change = 0.44, p < 0.001), but DTI in the non-dominant hand did not contribute. When cardinal symptoms were added to the model, bradykinesia contributed to ADL difficulty (R change = 0.072, p < 0.001), while tremor and rigidity were not significant in any model. This model accounted for 59.2% of the variance in ADL difficulties in total.

Conclusion: The study demonstrated that disease severity, bradykinesia and DTI in the dominant hand contributed to ADL difficulties in patients with PD, and DTI in the dominant hand is the strongest predictor of ADL performance in PD.