Cognition and dual-task performance in older adults with Parkinson’s and Alzheimer’s disease

BACKGROUND Patients with neurodegenerative diseases usually experience significant functional deficits. Older adults with Parkinson's disease (PD) and Alzheimer's disease (AD) may suffer from both motor and cognitive impairments, making them especially vulnerable to poor dual-task performance. OBJECTIVE To analyze the dual-task cost of walking in subjects with PD and AD exposed to motor and cognitive distracters. METHODS A cross-sectional study was conducted involving 126 older adults comprising three groups: PD (n=43), AD (n=38), and control (n=45). The subjects were evaluated using the Timed Up and Go (TUG) test administered with motor and cognitive distracters. Mixed-design analysis of variance (ANOVA) with cognition as a covariant factor was used to test the possible main effects of dual-task on motion. A 5% threshold for significance was set, with a 95% confidence interval (CI). The partial eta square (n(2)p) analysis was included to estimate the magnitude of effect. RESULTS Examining the effects for dual-task, ANOVA revealed the main effect for group×task interactions (F=13.09; P=0.001; n(2)p =0.178), for task (F=8.186; P=0.001; n(2)p =0.063) but not for group (F=2.954; P=0.056; n(2)p =0.047). Cognition applied as a covariant factor indicated interference on dual-tasks (F=30.43; P=0.001; n(2)p =0.201). CONCLUSION The findings of this study suggest that dual-task interference is a particularly noticeable problem in PD and AD, affecting subjects' ability to appropriately adapt to environmental challenges.