Dual-task gait and gait-cognition coupling in patients with Parkinson's disease versus healthy older adults: moderation by cognitive status.

BACKGROUND: Gait impairment and cognitive decline frequently co-occur in Parkinson's disease (PD), yet how cognitive status modulates dual-task gait-cognition relationships remains poorly characterized. OBJECTIVE: To compare spatiotemporal gait parameters and dual-task costs (DTCs) between drug-naïve PD and healthy older adults (HO), and to examine how cognitive status modulates gait-cognition associations within PD. METHODS: One hundred twenty-four participants (65 PD, 59 HO) were prospectively enrolled. PD patients were subclassified into cognitively normal (PDCN, n = 38) and mild cognitive impairment (PDMCI, n = 27) groups. Gait was assessed using the GAITRite system under four conditions: preferred speed, serial sevens subtraction, cell phone use, and backward walking. Partial Spearman correlations and moderation analyses were conducted. RESULTS: PD-related gait impairments were more pronounced under dual-task conditions, with cell phone use yielding the greatest between-group differences in spatiotemporal parameters and DTCs. Gait-cognition associations in the total PD group were most consistently observed during cell phone use, involving executive, language, and attention domains. DTCs were specifically correlated with executive and language domains. Subgroup analyses revealed distinct cognitive-motor profiles: PDCN showed a paradoxical pattern in which better visuospatial function was associated with greater gait variability, while PDMCI exhibited broader positive correlations between multiple cognitive domains and gait stability. Moderation analyses confirmed these patterns were statistically distinct. CONCLUSION: Dual-task gait assessment using a cell phone paradigm may effectively characterizes cognitive-motor decline in early drug-naïve PD. Cognitive status qualitatively modulates gait-cognition coupling, with domain-specific patterns differing between PDCN and PDMCI, with implications for targeted monitoring and intervention.