The commitment to dual-task walking is not linear with the progression of Parkinson's disease

Abstract

Background: Parkinson’s disease (PD) impairs gait automaticity, particularly under dual-task (DT) conditions. Although DT gait is widely used as a marker of cognitive-motor interference in PD, it remains unclear whether DT costs are associated with the clinical progression of the disease. Objective: To investigate whether motor and cognitive DT costs during gait differ between early and intermediate stages of PD. Methods: A cross-sectional observational study was conducted according to the STROBE guidelines and included 49 participants classified in Hoehn & Yahr (H&Y) stages 1 (n=18), 2 (n=20), and 3 (n=11). Inclusion criteria were: (1) diagnosis of PD; (2) use of dopaminergic medication; and (3) ability to walk short distances independently without assistive devices. Exclusion criteria were: (1) other neurological conditions; (2) uncorrected visual or hearing impairments; and (3) orthopedic, cardiac, or respiratory conditions that could interfere with the study procedures. All participants were assessed in a single session by trained physiotherapists during the ON medication state. Depressive symptoms were assessed using the Geriatric Depression Scale (GDS); balance responses were evaluated using the Balance Evaluation Systems Test (BESTest); PD severity and clinical progression were assessed using sections II and III of the Unified Parkinson’s Disease Rating Scale (UPDRS); and global cognitive function was assessed using the Montreal Cognitive Assessment (MoCA). Gait was assessed using the GAITRite® system to capture spatiotemporal gait parameters under three conditions: (1) single motor task (walking only); (2) single cognitive task (standing quietly while generating as many words as possible beginning with a predetermined letter); and (3) DT (combination of the motor and cognitive tasks). Statistical analysis employed nonparametric tests to compare DT costs across H&Y stages using the Kruskal-Wallis test, with correction for multiple comparisons using the Benjamini-Hochberg method. Results: No statistically significant differences were observed in motor or cognitive DT costs of gait across disease stages, even after correction for multiple comparisons. Substantial interindividual variability was observed across all stages, and regression analyses did not identify significant associations between DT costs and the clinical variables assessed. Conclusion: The findings indicate that deficits in gait automaticity under DT conditions do not progress linearly between early and intermediate stages of PD, suggesting that gait difficulties emerge early in the disease and highlighting the importance of their identification and management from the initial stages.