Atypical Dual-Task Cost and Reduced Attentional Neural Modulation in Parkinson’s Disease With Freezing of Gait

BACKGROUND: Dual-task walking poses substantial challenges for individuals with Parkinson's disease (PD), particularly those with freezing of gait (FOG), as dual-task interference increases fall risk and limits functional mobility. OBJECTIVE: To investigate dual-task interference at both the behavioral and neural levels in PD individuals with FOG (PDFOG+) and those without FOG (PDFOG-) during dual-task walking involving a demanding manual task. METHODS: Seventeen PDFOG- and 17 PDFOG+ participated in this study. Gait performance, manual-task performance, and scalp electroencephalograph (EEG) were recorded in single-task condition and dual-task walking while performing a high attentional-load manual task (an interlocking ring task). The primary behavioral outcomes were dual-task costs (DTC) of gait velocity and ring performance, representing locomotor interference and manual-task interference, respectively. The primary neural outcomes focused on theta-band EEG measures, including regional theta power and inter-regional theta connectivity, given their established role in attentional control during dual-task walking in PDFOG+. RESULTS: Compared with PDFOG-, PDFOG+ exhibited significantly less DTC of gait velocity and greater DTC of ring performance. At the neural level, PDFOG+ demonstrated attenuated task-dependent modulations of increased theta-band power and decreased theta-band connectivity relative to PDFOG-. CONCLUSIONS: PDFOG+ exhibited an atypical pattern of dual-task interference characterized by preserved gait velocity at the expense of concurrent manual-task performance, together with diminished theta-band attentional modulation. These findings suggest limited flexibility in attentional resource allocation in PDFOG+ and highlight theta-band neural dynamics as a key mechanism underlying maladaptive task-task regulation during walking. TRIAL REGISTRATION: National Taiwan University Hospital Research Ethics Committee: No. NCT03298503.