Motor-Cognitive Dual-Task Cost and Associated Micro Lesions of Cerebellum and Brainstem in Multiple System Atrophy (Parkinsonian Type)

In multiple system atrophy with parkinsonian type (MSA-P), the dual-task cost and the underlying neurological mechanisms remain under-researched. We included 20 early-stage MSA-P patients and 10 matched healthy controls (HC). Using a video-based gait analysis machine, we explored gait characteristics under three conditions: single-task gait (STG), dual-task gait with backward counting (DTG-BC), and dual-task gait with spontaneous animal naming (DTG-SAN). Neuroimaging scans were collected to analyze the gray matter and white matter structures related to the dual-task cost in MSA-P. Our neuroimaging analysis focused on the infratentorial structures, as previous studies have indicated that these regions are closely related to dual-task cost. There were no differences in gait metrics between MSA-P and HC in STG. In the DTG-BC, patients with MSA-P exhibited a higher dual-task cost burden, as indicated by longer turning durations and shorter swing cycles compared to HC. MSA-P patients had decreased gray matter volume in the right culmen and increased radial diffusivity in the left declive compared to HC. Diffusion tensor imaging analysis showed that the higher dual-task cost of the right swing cycle in DTG-BC was related to the higher mean diffusivity of the left mesencephalic locomotor region (MLR). Additionally, a higher dual-task cost of turning duration in DTG-BC was related to increased axial diffusivity and radial diffusivity in the white matter of the bilateral culmen. Patients with MSA-P exhibited a higher dual-task burden compared to HC, and WM deficit in MLR and culmen were related to the disease's specific dual-task cost in MSA-P.