Association of Physical Exercise With Structural Brain Changes and Cognitive Decline in Patients With Early Parkinson Disease

Accumulating evidence suggests that physical activity is associated with a better clinical and cognitive course in Parkinson disease (PD), yet whether these effects are subserved by structural brain alterations are largely unexplored. The aim of this study was to investigate whether regular physical activity associates with a reduced longitudinal rate of neurodegeneration and slower cognitive decline in PD. In this longitudinal, observational cohort study, we used data from the Parkinson's Progression Markers Initiative. We included patients with early PD who had serial assessments of regular physical activity, measured using the Physical Activity Scale for the Elderly, along with serial MRI scans from at least 2 time points over 4 years of follow-up. Regional cortical thickness and subcortical volumes were calculated using established procedures. We used multivariate linear mixed-effects models to analyze the effect of regular physical activity on the progression of MRI parameters over time. We further used mediation models with nonparametric bootstrap to test mediation effects of longitudinal structural brain changes on the association between regular physical activity and longitudinal cognitive functioning. A total of 120 patients with early PD were included (mean [SD] age = 60.8 [9.3] years; 33% women). Average regular physical activity levels over time were significantly associated with slower cortical thinning in temporoparietal cortical regions, including the lateral temporal cortex, the fusiform gyrus, the parahippocampal gyrus, and the inferior parietal cortex (p < 0.05). Regular physical activity levels over time were also associated with slower volume loss in the hippocampus and the amygdala (p < 0.05). The association of regular physical activity with slower decline in memory and attention functions was mediated by slower decreases in temporoparietal cortical thickness (βPASE-HVLT, = 0.06, p = 0.050; βPASE-SDMT = 0.04, p = 0.017) and hippocampal volume (βPASE-SDMT = 0.03, p = 0.016). Regular physical activity is associated with a slower rate of neurodegeneration in the temporoparietal cortex and limbic areas in PD, which contributes to preserved cognitive function and improved long-term outcomes. This supports regular physical activity as a key intervention to delay disease progression and improve quality of life in patients with PD.