Is physical fitness associated with brain structure and function in Parkinson's disease?

We investigated associations between physical fitness (cardiorespiratory fitness (VO2max), peak muscle power (Pmax)) and brain structure (magnetic resonance imaging (MRI) measures) and function (cognition) in people with Parkinson’s disease (pwPD). Simple and multiple linear regression analyses were performed using quantitative susceptibility mapping, diffusion imaging, and volumetric MRI data from 105 pwPD. Simple regression analyses showed significant positive associations between VO2max/Pmax and whole-brain volume (r2 = 0.11/0.12), the Symbol Digit Modalities Test (SDMT) (r2 = 0.18/0.21), the Montreal Cognitive Assessment (MoCA) (r2 = 0.12/0.12) as well as volume of white and gray matter structures (total white/gray matter, putamen, caudate, pallidus, thalamus). When adjusted for age and sex, associations between VO2max and cognition (SDMT, MoCA) and between Pmax and total white matter volume, pallidus volume, and cognition (SDMT) remained significant. Physical fitness was weakly to moderately associated with cognitive function and some MRI markers of neurodegeneration in pwPD. These exploratory findings further support the potential neuroprotective effect of exercise in pwPD and may aid in selecting outcomes in future trials evaluating the neuroprotective effects of exercise.