Brain markers of cognitive-motor control of gait function in Parkinson’s disease: links with physical activity and aerobic fitness

[Purpose] This narrative review synthesizes magnetic resonance imaging (MRI) evidence of (i) the associations between physical activity and/or aerobic fitness and brain markers related to cognitive function in Parkinson’s disease (PD); and (ii) MRI-derived brain markers linked to gait impairment in PD. We also propose a conceptual framework describing how physical activity or fitness may support the cognitive-motor networks associated with gait.[Methods] PubMed and Web of Science were searched for MRI studies examining the relationships between physical activity/fitness and cognition-relevant brain markers as well as MRI studies linking brain markers to gait outcomes (including cognition-related gait measures and freezing of gait).[Results] Fourteen observational studies met our inclusion criteria. Higher physical activity and/or fitness were seen to be generally associated with better cognitive performance and MRI features suggestive of preserved brain integrity and connectivity within the cognitive-motor networks. Regarding gait, the reviewed evidence suggests a shift toward greater reliance on cognitive-motor control to compensate for impaired automatic motor control, which may occur when this compensatory cognitive control becomes insufficient under increased task demands.[Conclusion] Physical activity and fitness may contribute to gait function in patients with Parkinson’s disease by supporting the cognitive-motor integration required for walking. Longitudinal and interventional studies using ecologically valid paradigms that approximate real-world (including dual-task) walking, ideally combined with wearable neuroimaging approaches, are needed to clarify how changes in physical activity or fitness are related to neural markers of gait.