Structural and functional brain changes following diverse exercise interventions in Parkinson’s disease: an MRI-based narrative review

[Purpose] This narrative review synthesizes magnetic resonance imaging (MRI) evidence from exercise intervention studies in patients with Parkinson’s disease (PD), focusing on structural and functional brain changes associated with motor and cognitive outcomes. We also propose an interpretative framework in which exercise-related neuroplasticity in PD is understood as region- and task-dependent reorganization across cognitive–motor networks.[Methods] PubMed and Web of Science were searched for interventional studies in patients with PD that examined the effects of exercise-based training on motor and/or cognitive outcomes and included MRI-based assessments of brain structure or function. Studies were eligible if they used a randomized controlled or crossover design and were published in English.[Results] Eighteen interventional trials met the inclusion criteria. Structural MRI findings were limited but suggested subtle region-specific changes in the cerebellum, putamen, and hippocampus rather than a uniform global structural response. Resting-state fMRI studies indicated distributed reorganization across both motor and extramotor networks, including the sensorimotor, salience, default mode, frontoparietal, attentional, and medial temporal systems. Task-based fMRI studies further suggested that exercise-related neural adaptation in PD is strongly shaped by task demand, with reduced prefrontal recruitment observed during complex gait-related conditions and increased recruitment of control-related regions during motor imagery or internally simulated tasks.[Conclusion] Exercise interventions in PD may influence motor and cognitive outcomes through neuroplastic changes that are better characterized by circuit-specific structural remodeling, context-dependent resting-state network retuning, and task-dependent functional reallocation rather than by a single uniform neural response.