BDNF and Parkinson disease: Multiple lines of evidence have demonstrated the beneficial effects of exercise on PD pathophysiology including the following: (1) improvement of striatal dopamine (DA) release and transmission20,21, (2) reversion of aberrant glutamatergic synaptic drive in the corticostriatal pathway22, (3) elevated expression of neurotrophic factors such as brain-derived neurotrophic factor (BDNF)23,24, and (4) improvement in mitochondrial dysfunction such as biogenesis- and fusion-associated abnormalities25,26.