Numerous studies have demonstrated the potent protective effects of BDNF on dopaminergic neurons in animal parkinsonian models (Tsukahara et al., 1995; Fumagalli et al., 2006; Stahl et al., 2011), and BDNF is considered to be involved in the beneficial effects of exercise in PD (Real et al., 2013; Angelucci et al., 2015). Here, BDNF is linked to Parkinson disease.