Percent change BDNF levels were reported from two pre-experimental studies (Marusiak et al. [62], Angelucci et al. [63] Table 1), with a total of 20 ambulatory in- and outpatients with mild to moderate idiopathic PD severity (Hoehn and Yahr stage ≤3, range 1-3), 9.8±6.0 years (range 2-26 years) after PD diagnosis and 66.8±8.3 years of age at the time of study enrollment. Here, BDNF is linked to Parkinson disease.