BDNF and Parkinson disease: As such, neuroinflammation [30–33], imbalance in same neurotransmitter (e.g., dopamine in Sz and PD [34, 35], serotonin in Sz and UD [36]) and growth factors (e.g., brain-derived neurotrophic factor; BDNF) [37, 38], and disturbed connectivity (e.g., in default-mode network) [39–42] have been implicated in the pathophysiology of many of these brain disorders.