BDNF and Parkinson disease: Noteworthy, the PI3K/Akt axis exerts a neuroprotective effect in neurodegenerative diseases, such as ischemic stroke, PD, and AD via enhancement of cAMP-responsive element-binding protein (CREB) expression with subsequent downstream protein, brain-derived neurotrophic factor (BDNF) leading to cellular proliferation and inhibition of apoptotic and inflammatory biomarkers that eventually ends up with improved cell survival (Jiang et al., 2013; Heras-Sandoval et al., 2014; Ribeiro et al., 2014; Zuo et al., 2016).