BDNF and Alzheimer disease: BDNF has been investigated in a number of neurological and psychiatric conditions, including AD (Balietti et al., 2018), MCI (Siuda et al., 2017), Parkinson's Disease (Rahmani et al., 2019), epilepsy (Iughetti et al., 2018), traumatic brain injury (Korley et al., 2016), depression (Molendijk et al., 2014), bipolar disorder (Fernandes et al., 2015a), schizophrenia (Fernandes et al., 2015b), and autism spectrum disorder (Qin et al., 2016).