BDNF and Alzheimer disease: Some scholars believe that neuronal damage caused by decreased DNA repair capacity due to DNA oxidation is often observed in AD, and that BDNF can counteract DNA damage and increase transcription factor activity by increasing protein expression of purine-free/pyrimidine-free nucleic acid endonuclease/oxidation reductase-1 (APE1/Ref-1) through the BDNF/CREB pathway (Yang et al., 2014).