BDNF and Alzheimer disease: Traditional candidate–gene approaches have mainly focused on genes involved in pathways of neurodegeneration, such as mitochondrial transcription factor A (TFAM) or brain derived neurotrophic factor (BDNF); alternatively, genes like apolipoprotein E (APOE) and microtubule-associated protein Tau (MAPT), were selected among those previously associated with AD (24).