BDNF and Alzheimer disease: We, thus, hypothesize that changes in AD are the smallest common dominator in schizophrenia patients, whereas our findings of a negative correlation of BDNF and FA values are a result of increased BDNF levels due to more global fiber tract changes, as FA is a summative parameter for microstructural integrity (e.g., axonal diameter and packing density, myelination, etc.)(86, 87).