In the central nervous system (CNS), BDNF has been found to be a potent neurotrophic factor for cholinergic neurons, which are depleted in Alzheimer’s disease; for dopaminergic neurons of the substantia nigra, which are lost in Parkinson’s disease; as well as for cerebral and spinal motor neurons, which degenerate in amyotrophic lateral sclerosis (ALS) [12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47]. Here, BDNF is linked to Alzheimer disease.