BDNF and Alzheimer disease: In that light, it is not surprising that mRNA (Connor et al.1997; Garzon et al.2002; Holsinger et al.2000; Phillips et al.1991) and protein (Ferrer et al.1999; Hock et al.2000a; Michalski & Fahnestock 2003; Peng et al.2005) levels of BDNF are decreased in hippocampus and neocortex of AD brains (for review, see Murer et al.2001; Siegel & Chauhan 2000).