Decreased expression levels of BDNF protein and mRNA have been consistently reported in the hippocampus and cortex of individuals with AD (Phillips et al., 1991; Connor et al., 1997; Hock et al., 2000; Holsinger et al., 2000) as well as in serum (Laske et al., 2007). The gene discussed is BDNF; the disease is Alzheimer disease.