BMP4 and Alzheimer disease: The decrease in neurogenesis could be due to changes in the expression of bone morphogenetic proteins (BMPs), a family of proteins involved in adult neurogenesis (Colak et al., 2008), as the decrease in neurogenesis is associated with an increase in BMP6 and BMP4 gene expression in the AD human brain and the AD mouse model (Li et al., 2008; Crews et al., 2010).