Female sex is a risk for AD and estrogen has been shown to reduce MAO-A mRNA in the macaque dorsal raphé (Gundlah et al., 2002) and several regions of the rat brain (Holschneider et al., 1998), while progesterone affects platelet MAO (i.e., MAO-B) activity (Klaiber et al., 1996). This evidence concerns the gene MAOA and Alzheimer disease.