Increased cortisol can enhance neurotoxicity, promote neurodegeneration, and inhibit neuroplasticity and hippocampal neurogenesis through different mechanisms including effects on the brain-derived neurotrophic factor (BDNF) (Suri and Vaidya, 2013), as well as effects on long-term potentiation (Sale et al., 2008), and may therefore contribute to atrophy in vulnerable regions in AD. This evidence concerns the gene BDNF and Alzheimer disease.