FKBP5 is a key molecule in the stress response and a particular single nucleotide polymorphism (SNP) has been implicated in the hypothalamic-pituitary-adrenal (HPA) axis and the development of stress-related psychiatric disorders such as posttraumatic stress disorder (PTSD), as well as the pathophysiology of stress-related disorders and AD [40,41]. Here, FKBP5 is linked to Alzheimer disease.