Clinical studies have shown that increased concentrations of CRF in the CSF are associated with PTSD (Post et al., 1982) and several studies have found altered hypothalamic pituitary adrenal (HPA) axis and CRF function in PTSD (Mason et al., 1986; Smith et al., 1989; Pitman and Orr, 1990; Yehuda et al., 1993). Here, CRH is linked to post-traumatic stress disorder.