CRH and depressive disorder: Depressed individuals also have heightened levels of CRF mRNA in BNST and amygdala (Merali et al., 2006) which, given the high levels of comorbidity between PTSD and depression (Kessler et al., 1995; Flory and Yehuda, 2015), further implicates CRF as a critical component of PTSD symptomology.