It is believed the locus coeruleus-noradrenergic procedure mediates the more than-consolidation of dread memory. Substantial amounts of cortisol reduce noradrenergic activity, and because people with PTSD have a tendency to acquire reduced levels of cortisol, it's been proposed that people with PTSD are not able to control the amplified noradrenergic https://brainhealthusa.com/post-traumatic-stress-disorder-ptsd-brain-health-usa/