ADAA Chief Medical Officer Charles Nemeroff, MD, PHD is quoted in this CNN article: "PTSD is an anxiety disorder that can develop in some people after witnessing or being involved in traumatic events...several studies have shown changes in the brains of patients with PTSD. There is no doubt that PTSD changes the way the brain responds to trauma-related and other emotional stimuli, however there are not brain imaging tests that are diagnostic of PTSD."