Structural and Functional Brain Changes in Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is a highly disabling condition that is associated with intrusiverecollections of a traumatic event, hyperarousal, avoidance of clues associated with the trauma,and psychological numbing. The field of neuroimaging has made tremendous advances in the pastdecade and has contributed greatly to our understanding of the physiology of fear and the pathophysiologyof PTSD. Neuroimaging studies have demonstrated significant neurobiologic changes in PTSD.There appear to be 3 areas of the brain that are different in patients with PTSD compared with those incontrol subjects: the hippocampus, the amygdala, and the medial frontal cortex. The amygdala appearsto be hyperreactive to trauma-related stimuli. The hallmark symptoms of PTSD, including exaggeratedstartle response and flashbacks, may be related to a failure of higher brain regions (i.e., thehippocampus and the medial frontal cortex) to dampen the exaggerated symptoms of arousal and distressthat are mediated through the amygdala in response to reminders of the traumatic event. Thefindings of structural and functional neuroimaging studies of PTSD are reviewed as they relate to ourcurrent understanding of the pathophysiology of this disorder.