SynopsisTraumatic stress has a broad range of effects on the brain. Brain areas implicated in the stress response include the amygdala, hippocampus, and prefrontal cortex. Studies in patients with posttraumatic stress disorder (PTSD) and other psychiatric disorders related to stress have replicated findings in animal studies by finding alterations in these brain areas. Brain regions implicated in PTSD also play an important role in memory function, highlighting the important interplay between memory and the traumatic stress response. Abnormalities in these brain areas are hypothesized to underlie symptoms of PTSD and other stress-related psychiatric disorders.
EFFECTS OF TRAUMATIC STRESS ON THE INDIVIDUALTraumatic stressors including childhood abuse can lead to posttraumatic stress disorder (PTSD), as well as depression [1,2], substance abuse [3,4], dissociative disorders [5], personality disorders [6,7], and health problems [8]. For many trauma victims, PTSD, which affects about 8% of Americans at some time in their lives [3], may be a life-long problem [9]. However, the development of effective treatments is limited by gaps in knowledge about the underlying neurobiological mechanisms that mediate symptoms of trauma related disorders like PTSD. Until twelve years ago, no brain imaging studies had been performed in patients with PTSD or other stress-related psychiatric disorders. The past decade has seen an explosion of research using brain imaging to assess the effects of traumatic stress on the brain [10]. These studies have implicated the amygdala, hippocampus, and medial prefrontal cortex (including anterior cingulate) in PTSD and other stress related psychiatric disorders. This chapter reviews brain imaging studies looking at the effects of traumatic stress on the brain, and integrates them with basic science findings on the neuroscience of stress.
NEURAL CIRCUITS OF PTSDPTSD is characterized by specific symptoms, including intrusive thoughts, hyperarousal, flashbacks, nightmares, and sleep disturbances, changes in memory and concentration, and startle responses. Symptoms of PTSD are hypothesized to represent the behavioral manifestation of stress-induced changes in brain structure and function. Stress results in acute and chronic changes in neurochemical systems and specific brain regions, which result in longterm changes in brain "circuits" involved in the stress response [11][12][13][14]. Brain regions that are