PMDD
PMDD PMS
See Premenstrual Dysphoric Disorder (PMDD)
See Premenstrual Dysphoric Disorder (PMDD)
POSTTRAUMATIC STRESS DISORDER Posttraumatic stress disorder (PTSD) is a disorder in which the survivor of a traumatic or severely stressful event re-experiences the traumatic event exactly as it happened, both in nightmares and in daytime flashbacks. Unlike dreams, these flashbacks can seem completely real, as though the event is actually occurring again. In addition to recurrent, intrusive thoughts, symptoms of PTSD also include increased physiological arousal and anxiety, which result in insomnia, irritability, difficulty concentrating, and loss of interest in familiar activities. These symptoms may recur for months, years, or even decades, and it may be years after the trauma before the first appearance of symptoms. PTSD was first documented among combat veterans, who appear to be especially vulnerable to the disorder. According to one estimate, more than onethird of men who engaged in heavy combat in Vietnam have shown signs of PTSD. Although the disorder is closely identified in the public eye with Viet Nam, it has been known to doctors who work with soldiers since World War I. At that time it was called shell shock, the idea being that the men had been affected by shells exploding at such close proximity to them that the explosion literally rattled their brains. Veterans of World War II have also experienced PTSD, and many reported waking up shaking and sweating from nightmares, more than half a century later. The magnitude of the problem among WWII veterans took a long time to become apparent: one recent study reports that some veterans who functioned normally throughout their postwar lives have been developing PTSD symptoms upon retirement. Although the syndrome was first identified in combat veterans, PTSD can strike anyone who has experienced a severe trauma, including natural disasters, automobile accidents, sexual abuse, and violent crimes, among other experiences. Most people who experience trauma, however, do not develop PTSD, and so research has been driven by the question of why some people do. Several factors, both physiological and psychological, have been found to distinguish trauma survivors with PTSD from those who did not develop it. People with PTSD tend to be more likely than more resilient survivors to have a relatively small hippocampus (a small subcortical brain structure involved in memory), below-average intelligence, and an elevated level of the personality trait neuroticism (see “Big Five” Personality Factors). As with all correlational data, it is possible that these differences could all be caused by having PTSD, rather than the other way around, but that hypothesis has been refuted by recent research using magnetic resonance imaging (MRI)— at least where the hippocampus is concerned. A research team located a sample of sets of identical twins in which one twin was a Viet Nam veteran and the other was not and used MRIs to examine the size of their respective hippocampi. If hippocampus size is affected by combat, then the veterans with PTSD should 194