• Type I trauma includes single, one-time events such as rape, accidents, natural disasters, or witnessing the death of a loved one (Terr, 1991).
• Type II trauma involves multiple, prolonged, or chronic events, such as child abuse or captivity (Terr, 1991). There are several types of events that can be traumatic.
• Natural disasters, so-called “acts of God,” that typically affect entire groups of people, e.g., hurricanes, earthquakes, tsunamis, fires.
• Stressful events that do not typically lead to trauma-related disorders in most people, but may do so in some individuals, e.g., childbirth, death of a loved one.
• Unintentional accidents caused by human error, e.g., many car accidents, building collapse, fire, a child playing with a gun and accidentally shooting a playmate.
• Acts of gross negligence, e.g., accidents caused by drunk drivers; collapse of building due to inferior construction; neglect of a child leading to a serious accident.
• Intentional interpersonal violence, e.g., arson, assault, domestic violence, child abuse, rape, war, genocide, torture

• Acute Stress Disorder (ASD) is only one of two disorders (along with PTSD) that are defined by DSM-IV as being directly related to a traumatic event. ASD begins no more than four weeks after a stressful event and lasts from two days to four weeks. When the symptoms persist beyond four weeks, the diagnosis becomes PTSD. ASD is strongly predictive of subsequent PTSD (Brewin, Andrews, Rose, & Kirk, 1999; Classen, Koopman, Hales, & Spiegel, 1998; Grieger et al., 2000; Harvey & Bryant, 1998). Thus, some authors argue have suggested that ASD be subsumed under PTSD (e.g., Marshall, Spitzer, & Liebowitz, 1998). Even though ASD is listed as an anxiety disorder, its diagnosis is partly made on the basis of having three or more so-called dissociative symptoms, and like PTSD, many consider it to be a dissociative disorder. Additional criteria include persistent reexperiences, marked avoidance of trauma-related stimuli, and marked hyperarousal or anxiety.

PTSD began to be recognized formally as a serious psychological problem in combat veterans of World War I. At that time it was called “shell shock.” In World War II it was referred to as “combat neurosis.” Only after the Vietnam War did the name “posttraumatic stress disorder” evolve, and eventually it was recognized that PTSD was not unique to male soldiers, but affected survivors of other kinds of traumatic events. Although PTSD is currently listed in DSM-IV as an anxiety disorder, many have proposed that it is a dissociative disorder (Brett, 1996; Chu, 1998; van der Hart et al., 2004, 2006).

PTSD is acute when the duration of symptoms is less than three months, is chronic when the symptoms last three months or longer, and has a delayed onset when at least six months have passed between the traumatizing event and the onset of symptoms. In addition to exposure to a potentially traumatizing event, PTSD requires persistent reexperiences (Criterion B), persistent avoidance(Criterion C), persistent hyperarousal (Criterion D), and duration of symptoms for more than one month (Criterion E) (APA, 1994).

Trauma survivors with PTSD feel chronically afraid that the event is happening or is going to happen, and are unable to fully realize the traumatic event is over. Sometimes they involuntarily relive the event to such a degree that they are unable to maintain contact with present reality; these experiences are called “flashbacks”. At the same time, they avoid remembering as much as possible, and as stimuli in daily life trigger memories, they begin to avoid more and more of life. They may feel intense shame and guilt, thinking that they are somehow responsible for what happened, or guilty for what he or she did in order to survive. With chronic hyperarousal, they feel exhausted, have sleep problems, have difficulty concentrating, and are irritable and jumpy. They may purposefully avoid sleep because of terrifying nightmares. Due to emotional numbing they lose feeling a sense of being connected to others, withdraw from loved ones, and may lash out due to irritability, causing whatever support they have to slowly disappear. They may begin to drink, use drugs, work too much, or engage in other self-destructive behaviors to avoid the feelings and memories of what happened.

Most patients with PTSD (about 80%) have “comorbid” (meaning co-occuring) symptoms in addition to reexperiencing, avoidance, and hyperarousal. If they have many comorbid symptoms, they may qualify for the diagnosis of additional mental disorders (e.g., van der Kolk, Pelcovitz, Mandel, & Spinazzola, 2005). These include anxiety, mood, and substance abuse disorders (McFarlane, 2000), dissociative disorders (e.g., Johnson, Pike, and Chard, 2001), somatic complaints (e.g., van der Kolk et al., 1996), attention deficit hyperactivity disorder (Ford et al., 2000), and personality changes and personality disorders (Southwick, Yehuda, & Giller, 1993).