Witnessed events include, but are not limited to, observing threatened or serious in- jury, unnatural death, physical or sexual violence inﬂicted on another individual as a re- sult of violent assault, severe domestic violence, severe accident, war, and disaster; it may also include witnessing a medical catastrophe (e.g., a life-threatening hemorrhage) involv- ing one’s child. Events experienced indirectly through learning about the event are limited to close relatives or close friends. Such events must have been violent or accidental—death due to natural causes does not qualify—and include violent personal assault, suicide, se- rious accident, or serious injury. The disorder may be especially severe when the stressor is interpersonal and intentional (e.g., torture, rape). The likelihood of developing this dis- order may increase as the intensity of and physical proximity to the stressor increase.
The traumatic event can be reexperienced in various ways. Commonly, the individual has recurrent and intrusive recollections of the event (Criterion Bl). The recollections are spontaneous or triggered recurrent memories of the event that usually occur in response to a stimulus that is reminiscent of the traumatic experience (e.g., the sound of a backfiring car triggering memories of gunshots). These intrusive memories often include sensory (e.g., sensing the intense heat that was perceived in a house fire), emotional (e.g., experi- encing the fear of believing that one was about to be stabbed), or physiological (e.g., expe- riencing the shortness of breath that one suffered during a near-drowning) components.
Distressing dreams may contain themes that are representative of or thematically re- lated to the major threats involved in the traumatic event. (For example, in the case of a motor vehicle accident survivor, the distressing dreams may involve crashing cars gener- ally; in the case of a combat soldier, the distressing dreams may involve being harmed in ways other than combat.)
Dissociative states may last from a few seconds to several hours, or even days, during which components of the event are relived and the individual behaves as though experi- encing the event at that moment. While dissociative responses are common during a trau- matic event, only dissociative responses that persist beyond 3 days after trauma exposure are considered for the diagnosis of acute stress disorder. For young children, reenactment of events related to trauma may appear in play and may include dissociative moments (e.g., a child who survives a motor vehicle accident may repeatedly crash toy cars during play in a focused and distressing manner). These episodes, often referred to as ﬂashbacks, are typically brief but involve a sense that the traumatic event is occurring in the present rather than being remembered in the past and are associated with significant distress.
Some individuals with the disorder do not have intrusive memories of the event itself, they are exposed to triggering events that resemble or symbolize an aspect of the traumatic event (e.g., windy days for children after a hurricane, entering an elevator for a male or fe- male who was raped in an elevator, seeing someone who resembles one’s perpetrator).
The triggering cue could be a physical sensation (e.g., a sense of heat for a burn victim, diz- ziness for survivors of head trauma), particularly for individuals with highly somatic pre- sentations. The individual may have a persistent inability to feel positive emotions (e.g., happiness, joy, satisfaction, or emotions associated with intimacy, tenderness, or sexual- ity) but can experience negative emotions such as fear, sadness, anger, guilt, or shame.