Acute stress disorder: The anxiety and behavioral disturbances that develop within a month of exposure to extreme trauma. The symptoms of an acute stress disorder usually begin during or shortly following the trauma. Such extreme traumatic events include rape or other severe physical assault, near-death experiences in accidents, witnessing a murder, and combat.
The symptom of dissociation, which reflects a perceived detachment of the mind from the emotional state or even the body, is a critical feature. Dissociation also is characterized by a sense of the world as a dreamlike or unreal place and may be accompanied by poor memory of the specific events, which in severe form is known as dissociative amnesia.
Other features of acute stress disorder include symptoms of generalized anxiety and hyperarousal, avoidance of situations or stimuli that elicit memories of the trauma, and persistent, intrusive recollections of the event via flashbacks, dreams, or recurrent thoughts or visual images.
If the symptoms and behavioral disturbances of the acute stress disorder persist for more than a month, and if these features are associated with functional impairment or significant distress to the sufferer, the diagnosis is changed to posttraumatic stress disorder (PTSD).