PTSD

Posttraumatic stress disorder is classified as an anxiety disorder; the characteristic symptoms are not present before exposure to the violently traumatic event. In the typical case, the individual with PTSD persistently avoids all thoughts and emotions, and discussion of the stressor event and may experience amnesia for it.

However, the event is commonly relived by the individual through intrusive, recurrent recollections, flashbacks, and nightmares. The characteristic symptoms are considered acute if lasting less than three months, and chronic if persisting three months or more, and with delayed onset if the symptoms first occur after six months or some years later.

PTSD is distinct from the briefer acute stress disorder, and can cause clinical impairment in significant areas of functioning.