The fourth edition of Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) defines posttraumatic stress disorder (PTSD) as a reaction to an event, either personally experienced or witnessed, that involves actual or threatened death or serious injury or a threat to the physical integrity of self or others.
As well, the response to the traumatic event must involve intense fear, helplessness, or horror.
The three principal symptoms of PTSD are
- re-experiencing the traumatic event ( eg., nightmares, flashbacks, intrusive and recurrent thoughts of the event),
- persistent avoidance of stimuli associated with the trauma and numbing of general responsiveness, and
- increased arousal ( eg., difficulty sleeping, irritability, hypervigilance, difficulty concentrating).
The symptoms must persist for more than four weeks and result in functional impairment.