Posttraumatic stress disorder (PTSD) consists of three clusters of interrelated symptoms: re-experiencing, avoidance/numbing, and hyper arousal. These symptoms develop after an individual experiences a traumatic event. Traumatic events involve actual or threatened death or injury or a threat to an individual's physical integrity. Traumatic events can include events that one actually experienced or events that one witnessed. Examples of traumatic events include physical or sexual assault and abuse, combat, natural disasters, terrorism, and serious illness. According to the criteria for PTSD set forth in the Diagnostic and Statistical Manual of Mental Disorders (4th Ed; DSM-IV), for an individual to develop PTSD, the person must respond to the traumatic event with feelings of intense fear, helplessness, or horror. In addition, to differentiate PTSD from temporary reactions to traumatic experiences, the individual also has to report experiencing symptoms of PTSD for at least 1 month, although in many instances symptoms can persist for years (Perrin, Smith & Yule, 2000).
For an individual to meet criteria for PTSD according to DSM-IV criteria, he or she must experience at least one re-experiencing symptom, three or more avoidance or numbing symptoms, and two or more hyper arousal symptoms. Re-experiencing symptoms include recurrent unwanted thoughts, dreams, or memories of the trauma. Re-experiencing symptoms in children with PTSD may include engaging in play that involves traumatic themes or having frightening dreams without specific traumatic content. In adolescents, re-experiencing symptoms may include re-enacting the trauma in their behaviors (e.g., sexual acting out behavior in an adolescent who experienced sexual abuse). Some individuals also experience reliving phenomenon, which can include the sense that the trauma is re-occurring, illusions, hallucinations, or flashbacks.
Avoidance symptoms include avoidance of reminders of the trauma including trauma-related thoughts, places, and activities, and conversations about the trauma. Some individuals may have amnesia that has no physiological basis for important aspects of the trauma. Numbing symptoms include difficulties experiencing or blunted expression of certain emotions such as love or happiness, feelings of detachment from others, loss of interest in previously enjoyed activities, and a sense of a foreshortened future (e.g., that one will not have a long life, have children, have a career, or have important relationships). Hyper arousal symptoms include insomnia, irritability, outbursts of anger, difficulty concentrating, hyper vigilance to danger cues, and an exaggerated startle response.
Epidemiological surveys of PTSD have primarily been conducted among adults in developed countries. The National Co morbidity Survey (NCS) and National Co morbidity Survey Replication (NCS-R) conducted among residents of the United States found estimated lifetime prevalence rates of PTSD of 7.8% and 6.8%, respectively. Obtained prevalence rates for PTSD in other developed countries have often been lower than U.S. samples. For example, an Icelandic study found a lifetime prevalence of PTSD of 0.6%, an Australian survey found a 12-month PTSD prevalence of 1.3%, and a German study found a lifetime prevalence of PTSD of 1.3%. It is unclear the extent to which these prevalence differences reflect true differences in prevalence rates of ...