hyperarousal, duration of symptoms for at least a month, and clinically significant distress or impairment that was not present before the trauma.

Numerous traumatic events or stressors are known to influence the onset of PTSD; however, not everyone who experiences a traumatic event or stressor will develop PTSD. Its development depends on the intensity of the traumatic event or stressor and on a host of risk and protective factors occurring before, during, and after the trauma.

After a traumatic event, there is substantial variation among patients with regard to both the timing of the onset of symptoms and the types of symptoms. Furthermore, there might be a delay between the onset of symptoms and when the patient seeks help. Patients also vary in how they present to a health professional. For example, a patient might present at a health facility with a physical or psychiatric complaint unrelated to PTSD, and it is only during the course of evaluating or treating the patient for the presenting complaint that symptoms of PTSD can be identified and a diagnosis made. In other cases, a patient might present to a mental health professional who is conversant with the diagnosis of PTSD and is better able to elicit a narrative of exposure and symptoms; or a family member or other person familiar with the veteran might seek advice from a health professional about coping with a veteran who might be suffering from PTSD. The presenting symptoms and initial diagnostic process are variable and might necessitate a brief or long assessment.

Optimally, a patient is evaluated in a confidential setting with a face-to-face interview by a health professional experienced in the diagnosis of psychiatric disorders, such as a psychiatrist, psychologist, clinical social worker, or psychiatric nurse. The interview should elicit the patient’s symptoms, assess the history of potentially traumatic events, determine whether the patient meets the DSM-IV criteria for PTSD, determine the frequency and severity of symptoms and the associated disability, and determine whether there are comorbid psychiatric and