The diagnosis for posttraumatic stress disorder (PTSD) requires that onset be initiated by a negative life event. The event is considered capable of producing PTSD if it creates a threat to the person's physical integrity and produces a reaction of shock and horror. The traumatic events most frequently described in the research literature are combat and rape. These events are well known to produce the three symptom clusters that comprise PTSD and include: (A) re-experiencing symptoms, such as nightmares, sudden unbidden intrusive images and thoughts of the event, and flashbacks; (B) symptoms classified as avoidance, including efforts to avoid thoughts and feelings related to the event, sense of foreshortened future, and emotional numbing; and (C) symptoms of hyperarousal, such as hypervigilance and exaggerated startle response.

The nature of PTSD, particularly that it emerges from significantly disturbing life experiences, may contribute to the limited inquiry about the presence of the disorder among youths. It is difficult to consider that children and teenagers are exposed to terrible events such as physical assault, rape, and mass violence, which frequently lead to sustained psychiatric problems. However, the reality is that children and adolescents experience more violence than adults and that PTSD appears among youth at a rate equivalent to that of adults.