What parts of PTSD are normal: Intrusion, avoidance, or arousal? Data from the Northridge, California, earthquake

The incidence and comorbidity of posttraumatic stress disorder (PTSD) are addressed in a study of 130 Northridge, California, earthquake survivors interviewed 3 months postdisaster Only 13% of the sample met full PTSD criteria, but 48% met both the reexperiencing and the arousal symptom criteria, without meeting the avoidance and numbing symptom criterion. Psychiatric comorbidity was associated mostly with avoidance and numbing symptoms. For moderately severe traumatic events, reexperiencing and arousal symptoms may be the most "normal" and survivors with a history of psychiatric problems may be those most likely to develop full PTSD. A system that considers people who meet all three symptom criteria to have a psychiatric disorder yet recognizes the distress of other symptomatic survivors may best serve traumatized populations.