Patients must have Emotional or behavioral symptoms within 3 months of having been exposed to a stressor Symptoms must be clinically significant as shown by ≥ 1 of the following: Marked distress that is out of proportion to the stressor (taking cultural and other factors into consideration) The symptoms significantly impair social or occupational functioning Posttraumatic stress disorder (PTSD) and acute stress disorder are part of the differential diagnosis but have different time frames and more specific descriptors of the stressors and the patient's response.