274 Trauma- and Stressor-Related Disorders
F. The disturbance causes clinically significant distress or impairment in relationships
with parents, siblings, peers, or other caregivers or with school behavior.
G. The disturbance is not attributable to the physiological effects of a substance (e.g.,
medication or alcohol) or another medical condition.
Specify whether:
With dissociative symptoms:  The individual’s symptoms meet the criteria for post-
traumatic stress disorder, and the individual experiences persistent or recurrent symp-
toms of either of the following:
1.Depersonalization:  Persistent or recurrent experiences of feeling detached from,
and as if one were an outside observer of, one’s mental processes or body (e.g.,
feeling as though one were in a dream; feeling a sense of unreality of self or body
or of time moving slowly).
2.Derealization:  Persistent or recurrent experiences of unreality of surroundings
(e.g., the world around the individual is experienced as unreal, dreamlike, distant,
or distorted).
Note:  To use this subtype, the dissociative symptoms must not be attributable to the
physiological effects of a substance (e.g., blackouts) or another medical condition
(e.g., complex partial seizures).
Specify if:
With delayed expression: If the full diagnostic criteria are not met until at least
6 months after the event (although the onset and expression of some symptoms may
be immediate).
Diagnostic Features
The essential feature of posttraumatic stress disorder (PTSD) is the development of char-
acteristic symptoms following exposure to one or more tr aumatic events. Emotional re-
actions to the traumatic event (e.g., fear, he lplessness, horror) are no longer a part of
Criterion A. The clinical presentation of PTSD  varies. In some individuals, fear-based re-