265Trauma- and
 Stressor-Related Disorders
Trauma- and stressor-related  disorders include disorders in which exposure to
a traumatic or stressful event is listed explicitly  as a diagnostic criterion. These include reactive
attachment disorder, disinhibit ed social engagement disorder , posttraumatic stress disor-
der (PTSD), acute stress disorder, and adjustment disorders. Placement of this chapter reflects
the close relationship between these diagnoses and disorders in the surrounding chapters on
anxiety disorders, obsessive-c ompulsive and related disorder s, and dissociative disorders.
Psychological distress following exposure to a traumatic or stressful event is quite vari-
able. In some cases, symptoms  can be well understood with in an anxiety- or fear-based
context. It is clear, however, that many in dividuals who have been exposed to a traumatic
or stressful event exhibit a phenotype in which,  rather than anxiety- or fear-based symp-
toms, the most prominent clin ical characteristics are anhedonic and dysphoric symptoms,
externalizing angry and aggressive symptoms, or  dissociative symptoms. Because of these
variable expressions of clinic al distress following exposure  to catastrophic or aversive
events, the aforementioned di sorders have been grouped under a separate category:
trauma- and stressor-related disorders. Furthermore, it is not uncommon for the clinical pic-
ture to include some combination of the ab ove symptoms (with or without anxiety- or
fear-based symptoms). Such a heterogeneous picture has long been recognized in adjust-
ment disorders, as well. Social  neglect—that is, the absence of adequate caregiving during
childhood—is a diagnostic requirement of both reactive attachment disorder and disin-
hibited social engagement diso rder. Although the two disord ers share a common etiology,
the former is expressed as an internalizing di sorder with depressive symptoms and with-