Posttraumatic Stress Disorder 495
an emotional response to the trauma criterion (A2) was intended to make the diagnosis
of PTSD more stringent (Norris & Slone, 2007).
Clinician Guideline 12.1
Posttraumatic stress disorder (PTSD) is a chronic anxiety disorder that occurs in response
to one or more traumatic stressors and is characterized by trauma- related intrusive reexpe-
riencing symptoms, avoidance, emotional numbing, and persistent heightened arousal that
causes significant clinical distress or functional impairment.Acute Stress Disorder
Another important development in DSM-IV was the inclusion of acute stress disorder
(ASD) in order to account for initial trauma reactions (i.e., peritraumatic responses)
and to predict subsequent PTSD. This diagnostic category was developed to cover the
1-month gap imposed by PTSD and to account for individuals’ immediate response to
a traumatic stressor that often includes significant dissociative symptoms (Friedman,
Resick, & Keane, 2007). It was based on the notion that dissociative reactions will
impair recovery because they impede access to affect and memories of the traumatic
experience (Harvey & Bryant, 2002). Table 12.2 presents the DSM-IV diagnostic cri-
teria for ASD.
There has been considerable controversy over the diagnostic and predictive valid-
ity of ASD. The core element of the disorder is the presence of prominent dissociative
symptoms (Criterion B). DSM-IV-TR defines dissociation as “a disruption in the usually
integrated functions of consciousness, memory, identity, or perception” (APA, 2000), as
indicated by derealization, flashbacks, depersonalization, out-of-body experiences, sense
of time slowing down or speeding up, emotional numbing, and inability to remember
aspects of the traumatic experience. McNally (2003b) argues that defined in this way,
the construct of dissociation is too vague, abstract, and global to offer any explanatory
power. Furthermore, Panasetis and Bryant (2003) found that persistent or ongoing dis-
sociation may be related to posttraumatic reactions whereas peritraumatic dissociation
that occurs during the traumatic event may have a more adaptive function.
ASD occurs in 13–33% of adults and 17–21% of children and adolescents exposed
to traumatic events (e.g., Brewin, Andrews, Rose, & Kirk, 1999; Classen, Koopman,
Hales, & Spiegel, 1998; Bryant & Harvey, 1998; Harvey & Bryant, 1998b; Kangas,
Henry, & Bryant, 2005; Meiser- Stedman, Dalgleish, Smith, Yule, & Glucksman, 2007).
Although 75–80% of individuals with ASD will subsequently meet diagnostic criteria
for PTSD (Brewin et al., 1999; Bryant & Harvey, 1998; Harvey & Bryant, 1998b),
ASD may not be the optimal predictor of PTSD (see review by Harvey & Bryant, 2002)
because (1) a diagnosis of ASD does not predict significantly better than preexisting
PTSD criteria, (2) many people develop PTSD without an initial ASD, (3) only a subset
of ASD symptoms predicts PTSD whereas others do not, and (4) ASD might overpathol-
ogize a transient adaptive response to traumatic stress (Bryant, 2003; Harvey & Bry-
ant, 2002; Shalev, 2002). Despite these doubts about its predictive validity, CBT is an
effective treatment for ASD in terms of reducing the subsequent development of PTSD
(Bryant, Moulds, & Nixon, 2003; Bryant et al., 2006).