Posttraumatic Stress Disorder 501
tive beliefs and appraisals of the trauma, its consequences, and PTSD symptoms (for
further discussion, see section below on empirical research of the cognitive model).
Clinical Implications
The research findings on vulnerability and risk for PTSD provide useful information
to incorporate into the education phase of cognitive therapy and can be used in cogni-
tive restructuring to modify negative beliefs and appraisals of initial PTSD symptoms.
Many individuals with PTSD blame themselves for the disorder. Edward, for example,
believed that it was his fault that he suffered from chronic PTSD. He believed there must
be a weakness in his character or some predisposition for mental illness that caused him
to have PTSD while other soldiers returned from deployment without apparent mental
health difficulties. The therapist was able to discuss with Edward the latest research
on risk factors in PTSD, emphasizing that pretrauma variables were only weak predic-
tors of who develops PTSD in military samples and that variables related to severity of
trauma exposure like experiencing threats to one’s life and extent of combat exposure
were the most important predictors of the disorder. We also noted that posttrauma
responses such as coping strategies and ways of thinking about the trauma, oneself, and
the future are important contributors to the persistence of PTSD and these are variables
that can be changed with therapy.
Clinician Guideline 12.5
Peritraumatic and posttraumatic variables are stronger predictors of the development of
PTSD than pretrauma risk factors. This finding can be used to counter maladaptive beliefs
of self-blame that are common in PTSD.CliniCal featuresPrevalence and Course
Epidemiological research on PTSD draws a distinction between prevalence of the disor-
der in the population and conditional prevalence, which examines rates in populations
exposed to trauma (Norris & Slone, 2007). Incidence of PTSD has also been reported
for specific occupations associated with high rates of trauma exposure such as the mili-
tary, police, and emergency rescue workers as well as in response to single community
traumas like a natural disaster (e.g., earthquake) or terrorist attack. Rates of PTSD
have also been examined over time, with the highest rates occurring immediately after
a trauma and then declining steadily over the next 3–6 months.
Population and Occupational Rates of PTSD
The lifetime prevalence for PTSD in the U.S. population was 7.8% in the NCS (10.4%
women, 5.0% men; Kessler et al., 1995) and 6.8% in the NCS-R (Kessler, Berglund,
et al., 2005). An earlier study based on a representative national sample of women (N
= 4,008) reported a lifetime prevalence rate of 12.3% (Resnick et al., 1993). However,