Posttraumatic Stress Disorder 499
Clinician Guideline 12.4
Most adults will experience at least one Criterion A traumatic stressor, with the prevalence
higher in men than in women. Although the majority of individuals experience PTSD symp-
toms as an immediate response to trauma, only a small fraction will subsequently develop
DSM-IV PTSD.Vulnerability and the Development of PTSD
Given the discrepancy between the high prevalence of trauma and the much lower rate
of PTSD, a considerable amount of research has focused on potential vulnerability fac-
tors in the disorder. Vulnerability constructs fall into three categories: (1) the enduring
vulnerability factors that are present prior to a trauma, (2) the characteristics of the
traumatic experience, and (3) features of the posttrauma context and the individual’s
coping responses.
Pretrauma Vulnerability Factors
A large meta- analysis was conducted on 77 studies that investigated a variety of risk fac-
tors that predicted PTSD in military and civilian samples exposed to trauma (Brewin,
Andrews, & Valentine, 2000). They found different risk factors for each group. In civil-
ian samples the following pretrauma variables had small effect sizes for PTSD: (1) being
female; (2) low socioeconomic status; (3) a positive psychiatric history; (4) reported
history of abuse, other traumatic experiences, or childhood adversity; and (5) family
psychiatric history. For the military studies, younger age, lack of education, and minor-
ity status emerged as additional pretrauma variables but gender was no longer a sig-
nificant predictor. However, these pretrauma variables were much weaker predictors of
risk than trauma severity or posttrauma variables like lack of social support and more
subsequent life stress.
A more recent meta- analysis of 476 studies confirmed that pretrauma variables like
history of prior trauma, previous psychological or psychiatric problems, and family his-
tory of psychopathology had small but significant effect sizes in predicting PTSD (Ozer,
Best, Lipsey, & Weiss, 2003). Other studies have shown that number of stressful events
prior to the trauma (Galea et al., 2002; Vrana & Lauterbach, 1994) and history of child
sexual abuse in women survivors of sexual assault predicted severity of PTSD symptoms
(Ullman, Filipas, Townsend, & Starzynski, 2007). Breslau (2002) concluded that previ-
ous psychiatric disorders, history of childhood trauma, and family history of psychiatric
disorders were the pretrauma risk factors most consistently associated with PTSD.
Trauma Characteristics
The type of trauma, its severity, and the individual’s emotional response are more
potent predictors of subsequent PTSD than any of the pretrauma variables. Personal
involvement in a traumatic event is associated with increased risk for PTSD compared
to witnessing the event or hearing (i.e., vicarious exposure) about a family member’s