278 Trauma- and Stressor-Related Disorders
Peritraumatic factors
Environmental. These include severity (dose) of th e trauma (the greater the magnitude
of trauma, the greater the likelihood of PTSD), perceived life threat, personal injury, in-
terpersonal violence (particularly trauma pe rpetrated by a caregiver or involving a wit-
nessed threat to a caregiver in children), and,  for military personnel, being a perpetrator,
witnessing atrocities, or killing the enemy. Fina lly, dissociation that occurs during the trauma
and persists afterward is a risk factor.
Posttraumatic factors
Temperamental. These include negative appraisals, inappropriate coping strategies,
and development of ac ute stress disorder.
Environmental. These include subsequent exposure to repeated upsetting reminders, subse-
quent adverse life events, and financial or other trauma-related losses. Social support (includ-
ing family stability, for children) is a protecti ve factor that moderate s outcome after trauma. 
Culture-Related Diagnostic Issues
The risk of onset and severity of PTSD may differ  across cultural groups as a result of vari-
ation in the type of traumatic exposure (e.g., genocide), the impact on disorder severity of
the meaning attributed to the tr aumatic event (e.g., inability to  perform funerary rites after
a mass killing), the ongoing so ciocultural context (e.g., re siding among unpunished per-
petrators in postconflict settings), and other cultural factors (e.g., acculturative stress in
immigrants). The relative risk for PTSD of particular exposures (e .g., religious persecu-
tion) may vary across cultural groups. The clin ical expression of the symptoms or symp-
tom clusters of PTSD may vary culturally, particularly with respect to avoidance and