Posttraumatic Stress Disorder 523
associated with PTSD symptoms (Meiser- Stedman et al., 2007; Steil & Ehlers, 2000),
but this may not be disorder- specific since presence of rumination about trauma and its
consequences may also be evident in traumatized individuals who suffer from depres-
sion or specific fears (Ehring et al., 2006).
There has been a great deal of research interest in the prevalence and impact of
deliberate efforts to suppress trauma- related intrusions in PTSD. Self- report studies have
found significantly higher rates of thought suppression in traumatized individuals with
PTSD compared with non-PTSD controls (Ehring et al., 2006), and suppression was
associated with increased symptom severity especially higher levels of intrusive thoughts
(Laposa & Alden, 2003; Morgan et al., 1995). Nonclinical individuals who were shown
a 3-minute film clip of a traumatic fire and who reported a stronger tendency to sup-
press unpleasant thoughts recorded more intrusions in a diary of intrusions kept over
the subsequent week (Davies & Clark, 1998b). In a study of women who experienced
pregnancy loss, thought suppression was 1 of 4 variables that mediated the relation-
ship between peritraumatic dissociation and PTSD symptoms assessed at one and four
months after the pregnancy loss (Engelhard et al., 2003). These correlational studies,
then, indicate that deliberate thought suppression may be a maladaptive coping strategy
that is associated with the persistence of PTSD.
A number of experimental studies have shown that active efforts to suppress
trauma- relevant thoughts paradoxically lead to a significant increase in the unwanted
intrusions, especially when suppression efforts cease. In an early thought suppression
study, Harvey and Bryant (1998a) found that ASD participants who were instructed to
suppress their trauma- related thoughts had significantly more trauma- related intrusions
after suppression efforts ceased than those instructed not to suppress. However, Guthrie
and Bryant (2000) failed to replicate this finding in a group of civilian trauma survivors
with or without ASD. A more direct investigation of the role of thought suppression
in PTSD was conducted by Shipherd and Beck (1999). Female sexual assault survi-
vors with PTSD evidenced a significant rebound of rape- related thoughts after suppres-
sion efforts ceased, whereas assault survivors without PTSD did not show this rebound
effect. Likewise, Amstadter and Vernon (2006) found that individuals with and with-
out PTSD experienced immediate enhancement of trauma and neutral thoughts during
suppression, but only the PTSD group had a postsuppression rebound effect that was
specific to the trauma thoughts. Furthermore, individuals with a repressive coping style
may be more successful suppressing negative target thoughts in the short term but over
longer time intervals (i.e., 1 week) their repressive style leads to more unwanted negative
thoughts (Geraerts et al., 2006). Although the findings are by no means robust, there
is sufficient evidence to indicate that deliberate suppression of trauma- related intrusive
thoughts is counterproductive in the long run and probably contributes to a higher fre-
quency of intrusive reexperiencing symptoms.
Clinician Guideline 12.19Reduction in maladaptive cognitive strategies such as thought suppression, rumination, and
even dissociation is an important focus in cognitive therapy because these strategies contrib-
ute to the persistence of trauma- related reexperiencing symptoms.