There are two primary mechanisms of change thought to under-lie efficacious treatment of posttraumatic stress disorder (PTSD): (1) Improvement occurs through emotional processing of the trauma memory by way of repeated exposure, and/or (2) improvement occurs because the meaning of the event changes (Brewin, Dalgleish, & Joseph, 1996
; Ehlers & Clark, 2000
; Foa & Jaycox, 1999
; Keane & Barlow, 2002
; Resick, 2001b
). Consistent with such theories, most therapies that have been developed and tested for PTSD have tended to include repeated in vivo and/or imaginal exposure, some type of cognitive intervention, or a combination of exposure and cognitive therapy. Such approaches have accumulated empirical support in the treatment of PTSD (Bryant, Moulds, Guthrie, Dang, & Nixon, 2003
; Ehlers et al., 2003
; Foa et al., 1999
; Foa, Rothbaum, Riggs, & Murdock, 1991
; Marks, Lovell, Noshirvani, Livanou, & Thrasher, 1998
; Resick, Nishith, Weaver, Astin, & Feuer, 2002
; Schnurr et al., 2007
Nonetheless, the outcomes of such approaches leave room for improvement, with approximately 20%–50% of treatment completers continuing to be diagnosed with PTSD after treatment (Resick et al., 2002
; Schnurr et al., 2007
). In response, researchers have begun to examine the effects of various treatment components, in which components are examined singly and in combination, or a new component is added to an existing protocol (Bryant et al., 2003
; Foa et al., 2005
; Marks et al., 1998
; Paunovic & Öst, 2001
). Published results thus far have been mixed. Marks et al. (1998)
compared exposure, cognitive restructuring (CR), the combination, and a relaxation training control condition. The combination of the two active components was no more efficacious in treating PTSD than exposure or CR alone, although all three exposure and cognitive interventions were more efficacious than relaxation training. Paunovic and Öst (2001)
conducted a study with a small sample comparing exposure with a combination of exposure, CR, and breathing retraining and found no differences between the treatments. Foa et al. (2005)
compared prolonged exposure (PE) with PE plus CR and also found no improvement with the combination. In contrast, Bryant et al. (2003)
compared exposure with exposure plus CR and found that the combination was more efficacious than exposure alone.
There are several possible explanations for the discrepancy in outcomes across these studies. One is that the sample sizes were not large enough to detect the rather small effects expected between active interventions (Schnurr, 2007
). Another possible explanation is that the CR that was offered may have been different across the studies. It appears that Foa et al.’s (2005)
and Paunovic and Öst’s (2001)
CR was more present-focused with an emphasis on current fear cognitions, and Marks et al.’s (1998)
and Bryant et al.’s (2003)
studies may have used a more trauma-focused cognitive intervention. However, more problematic is the very nature of additive studies themselves.
When one develops a therapy protocol with particular session length and number of sessions that is considered optimal for that protocol and then attempts to add components in an additive study, the combination treatment typically suffers because the original components must be condensed to accommodate the new component. The combination treatment may not be delivered in an optimal manner because not enough time is spent on either component to reach a therapeutic dose. For example, in Foa et al.’s (1999)
study comparing PE, stress inoculation training (SIT), and the combination of SIT and PE (SIT/PE), 56% of the PE group was evaluated to have good end state functioning compared with 36% of the SIT/PE group. In Foa et al.’s (2005)
study comparing PE with the combined PE/CR condition, they found that the pre- to posttreatment effect sizes (ESs) were a standard deviation less for the combined condition than the PE only condition. Clearly, even an efficacious intervention, such as exposure therapy, is diminished when less session time is spent on exposure to accommodate the addition of SIT or CR.
Further, the temporal ordering of the therapeutic components in an additive study could also detract from the overall efficacy of the intervention beyond the abbreviation of the components in an additive design. For example, if one were to add CR or SIT after exposure has just been completed, it could have diminishing returns compared with having those components precede the exposure. To truly test an additive design, one would have to counter-balance the temporal ordering of the components in addition to the amount of actual time spent on each element.
An alternative approach to the additive study is the dismantling study. In a dismantling design, the components of a treatment are examined separately and in combination to disentangle the relative utility of various components. For example, in the 1970s, many studies were designed to examine individual components of systematic desensitization for simple phobias until it was concluded that neither the relaxation nor the hierarchical presentation of feared stimuli were required beyond exposure for a therapeutic effect. The dismantling approach has two distinct advantages relative to the additive approach. First, as treatment components are administered as stand-alone treatment packages, there is no need to condense any one component. Second, the temporal ordering of treatment components is no longer problematic; the full treatment package can be administered as it was originally designed.
Nonetheless, dismantling studies pose their own unique challenges and may have potential drawbacks. Because components are pulled out and expanded to fill time, they must stand as viable therapies on their own. To equate time spent in treatment across conditions, a client will receive more of a given component than he or she would if the full treatment package had been administered. Treatment components may also be changed in ways that increase or decrease therapist– client time together. Additionally, it may not be possible to dismantle a treatment such that there are no overlapping procedures across conditions. For example, a cognitive intervention may also contain at least minimal exposure elements because discussing trauma-related cognitions almost certainly necessitates talking about the trauma. Furthermore, when clients talk about reactions to the exposure therapy, such discussion could be construed as a cognitive intervention. Such threats to internal validity may have the effect of influencing the interpretation of the results.
Cognitive processing therapy (CPT) for PTSD was originally developed with both cognitive therapy and written trauma accounts. Both components were initially incorporated into the 12-session protocol, so neither component would have to be shortened or condensed in a dismantling study. Thus, with CPT, it is possible to conduct a dismantling study to determine whether both components are essential and contribute to successful outcomes.
CPT was first tested with rape victims in a group format (Resick & Schnicke, 1992
), followed by a clinical trial in which individually administered CPT was compared with PE and a wait-list control group (Resick et al., 2002
). The results of that trial showed no statistical differences between CPT and PE on the primary outcome variables of PTSD and depressive symptoms. There were, however, small to medium ES differences favoring CPT on those measures. A statistical effect did emerge between conditions on guilt cognitions, with large ES differences favoring CPT over PE. Both treatments resulted in markedly improved symptoms compared with the waiting list condition, which did not improve. Chard (2005)
tested a group and individual adaptation of CPT for adult survivors of child sexual abuse compared with a waiting list control and found CPT to be very efficacious in reducing PTSD and other comorbid symptoms. Recently, CPT was tested in a randomized trial with military veterans and was also found efficacious (Monson et al., 2006
). Similarly, in community settings, CPT was found to be effective with incarcerated adolescents (Ahrens & Rexford, 2002
) and refugees, even when delivered through an interpreter (Schulz, Resick, Huber, & Griffin, 2006
In the traditional administration of CPT, the cognitive component is predominant, with the trauma account element consisting of two sessions that include writing about the worst traumatic event, reading it back to the therapist, and processing emotions. Clients are also asked to read the account at home between sessions on a daily basis. There is built-in latitude within the CPT protocol to assign clients further written accounts (WAs) at home if helpful. The therapist then uses Socratic questioning to challenge the clients’ erroneous conclusions about the event. The development of the dismantling design included changing CPT to the cognitive therapy only (CPT-C) condition, which required the elimination of the two exposure sessions and a greater focus on Socratic questioning. Developing the WA condition of the dismantling design was more challenging because one must expand the therapy to fill 12 hrs of writing, reading the WAs back to the therapist, and conducting emotion-focused non-CR processing with the therapist. We accomplished this by having the participants write their accounts during part of the session and having the reading of accounts and support work during the other half. Piloting indicated that we could not accomplish this with 1-hr sessions because participants could not typically write their account in only 30 min. We used PE as a guide to the therapy structure and configured the WAs to be implemented faithfully to CPT but also as close as possible to the way PE was implemented in the previous trial comparing CPT and PE (Resick et al., 2002
) with 2-hr sessions after the first two introductory 1-hr sessions.
The primary purpose of this study was to examine the components of CPT, singly and compared with the full protocol. We hypothesized that the original CPT protocol would be more efficacious than either component—CPT-C or WA—administered alone, although we also planned to compare CPT-C with WA to determine whether either single component was superior to the other. The design of the study, which included assessment of PTSD and depressive symptoms throughout therapy, as well as before and after, allowed for a powerful examination of change across conditions and time.
Using data from Resick et al.’s (2002)
clinical trial comparing CPT with PE and a waiting list condition, Nishith, Resick, and Griffin (2002)
conducted curve estimation techniques and found that PTSD scores during treatment were quadratic rather than linear. In other words, PTSD scores tended to increase slightly before decreasing. Thus, a secondary purpose of this study was to examine patterns of change to determine whether those findings are replicated and to determine when change occurs during the course of treatment. Finally, in this study we aimed to expand the investigation of the effects of the three therapy conditions on a range of comorbid symptoms known to be associated with posttrauma functioning. The relationships among treatment and depression, anger, anxiety, and cognitions (including guilt, shame, and other dysfunctional cognitions) were also examined.