Cognitive processing therapy (CPT) has been rigorously examined in randomized clinical trials , and it has been shown to be efficacious in reducing symptoms of PTSD and co-occurring symptoms for many different traumatic events [3]. The first study evaluating the effectiveness of CPT was in 1992 by Resick and Schnicke; this study compared sexual assault survivors who received CPT treatment, in group format, to a wait-list control group [1]. The wait-list control group consisted of individuals who met criteria for PTSD and were on the waiting list for CPT treatment for at least 12 weeks. CPT participants improved significantly from pre- to posttreatment on PTSD and depressive symptoms and maintained their improvement when reassessed after 6-month posttreatment. There was no change observed from pre- to posttreatment for the control group.

Resick and colleagues performed the first randomized controlled trial evaluating CPT in 2002 [7]. This study compared prolonged exposure (PE) [8], CPT, and a minimal attention (MA) waiting list in a sample of female rape victims intended to be treated in the study. The MA waiting list group consisted of participants on the waiting list for treatment for 6 weeks who were called every 2 weeks to ensure they did not need emergency services. Both PE and CPT reduced symptoms of PTSD and depression, as measured by the Clinician-Administered PTSD Scale for DSM-IV (CAPS) [9] and Beck Depression Inventory-II (BDI-II) [10]. CPT and PE were similarly effective in their ability to improve psychological functioning. Resick and her colleagues [7] conducted a follow-up assessment of those previously treated with either PE or CPT in their previous study [3]. The researchers contacted their previous participants with the length of time following completion of treatment ranging from 4.5 to 10 years, averaging 6.15 years (SD = 1.22). Both CPT and PE participants had similar maintenance of improvements in PTSD symptoms at follow-up. These results were not explained by additional psychotherapy posttreatment or medication usage. On the contrary, those who had sought further psychotherapy or had used medication demonstrated a pattern of worse outcomes. This study provides encouraging support for the sustained improvement in PTSD symptoms for those treated with CPT.

The effectiveness of CPT has also been evaluated in veterans by Monson and her colleagues [11]. Similar to results of other CPT studies, veterans who received CPT (compared to those in a wait-list control condition) were significantly less likely to meet diagnostic criteria for PTSD at posttreatment. In terms of a cluster-level symptom examination, results indicated that reexperiencing and numbing symptoms improved in the CPT condition but behavioral avoidance and hyperarousal symptoms did not change regardless of treatment group .

Resick and her colleagues were interested in examining the components of CPT to assess if one individual component may be the most effective in treating PTSD [12]. One dismantling study examined CPT outcomes among female victims of sexual assault. The standard protocol was broken down into cognitive processing therapy-cognitive (CPT-C) and written accounts (WA) , which were both compared to a standard CPT condition. The CPT-C condition consisted of 12 sessions over 6 weeks and included all of the modules of CPT without the written accounts of trauma narratives. The WA condition consisted of two one hour sessions in the first week and five two hours sessions once a week for the remaining 5 weeks. The WA condition included writing trauma narratives, reading them to the therapist, and engaging in an emotion-focused non-cognitive restructuring.

The results of this study indicate that all three conditions evidenced decreased PTSD symptoms. Similar to other studies of CPT, the decrease in PTSD symptoms was maintained through the follow-up assessments. The results indicated that the standard condition CPT was not significantly better at reducing PTSD symptoms than WA or CPT-C alone. The CPT-C group had significantly lower scores on the Posttraumatic Diagnostic Scale [13] than the WA group, while the CPT condition did not differ from either. These results indicate that the CPT-C protocol may have performed better than the WA condition, though the WA condition was still effective in reducing symptoms.

Modifications have been made to the original CPT format to adapt the protocol to various populations. CPT-C has been adapted in order to provide treatment through telehealth to rural populations [14]. Participants in this study were randomly assigned to either an in-person CPT-C group or a video teleconferencing CPT-C group. Both treatment groups received 12 90-min group sessions twice per week for 6 weeks. In the video teleconferencing group, there was the addition of an onsite observer with participants to facilitate faxing homework and to handle potential on-site emergent issues. Researchers found that there were no significant differences between the two treatment conditions and both conditions showed benefit from the treatment. While generalizability of this study may be limited by the small sample size, these results suggest that CPT-C can be effectively used over video teleconferencing.

CPT-C may be a preferable treatment option when participants are unwilling to complete a written trauma account, have limited memory of the traumatic event, or experience difficulty with writing. CPT-C has been examined among veterans with traumatic brain injuries (TBI) within a residential treatment setting and shown to significantly reduce PTSD symptoms [15]. A particularly noteworthy finding was that the reductions in PTSD symptoms were not only found for veterans with mild TBI but also found in veterans with a history of moderate-to-severe traumatic brain injury.

CPT has also been adapted to treat child abuse survivors (CPT-SA) [16]. CPT-SA was designed by integrating information processing, developmental, and self-trauma theories to appropriately address the fear processing, attachment, cognitions, and development associated with sexual abuse [17–20]. Changes from the original CPT protocol include focus on schema-congruent beliefs in addition to the inclusion of the schema-discrepant beliefs addressed in CPT.

Chard compared CPT-SA to a minimal attention wait-list control group [16]. The wait-list condition participants received a weekly phone call for the 17 weeks of the study, during which their emotional state was assessed. In the event they experienced a crisis, they were given supportive, nondirective, brief counseling, and if their symptoms warranted immediate therapeutic intervention, their study participation was discontinued. Participants in the wait-list condition were offered the opportunity to receive the treatment after the completion of the study.

Individuals in the CPT-SA treatment condition were provided 17 weeks of treatment. CPT-SA utilizes a combination of group and individual sessions and consists of 17 90-min group therapy sessions and 60-min individual therapy sessions for the first 9 weeks of the protocol and the 17th week. The individual sessions provide the opportunity for participants to process their abuse experiences. There is also the addition of a developmental session 2, giving individuals the opportunity to discuss their family of origin. During sessions 10 through 16, participants receive only group treatment to increase their independence from their individual therapist and build support with fellow group members. The group format facilitates practice of appropriate social interactions and testing of skills learned in the therapy. Supplemental session modules on assertiveness/communication, sexual intimacy, and social support were created for CPT-SA .

The results of the study were encouraging and suggest this modification is effective for treating survivors of sexual abuse. Participants in the CPT-SA treatment condition showed significant decreases on measures of PTSD, depression, and dissociation, and these improvements were maintained at one year following the completion of treatment. Further analyses of the data showed large effect sizes for change in the treatment group as compared to the minimal attention group.

CPT has also been adapted to meet needs of refugees, which is a unique population because many refugees have experienced multiple traumas. Schulz and her colleagues studied a sample of foreign-born refugees resettled in the United States in a naturalistic, community setting [21]. Participants were assigned either to receive CPT with the aid of an interpreter or to receive CPT with a therapist that spoke their native language. Both of the treatment conditions showed significant reduction in PTSD scores, while the group with a native language-speaking therapist had a greater decrease in scores. Treatment effects were robust to the effects of age, gender, and education level. In both treatment conditions, CPT was demonstrated to be a highly effective treatment for PTSD in refugee populations .

Although CPT is a treatment for PTSD, it targets underlying maladaptive cognitions, which are central to both PTSD and depression . There are very high rates of comorbid diagnoses of depression and PTSD. Orsillo and colleagues found that 55% of those who met criteria for PTSD also met criteria for depression [22]. Further support for this finding was found in the National Comorbidity Study that found that 47.9% of men and 48.5% of women had a PTSD diagnosis and a comorbid major depression diagnosis [23]. Taking into account this high rate of comorbidity, researchers of CPT have examined the impact of CPT on depression.

Resick and her colleagues found that in their study comparing CPT, PE, and a minimal attention wait list in a sample of female rape victims, both CPT and PE showed a significant decrease in participant’s self-reported depression at posttreatment and this improvement was maintained at follow-up [7]. In long-term follow-up data, Resick and her colleagues found that the impact of CPT and PE on depression was maintained up to 10 years after the completion of treatment [24]. Monson and her colleagues completed a study in which CPT was compared to a wait-list group and replicated the finding that CPT improves symptoms of depression [11]. Rizvi and her colleagues demonstrated that participants who had higher depression scores at the baseline had greater relative change in their PTSD severity over the course of treatment, suggesting that CPT is highly effective at treating depression [25]. CPT-C has also been shown to be effective in reducing depression in veterans with comorbid PTSD and traumatic brain injuries [15].

Researchers have examined the impact of CPT on several trauma-related symptoms , including guilt, affect dysregulation, anxiety, social problems, and physical health complaints [26–29]. In the Resick and colleagues [7] randomized controlled trial comparing CPT, PE, and minimal attention wait-list conditions, participants showed a differential response to the treatments on the subscales of the Trauma-Related Guilt Inventory [30], which include global guilt, hindsight bias, lack of justification, and wrongdoing. The aforementioned subscales are commonly challenged cognitive distortions and maladaptive thought patterns in CPT. While both CPT and PE groups showed decreases on all four subscales of the Trauma-Related Guilt Inventory , those in the CPT condition showed significantly lower scores on the hindsight bias and lack of justification subscales as compared to the PE and minimal attention ( MA) groups, and at the 9-month follow-up assessment, this pattern was maintained. For the intent-to-treat sample, CPT showed a large effect size for guilt cognitions, as compared to the medium effect size for PE. In the sample of those who completed treatment, CPT showed moderate-to-large effect sizes compared to PE at posttreatment and 9-month follow-up assessment. These findings suggest that CPT was more successful at reducing hindsight bias and lack of justification than PE.

The data from Resick and colleagues [7] was reexamined by Nishith, Nixon, and Resick to further understand the relationship between trauma-related guilt and depression [31]. Researchers found that data showed that CPT was effective at treating guilt in those with PTSD and PTSD and comorbid depression. They also found support for CPT being more effective in reducing certain kinds of guilt than PE.

Sobel and colleagues examined the impact of CPT on problematic cognitions [32]. Resick and Schnicke proposed that after a traumatic event, some individuals overaccommodate the new experience from the trauma and overgeneralize the experience [33]. Others assimilate, defined as incorporating new, unchanged information into a preexisting worldview or schema. In CPT, the goal is to cultivate accommodated or balanced views of the traumatic event. Sobel and colleagues found that when comparing statements describing the impact of the trauma on an individual pre- to posttreatment , there were significant decreases in the number and percentage of overaccommodated and assimilated statements [32]. They also found there was an increase in accommodated clauses, supporting the hypothesis that CPT is effective in reducing maladaptive thinking and developing more adaptive thinking.

In a veteran sample, Monson and her colleagues found that at posttreatment, individuals receiving CPT showed improvement on several measures of co-occurring symptoms [11]. Monson and her colleagues utilized the Spielberger State-Trait Anxiety Inventory [34] to measure general anxiety and assessed guilt distress with the Trauma-Related Guilt Inventory [30]. Researchers evaluated affect functioning with the Affect Control Scale [35], and the Toronto Alexithymia Scale-20 [36] was used to measure the ability to distinguish emotions from bodily sensation, ability to describe emotions, and having an externally oriented style of thinking. They also employed the Social Adjustment Scale [37] to assess functioning in several domains. Their findings were similar to those reported by Resick and her colleagues showing a decrease on the Trauma-Related Guilt Inventory at posttreatment for CPT group [7]. Monson and colleagues also observed significant improvements in general anxiety, affect functioning, and social adjustment at posttreatment for those receiving CPT.

In a residential PTSD treatment program for veterans, Owens, Chard, and Cox studied the change in maladaptive cognitions, anger expression, PTSD, and depression over the course of treatment [38]. They utilized the Cognitive Distortion Scale [39], Trauma-Related Guilt Inventory [30], Beck Depression Inventory-II [10], State-Trait Anger Expression Inventory [40], and the PTSD Checklist for DSM-IV-Military Version [41]. The Cognitive Distortion Scale was designed to measure cognitions of those in mental health treatment, and it includes five subscales: self-criticism, self-blame, helplessness, hopelessness, and preoccupation with danger [39]. It was found that maladaptive cognitions, anger expression, PTSD symptoms, and depression were all significantly lower at posttreatment. While these results are limited in generalizability because participants were in a residential program receiving additional interventions (e.g., psychoeducation groups), these results provide further support for previous findings that CPT is effective in reducing maladaptive cognitions.

Chronic health problems and generally poorer perception of physical health have also been associated with PTSD [42–45]. Galovski and her colleagues compared participants receiving CPT and PE on measures of health-related concerns [46]. Researchers used the Pennebaker Inventory of Limbic Languidness [47] to measure the frequency of occurrence of 54 physical symptoms and sensations, such as coughing, back pains, headaches, and nausea. It was found that those who completed CPT showed a significant improvement in reported physical health symptoms beyond those who completed PE. While none of the studies above measured sleep disturbance directly, research demonstrates that PTSD, depression, and other health conditions often negatively impact sleep and, by treating these disorders, sleep commonly improves as evidenced in the studies below.

As many as 70% of individuals diagnosed with post-traumatic stress disorder (PTSD) report sleep disturbances, including insomnia and nightmares [48]. Though some have speculated that evidence-based PTSD treatments and pharmacological interventions may not improve trauma-related sleep disturbances [49, 50], four studies have found that receiving cognitive processing therapy (CPT) was associated with improved sleep outcomes [46, 51–53].

In a direct comparison of CPT and prolonged exposure (PE) [46], Galovski and her colleagues (2009) assessed sleep and health impairment in 108 female victims of adult sexual assault. Sleep problems were measured with the Pittsburgh Sleep Quality Index (PSQI) [54], a self-report measure that captures seven domains, including subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, use of sleeping medications, and daytime dysfunction. Health issues were measured with the Pennebaker Inventory of Limbic Languidness [47]. Results indicated that while women in both treatment groups evidenced similar levels of sleep improvements, those in the CPT condition reported fewer perceived health problems compared to those in the PE condition (see Table 25.2) [46]. The authors hypothesized that the perception of health problems may be associated with a latent cognitive process that also functions as risk factor for development of PTSD, and therefore, a cognitive restructuring intervention such as CPT may better address perceptions of health problems compared to an exposure-based intervention like PE [46].