The treatment related publications of the last twenty years places a large amount of attention on determining the most useful psychological therapy for clients with a diagnosis of posttraumatic stress disorder, PTSD. The overall aim of this paper is to critically evaluate current cognitive models of PTSD and literature on the effectiveness of cognitive behavioural therapies to treat this disorder based on these models.
Definitions of PTSD
The 4th edition of the Diagnostic and Statistical Manual of Mental Disorders, DSM-IV (APA, 1994) defines ‘trauma’ as: ‘(a) The individual experienced, witnessed or was confronted with an event that involved actual or perceived threat to life or physical integrity; and (b) the individual’s emotional response to this event included horror, helplessness or intense fear’, Foa and Meadows (1997, p. 450).
The psychological symptoms connected with PTSD are categorised into three groups of symptoms in DSM-IV: The main characteristics include re-experiencing (in the form of flashbacks, intrusive thoughts, and distressing dreams), avoidance/numbing and heightened arousal, after the person is subjected to a traumatic incident. (Foa & Rothbaurn, 1992). The next group includes avoidance of stimuli trauma-reminding stimuli and symptoms of emotional numbing (Foa, Hearst-Ikeda, & Perry, 1995; Litz, 1993). The final symptom group includes heightened arousal e.g. hypervigilance, exaggerated startle response, difficulty sleeping and irritability (APA, 1994).
Current Government Guidelines on the treatment of PTSD
Determining effective and efficient treatments for PTSD has come to be seen as important due to the condition’s prevalence and the many techniques and interventions available. The National Institute for Clinical Excellence, NICE, reviewed the most robust outcome research and produced guidelines, to provide information and direction for the psychological management of PTSD in adult sufferers (NICE, 2005). The guidelines were developed from an independent, methodical, rigorous and multistage procedure of selecting, examining and assessing evidence for the successful treatment of PTSD. These guidelines conclude that individuals with PTSD should receive either trauma focused Cognitive Behavioural Therapy (TFCBT) or Eye Movement Desensitisation and Reprocessing (EMDR). However, a distinction is made between single incident trauma and more complex presentations, and the guidelines suggest increasing the total number of sessions accordingly. Although the guidelines appear helpful for the treatment of single incident PTSD, they are arguably not as informative for treatment approaches for a large group of individuals with ‘complex’ PTSD. This presents difficulties for the clinician and patient in deciding the most effective therapeutic options.
Cognitive Behavioural Therapy (CBT) is the most extensively studied therapy for individuals with PTSD (Foa & Meadows, 1997) and many studies support its efficacy in reducing symptom severity (e.g. Resick & Schnicke, 1992; Foa, Rothbaurn, 1992; Foa et al., 1995; Foa & Jaycox, 1996; Riggs, & Murdock, 1991; Richards, Lovell, & Marks, 1994; Thompson, Charlton, Kerry, Lee, & Turner, 1995). However, CBT for PTSD encompasses diverse techniques. These include exposure procedures, cognitive restructuring procedures, and combinations of both these techniques.
Exposure therapy is derived from the idea that imaginal exposure (IE) to the trauma or feared situation, leads to a decrease in symptoms. The theory argues enduring activation of traumatic memories result in processing of the emotional information, lessening of anxiety and assimilation of accurate memories (Foa et al., 1995). Much research has shown that treatment involving exposure therapy is effective in decreasing PTSD symptoms (e.g. Foa et al., 1999; Frueh, Turner, Beidel, Mirabella, & Jones, 1996; Keane, Fairbank, Cadell, & Zimmering, 1989).
Foa, Rothbaum, Riggs, and Murdoch (1991) investigated exposure therapy, stress inoculation (a type of Anxity Management Treatment, AMT), supportive counselling, and a non-treatment group in the management of rape-related PTSD. Clinical measures of symptoms and standardized psychometric tests were examined before and after treatment as well as at a three month follow-up. The stress inoculation intervention showed superior results to the counselling and non-treatment conditions at post-test. However, at the follow-up, the individuals participating in exposure therapy showed more improvements of PTSD symptoms than individuals in the other groups.
Research has investigated the efficiency of exposure therapy compared to different methods of treatment. For instance, exposure therapy and cognitive therapy were investigated by Tarrier et al. (1999) for the management of individuals with PTSD arising from various traumatic incidents. Although both approaches demonstrated a noteworthy decrease in PTSD symptoms that was still present at 6-months follow up there was no non-treatment control against which these two treatments could be evaluated.
Similarly, Foa et al. (1999) compared exposure therapy to AMT and then combined the two treatments. These three groups were compared to a non-treatment control group. All three of these treatments successfully decreased symptoms of rape-related PTSD and improved more than the non-treatment control group. However there was no significant variation among the treatment groups on outcome measures.
In a study that once again compared exposure therapy to cognitive therapy, Marks, Lovell, Noshirvani, Livanou, and Thrasher (1998) examined these two treatments alone and in combination in outpatients with PTSD secondary to a wide range of traumatic events. A relaxation therapy condition was employed as the comparison group. The three active treatment groups demonstrated significant reduction in symptoms compared to the relaxation sample. These intervention groups were not markedly different from on another on the main treatment outcome measures.
Several investigations have advanced the field of PTSD treatment, even though the methodology utilized in the outcome study limited the conclusions that could be drawn. Frank and Stewart (1983) reported the effects of systematic desensitization on women who had been raped and who developed significant psychological symptomatology. Compared to an untreated comparison group, those women treated with graduated exposure improved most on a range of anxiety and depression symptom measures.
Imaginal and in-vivo exposure was compared in a randomized study of survivors of varying traumatic events (Richards, Lovell, and Marks,1994). At the 12-month follow-up, patients reported consistent reductions in PTSD symptoms and improved social adjustment. This data further substantiates the efficiency of exposure treatment for some individuals, and also suggest that improvements in symptoms are also reflected in critical domains of life functioning. In conclusion, the existing data advocates the use of exposure therapy in the treatment of PTSD. In a previous review of this literature, Solomon, Gerrity, and Muff, (1992), (Sited in Shapiro, 1995) derived the same conclusion from data available at that time. Similar conclusions were drawn by Otto, Penava, Pollack, and Smoller (1996) in a more recent review of the literature.
In what may prove to be an important lesson for the treatment of individuals exposed to traumatic events, Foa, Hearst-Ikeda, and Perry (1995) investigated the effectiveness of a short-term intervention to prevent the development of chronic PTSD in females who had been recently raped. The program was based upon that which worked well in earlier trials with chronic PTSD. Exposure therapy figured prominently in the package of treatment and also included elements of education, breathing retraining, and cognitive restructuring. When individuals receiving the package were compared to a control group, this study found that at 2 months post-treatment only ten percent of the treatment sample met the diagnosis for PTSD, while seventy percent of the untreated comparison group did.
As information continues to grow on exposure therapy, there is a clear requirement for research to investigate combinations of psychological treatment, to utilize screening measures that consider occupational and social performance, and to access the outcome of interventions on co-morbid psychological difficulties. Unmistakably, the existing empirical research reveals the importance of extending the application of exposure approaches to PTSD patients. However future studies assessing the generalization of exposure therapy from laboratory trials to clinical settings would be particularly useful.
When exposure therapy has been compared to other forms of cognitive therapy, such as cognitive restructuring (see below), it has proved to be more successful in reducing PTSD. Tarrier et al., (1999) assigned 72 people with chronic PTSD to either a Cognitive Therapy (CT) group or an imaginal exposure (IE) therapy group, and concluded that there was no noteworthy differentiation between the two treatment conditions initially or at 12 months post treatment. Participants recruited were obtained from a sample of referrals to primary and secondary mental health services and voluntary services, indicating that they were representative of a genuine clinical sample. However, 50% of the sample remained above clinical significance for PTSD symptoms after treatment was completed, although this dropped to 25% at six-month follow-up. This lack of improvement may have been influenced by participant’s failure to attend sessions regularly. Furthermore, those who did not show improvement rated the treatment as ‘less convincing’ and were rated as ‘not as motivated’ by the clinician. Therefore, it is argued that motivation for therapy and regular attendance plays an important role in outcome of therapy regardless of treatment model. A further limitation of this study was that no control group was used and non-specific treatment factors and spontaneous remission could also account for the improvements in reported symptoms.
Cognitive restructuring is derived from the theory that discovering and altering catastrophic and inaccurate interpretation of the trauma leads to a decrease in symptoms. Some of the latest models have emphasised the significance of altering thinking distortions in the rehabilitation of individuals who have experienced trauma (Ehlers & Clarke, 2000).
Ehlers, Clark, Hackmann, McManus, and Fennell (2005) utilized cognitive therapy based on the cognitive model of PTSD (see figure 1. Ehlers & Clarke, 2000). From this model, the aim of therapy is to alter overly negative interpretations, amend the disturbance in autobiographical recollection and to eliminate the unhelpful behavioural and cognitive strategies (see figure 2, Ehlers et al., 2005). In a randomised controlled trial of twenty-eight participants diagnosed with PTSD. Fourteen participants were assigned at random to cognitive therapy treatment or a 13-week waiting-list condition. Those receiving cognitive therapy had 12 weekly treatment sessions, based on the Ehlers and Clarke (2000) model of trauma focused CBT. Participants completed self-report screenings of anxiety, mood and PTSD symptoms, and the Sheehan Disability Scale (APA, 2000). Measures were administered before and after treatment and at 6-months follow up. Findings revealed that cognitive therapy for PTSD was significantly better than a three month waiting-list group on symptoms of PTSD, disability and symptoms of anxiety and affect.
This study had no dropouts, which is a significant improvement on other studies, which yielded high dropout rates, (e.g. Tarrier et al., 1999). Participants displayed a positive change in cognitive appraisals. The Ehlers and Clarke (2000) model suggest that two additional paths of change; alteration in the autobiographical recollection of the trauma, and the discontinuation of maintenance behaviours and cognitive strategies are integral in reducing symptoms of PTSD. While the treatment incorporated these other aspects, these have not been measured systematically, so it is difficult to conclude whether clients experienced a change in these two areas.
Further analysis indicated that demographic, trauma and diagnostic variable did not predict intervention results, signifying that the approach is pertinent to a broad scope of individual who have experienced trauma. Conversely, the extent of discrepancy of trauma and small sample numbers suggests that this finding would not be present in a larger sample. Co-morbid depression and previous trauma history, which was present in over half the sample, did not negatively affect outcome.
Combinations of therapy
Resick and Schnicke (1992) have proffered a multidimensional behavioural treatment for females who have PTSD associated with sexual assault. This treatment, known as “cognitive processing therapy” (CPT), includes components of exposure therapy, AMT, and cognitive restructuring. The cognitive therapy element of CPT involves tackling central thinking distortions found among females who have been assaulted. These authors have developed interventions which particularly deal with concerns of trust, self-confidence, safety and intimacy in the lives of trauma victims. In a preliminary evaluation of CPT, the authors compared outcomes at pre-treatment, post-treatment, 3 months follow-up, and 6 months follow-up for an intervention group and a non-treatment group (no random assignment was used). On clinician ratings and psychometric inventories of PTSD, the individuals receiving CPT improved significantly. Impressively at the post-treatment assessment, none of the treated patients met criteria for PTSD.
In another study, Resick, Nishith, and Astin (2000) evaluated CPT and exposure therapy in the management of sexual assault-related PTSD. Both approaches proved successful in general and were more successful than a non-treatment control group. CPT did also seem to reduce comorbid symptoms of depression, as well as those of PTSD.
Combination therapy that incorporates a number of cognitive-behavioural techniques have the advantage of addressing various difficulties that individuals with PTSD may experience, in addition to integrating methods that have a considerable scientific evidence base in the clinical literature. An intervention incorporating exposure therapy, AMT, and cognitive restructuring as the main elements for treating PTSD was proposed by Keane, Fisher, Krinsley, and Niles (1994). This treatment utilizes six stages as a means of treating severe and chronic PTSD, it incorporates the following: (1) behavioural stabilization; (2) trauma psycho-education; (3) AMT; (4) trauma focus work; (5) relapse prevention skills; and (6) aftercare procedures.
Although this approach has clinical appeal, it wasn’t until psychologists Fecteau and Nicki (1999) examined such a package in a randomized clinical trial for PTSD resulting from automobile accidents that the impact of a combination package such as that proposed by Keane et al. (1994) was assessed. Their intervention consisted of psycho-education, relaxation, exposure, cognitive restructuring, and guided behavioural exercises. Patients were randomly assigned to the treatment group or non-treatment comparison group and received some 8-10 sessions of individualized treatment. The outcome of the treatment was effective as assessed by clinical ratings, self-report questionnaires, and lab-based psycho-physiological evaluation methods. Described by the authors as clinically and statistically significant, these treatment outcomes were sustained at the 6-month post treatment evaluation.
Bryant, Moulds, Guthrie, Dang, and Nixon (2003) studied the effects of IE alone or IE with CR in the treatment of PTSD. They hypothesised a CR and IE treatment combination would lead to significantly better decrease in PTSD symptoms than exposure on its own, which would be more beneficial than a supportive counselling condition. Fifty-eight civilian trauma victims, diagnosed with PTSD as measured by the Clinician Administered PTSD Scale, version II, CAPS-2, (Blake et al., 1995) were randomly allocated to one of the 3 conditions. Each participant received eight weekly 90-minute sessions of either IE, CR and IE or supportive counselling. Participants completed assessments at pre and post intervention and six months following. These measured PTSD symptoms and psychopathology. Forty-five participants completed treatment and analysis indicated that dropouts had higher scores for depression, avoidance and higher catastrophic cognitions than those who completed. Results indicated that participants receiving both IE and IE/CR had a siginifcantly better decrease in PTSD symptoms and anxiety than supportive counselling (SC).
The main revelation of this investigation was that treatment comprising of IE and CR leads to significantly better reductions in CAPS-II scores compared to treatment involving IE alone. Furthermore, those receiving IE/CR, but not IE on its own, gave accounts of less avoidance, depression and catastrophic thoughts than individuals in receipt SC. The findings from this research indicated that the combination of IE and CR are successful in decreasing symptoms of PTSD. It can be argued that the reasons why IE/CR may have been more effective than augmented treatments in the past (e.g. Foa et al., 1999) was that the research prudently controlled for the duration of time spent on every section of treatment. Furthermore, participants were instructed on CR before commencing IE so they understood the rationale behind the techniques prior to addressing the strong emotional components of IE. This may have increased their understanding and belief that it was a credible treatment approach.
The outcome that CR improved the benefits of IE treatment could have been a result of a number of likely mechanisms. IE and CR may consist of similar aspects, such as processing of emotional memories, amalgamation of corrective information and acomplishment of self-mastery (Marks, 2000). Combining the two approaches may give the patient more chances to achieve treatment gains. CR may have lead to greater decrease in symptoms as it explicitly attended to identifying and changing unhelpful thoughts that may add to the maintenance of PTSD and related difficulties (Ehlers & Clarke, 2000). Paunovic and Ost (2001), compared treatment outcome data for CBT and exposure therapy for sixteen refugees with PTSD. The authors excluded those who became too distressed in the initial interview, expressed ‘a lack of confidence’ in the therapist or were misusing alcohol or drugs. Results indicated there was no significant difference between participants completing CBT or exposure therapy, being similar to Tarrier et al’s (1999) findings.
Criticisms of Paunovic and Ost (2001)’s study are that participants did not use a self-report trauma measure, so although results are positive, there is no clear analysis of whether participants felt their trauma symptoms decreased as a result of the treatment. Further, it is not possible to generalise these findings to traumatised refugees in general, as this work is unique. Working with the use of an interpreter raises several ethical and sensitive issues, as the participant must be able to develop a therapeutic alliance with the therapist and trust the interpreter (Tribe, 2007). It could be argued that participants may have been experiencing a greater degree of trauma, not least because they had not yet learned the native language.
The most successful CBT treatments seem to be those that involve repeated exposure to the traumatic memory (Foa et al., 1991; Foa et al., 1999; Foa & Rothbaum, 1992) on cognitive restructuring of the interpretation of the traumatic event, (Ehlers & Clarke, 2000) or a combination of these approaches, (Resick & Schnicke, 1992). Importantly, studies have concluded that trauma focused CBT is more successful than supportive counselling (Blanchard et al., 2003; Bryant et al., 2003).
Whilst the studies reviewed have helpfully added to our understanding of PTSD there are numerous limitations of the applications of the findings. One in particular is an over-reliance on non-clinical samples of participants such that many claims of clinically effective therapy have been made from research with participants who were not within mental health systems, and despite having PTSD symptoms had not actively sought treatment.
In addition, dropout rates in studies are high, particularly for those studies that did not use a clinical sample. This might have skewed the evidence particularly with approaches that used exposure-based therapy. Furthermore, most of the studies reviewed screened out those individuals experiencing the greatest amount of distress, avoidance and co-morbidity.
Therefore results are biased towards those clients who were able to tolerate treatment and whose symptoms were not as chronic. Indeed, inclusion and exclusion criteria appear to have a great impact on outcome of treatment.
For example, studies with a strict inclusion criteria (e.g. no co-morbidity, substance misuse, self harm) appear to have significant improvements, whilst other studies i.e. Kubany et al., (2003), allowed participants to continue with other therapy while embarking on their therapy. This makes it methodologically difficult to ascertain exactly what has been effective in reducing PTSD symptoms. As inclusion and exclusion criteria are idiosyncratic across studies, it makes it difficult to draw general conclusions regarding treatment effectiveness with a clinical population across studies.
Studies often chose to focus therapy on identified groups, e.g. police officers. However, clients who experience PTSD do not form a homogeneous group and further, the symptoms experienced may be diverse even within a sample of individuals who have experienced the same trauma.
Treatment studies often do not control for other factors that may be important contributing factors in outcome such as the role of education, quality of the therapeutic relationship, therapeutic alliance and other nonspecific factors.
The literature was generally from American, British or European sources although clearly trauma is intercultural. This raises issues about how different cultures interpret ‘PTSD’, an essentially Western concept, and also whether the treatments advocated would be effective cross-culturally.
Previous research has strongly indicated that PTSD is not an appropriate term to use in non-western situations (Summerfield, 1997), hence therapeutic approaches need to account for this. It is not clear in the majority of studies when the participant experienced the trauma, and at what point therapy started. Frequently these characteristics are omitted from studies, therefore making it difficult to compare effectiveness of studies. It is essential to think about the types of individuals that have been represented in the research and to look at whether it is representative of those who seek treatment. Finally, very little has been reported on the impact of other difficulties an individual is experiencing as PTSD can have a broad ranging effect on an individuals quality of life and functioning and most often clients have more complex presentations. Only very few studies reviewed controlled for this variable (see Ehlers et al., 2005). This is an inherent difficulty when completing research with a trauma population as within research it is important to obtain a sample that have a similar degree of difficulties in order to assess treatment efficacy.
Several papers have evaluated different types of therapy according to particular groups. However, it appears that ‘one size’ does not fit all in relation to PTSID. In particular the issues of culture and gender are of importance (see Liebling & Ojiambo-Ochieng, 2000; Sheppard, 2000). Individual formulations of presenting problems and contexts, which informs therapy that is adapted to suit individual client’s needs, may in fact be more helpful. It remains important to consider individual differences and client choice when offering trauma therapy.
Trauma therapy outcome studies are limited by the fact that sufferers usually have other mental health problems alongside PTSD such as depression or social anxiety. Evaluation of effective treatment of trauma survivors therefore might need to go beyond medical diagnostic categories as most of the research excludes clients with co-morbid problems. A multifaceted intervention, based on clients’ own views, which addressed these other difficulties, could assist in decreasing relapse and greaten the long-lasting effectiveness of any PTSD intervention. As outlined in the methodological limitations section, much of the research reviewed has not used a genuine clinical sample, there are high dropout rates, widely variable inclusion and exclusion criteria, and the heterogeneity of PTSD has perhaps not yet been accounted for. It is therefore difficult to ascertain what is specifically helpful or effective within the treatment components. This seems to be the next area for consideration in research.
Further research into the optimal length of treatment and timing of therapy, the effect of co-morbidity and the differing effects of individual and group therapy approaches for traumatised clients are required. Further controlled research is needed to ascertain if the types of therapies reviewed can provide long term lasting effects in reducing PTSD symptomatology.
At present the scientific evidence is mainly restricted to the evaluation of short term, focused treatment approaches, and it would be helpful to have controlled studies on longer-term interventions for more complex cases of trauma. Further research would benefit from considering the clients views and experiences of therapy, this perspective was lacking in the literature reviewed. Service user and carer perspectives are beyond the scope of this review, however they have been highlighted as an important consideration within the NICE guidelines and therefore require further consideration in future research.
There appear to be at least three approaches with exceptional empirical evidence for treating PTSD; exposure therapy, cognitive therapy or a combination of these methods. These three interventions have empirical validation in well-controlled clinical trials, demonstrate strong treatment effect sizes, and seem to work well across varied populations of trauma sufferers. However future research to examine the efficacy of these methods in clinical environments is necessary.
There is much to be learned about the treatment of PTSD. It is certain there will be no simple answers for treating people who have experienced the most horrific events life offers. Undoubtedly, combinations of treatments as proposed by Keane et al. (1994) and Resick and Schnicke (1992) may prove to be the most powerful interventions.
PTSD research in this area is only in the earliest stages of its development.
Finally, an assumption about the uniformity of traumatic events has been made in the literature in general. Although it is reasonable to speculate that fundamental similarities exist among patients who have experienced diverse traumatic events and then develop PTSD, whether these patients will respond to clinical interventions in the same way is an empirical question that has yet to be addressed. Studies posing a question such as this would be a welcome addition to the clinical literature: Will people with PTSD resulting from combat, torture, genocide, and natural disasters all improve as well as those treated successfully following rape, motor vehicle accidents, and assaults? This is a crucial issue that requires additional scientific study in order to provide clinicians with the requisite evidence supporting the use of available techniques.
Research on the prevalence of exposure to traumatic events and the prevalence of PTSD has mainly been carried out in the United States. Yet there are fundamental errors in assuming that these prevalence rates apply even to other Western, developed countries. Studies that examine the prevalence of PTSD and other disorders internationally are clearly warranted. Implicit in this recommendation is the need to examine the extent to which current assessment instrumentation is culturally sensitive to the ways in which traumatic reactions are expressed internationally. Much work on this topic will be required before definitive conclusions regarding prevalence rates of PTSD internationally can be drawn.
Studies of the effectiveness of the psychological treatments across cultures and ethnic groups are also needed. What may be effective for Western populations may be inadequate or possibly even unacceptable treatment for people who reside in other areas of the world and who have different world views, beliefs, and perspectives. This issue will need to be more closely examined before we can draw definitive conclusions.
It is suggested that despite the type of treatment provided to individuals with trauma there is ultimately a necessity for a flexible, integrative approach to treatment in order to address the multifaceted and changing requirements of individual trauma survivors. A range of outcomes has been revealed with the types of treatments outlined in this review, it is uncertain which individuals will respond greatest to various treatment approaches. Nevertheless, what is important in determining the effectiveness of any psychological treatment of PTSD is that it is reliant upon forming and upholding a therapeutic alliance that is strong enough for the client to experience as safe and trusting for positive emotional modifications to take place.