The conceptualization of post-traumatic stress disorder (PTSD) as a conditioned fear (phobia) led experts to employ exposure therapy procedures that had been found efficacious with other types of phobic disorders to PTSD sufferers.1 The overlap of PTSD symptoms and those of generalized anxiety disorder led other experts to use anxiety management programs in the treatment of PTSD (eg, stress inoculation training). Emotional processing theory of PTSD has emphasized the important role of erroneous cognitions in the maintenance of PTSD.2,3 Specifically, Foa and Jaycox4 suggested that patients with PTSD have an exaggerated perception of the world as a dangerous place, and view themselves as extremely incapable of coping. They further suggested that any treatment that results in change in these erroneous cognitions would reduce the severity of PTSD symptoms. Similar conceptualizations have been advanced by other experts and have led to the development of cognitive therapy programs for PTSD.5
Most studies on treatment outcome for PTSD have utilized cognitivebehavioral therapy (CBT) programs. These programs include variants of exposure therapy, anxiety management, and cognitive therapy. Combinations of these interventions have also been investigated.6,7 More recently, eye movement desensitization and reprocessing (EMDR) has been employed for the treatment of PTSD, and a number of studies have explored its efficacy.8 In the treatment guidelines developed under the auspices of the International Society for Traumatic Stress Studies (ISTSS), exposure therapy emerged as the most empirically supported intervention for PTSD. In this article we focus on reviewing well-controlled studies that compared the efficacy of exposure therapy to that of other interventions. In comparing outcome across studies, we focus on percent change from baseline on the main PTSD measure calculated on completers whenever possible.
EXPOSURE THERAPY ALONE VERSUS OTHER TREATMENTS
The idea that therapy for trauma-related disturbances should include some form of exposure to the traumatic event has a long history in psychology and psychiatry.9 In its modern form, this idea is reflected in exposure therapy for PTSD. Exposure therapy for anxiety disorders comprises a set of techniques designed to help patients confront their feared objects, situations, memories, and images in a therapeutic manner. With PTSD, commonly the core components of exposure programs are imaginai exposure, (ie, repeated recounting of the traumatic memory), and in vivo exposure, (ie, repeated confrontation with trauma-related situations and objects that evoke excessive anxiety). Beyond this, programs may vary in the specifics. For example, the program developed by Keane and his colleagues10 for veterans with PTSD included relaxation training, and the program developed by Foa and colleagues,11 called prolonged exposure (PE)1 includes breathing training, psychoeducation, as well as discussion and processing following the imaginai exposure to the traumatic memory.
Several studies have investigated the effects of exposure therapy in veterans from the Vietnam War with PTSD. One study12 examined the efficacy of adding 6 to 14 sessions of imaginai exposure to the traumatic memories to standard psychosocial and pharmacological treatment. The group that received the imaginai exposure showed more reduction of symptoms than the group that received standard care (96% versus 1 5% reduction in nightmares, respectively). Keane et al.10 evaluated a program that included 14 to 16 sessions of implosive therapy, or flooding, combined with relaxation training. Again, the group that received treatment showed greater reduction in symptoms than the control group (40% reduction versus 33% increase in fear, 35% versus 0% reduction in re-experiencing symptoms, respectively). These studies indicate that exposure therapy is effective in reducing PTSD symptoms in Vietnam veterans, a population that is often considered to be treatment resistant.
Exposure therapy was also employed for PTSD following sexual and non-sexual assault. In the first study with rape victims,13 PE therapy was compared with stress inoculation training (SIT), supportive counseling (SC), and an untreated wait-list control in female assault victims with PTSD. Stress inoculation training,14 adopted by Veronen and KiIpatrick15 to treating post-rape psychological disturbances, is an anxiety management program that emerged from the view that pathologic anxiety stems from a deficit in skills required to cope with anxiety. Accordingly, it provides patients with management skills to help them reduce anxiety when it occurs. The SIT program used by Foa and colleagues in their studies was a modified version of the Veronen and Kilpatrick treatment; it included relaxation training, controlled breathing, positive imagery, cognitive restructuring, and distraction techniques. Supportive counseling focused on solving daily problems. Following 5 weeks of therapy (9 twice-weekly sessions), both PE and SIT were more effective than SC. Immediately after treatment, both SIT and PE patients improved on all three symptom clusters of PTSD, while patients receiving supportive counseling improved only on the arousal, but not on the avoidance or re-experiencing symptoms. At post-treatment, patients receiving PE evidenced an average of 40% reduction of PTSD symptoms versus 55% in patients receiving SIT, 26% in patients receiving SC, and 20% in the waitlist group. At a 3-month followup, PE reduced symptoms by an average of 60%, SIT, by 49%, and SC by 36%. Even better outcomes of PE emerged in later studies with female victims of assault with PTSD.
In a second study,7 Foa et al. compared PE, SIT, and their combination to a wait-list condition. At post-treatment, the average reduction of PTSD symptoms was 60% for PE, 57% for SIT, and 18% for wait list; at a 12-month follow-up, PE evidenced 66% reduction in PTSD severity versus 57% in SIT. In a third study,16 Foa et al. compared PE to the combination of PE and cognitive restructuring (CR), a variant of cognitive therapy. Prolonged exposure therapy alone evidenced 76% PTSD symptom reduction at post-treatment and 79% at the last available follow-up (3 to 12 months). Thus, in treatment studies conducted by Foa and colleagues, after 9 sessions of PE the average reduction of PTSD symptoms at follow-up ranged between 50% and 78%, with better outcome evident in the later studies. While SIT was also found quite effective, at follow-ups it was consistently, although not significantly, less effective than PE.
The efficacy of PE was also established in Resick and colleagues* study17 comparing PE with cognitive processing therapy (CPT) for rape victims with PTSD. Cognitive processing therapy addresses maladaptive cognitions relevant to rape with a focus on five themes: safety, trust, power, esteem, and intimacy. The program also includes an exposure component in the form of writing a detailed account of the traumatic memory and reading it back to the therapist during two sessions. Twelve weekly sessions of CPT were highly and equally effective to nine sessions of PE in ameliorating PTSD. Both CPT and PE were more effective in reducing PTSD symptoms than a minimal attention wait-list control group and treatment gains were maintained at follow-up. At post treatment, CPT and PE patients evidenced an average of 72% and 67% reduction in PTSD symptoms, respectively. These results were maintained at the 9-month follow-up: the average symptom reduction was 60% for CPT and 68% for PE. Thus, the magnitude of symptom reduction as well as the pattern of results is consistent with Foa and colleagues' data. Utilizing a variant of PE in which 5 sessions of imaginai exposure were followed by 5 sessions of in vivo exposure, Marks et al.6 found similar PTSD reduction (81% at follow-up).
A different exposure program was adopted by Tamer et al.18 to compare exposure therapy with cognitive therapy in victims of mixed traumas with PTSD. Unlike the PE program described above, exposure in this study included imaginai exposure (IE) without in vivo exposure. Both therapies produced significant but relatively modest improvements in PTSD symptoms, with no significant differences emerging between the two treatments; the results were maintained at a 12-month follow-up.19 At post-treatment, PTSD symptom severity was decreased on the average by 32% after IE and by 35% after cognitive therapy and these reductions were maintained over 12 months: 37% in the IE group and 32% in the cognitive therapy group. It should be noted that the effects of both therapies in this study were much lower than the average 60% to 78 % reductions for PE and CPT.6,7,17 The omission of in vivo exposure may explain the inferior outcome found for the IE group compared to PE programs20 Indeed Richards et al.21 found that in vivo exposure has therapeutic effects beyond that of imaginai exposure.
Despite the repeated findings affirming the high efficacy of PE, there has been reluctance by therapists to implement PE alone with PTSD patients because of the belief that many patients would find PE difficult to tolerate.22 This view has led experts to advocate the addition of supplementary procedures to PE with the aim at offsetting PE-related stress.
THE EFFICACY OF COMBINED PROGRAMS THAT INCLUDE EXPOSURE THERAPY
As discussed above, Foa et al.7 compared the efficacy of PE alone and SIT alone to that of the combination (pe/SIT). Following a 5-week therapy (9 twice-weekly sessions), PTSD symptorn severity decreased by an average of 60% after PE and 55% after PE/SIT; at a 12- months follow-up, PE evidenced 64% symptom reduction versus 59% in the PE/SIT group. This PE/SIT program has been adopted in several studies. In one study with victims of motor vehicle accidents with PTSD, PE/SIT was compared with supportive counseling and a wait-list control group.23 At post treatment and at follow-up, PE/SIT was more effective than supportive counseling, which, in turn, was more effective than the wait-list control group. Patients who received PE/SIT showed an average of 65% reduction in PTSD symptoms versus 38% in those who received SC and 18% in those who did not receive treatment (wait-list control); at a 3-month follow-up, symptom reduction in PE/SIT was 68% and in supportive counseling, 39%.
Eye movement desensitization and reprocessing consists of a form of exposure accompanied by saccadic eye movements.24 In EMDR, the therapist asks the patient to visualize images about the trauma while inducing eye movements by asking the patient to track rapid side-to-side movement of the therapist's finger. A cognitive therapy component is also included in which patients are asked to replace negative thoughts with positive ones. Thus, EMDR may be conceptualized as a special version of a combined treatment. Several studies have been conducted to evaluate the efficacy of EMDR and the role of the eye movements, although most have not been well controlled,8 Several reviews suggest that in comparison to no treatment or nonspecific therapies for PTSD, EMDR is successful. However, a meta-analytical study has found EMDR less effective than exposure therapy programs.25
Devilly and Spence26 compared EMDR with a combination of PE and SIT modified from the Foa et al. study.13 At post-treatment, the modified PE/S1T reduced PTSD symptom severity by 63% versus 46% in the EMDR condition. At 3-months follow-up, average symptom reduction was 61% for PE/SIT and only 12% in EMDR. A similar pattern of results was found by Rothbaum and colleagues.27
CAN THE EFFECT OF EXPOSURE THERAPY BE AUGMENTED BY THE ADDITION OF OTHER CBT TECHNIQUES?
While the studies discussed above attest to the high efficacy of exposure therapy for the majority of PTSD patients, there is certainly room for improvement: many patients remain somewhat symptomatic and some do not benefit from treatment. Five studies examined whether the addition of other CBT procedures to exposure therapy augments its efficacy: only one study found an augmentation effect. As noted above, several studies used a combination of PE/SIT to evaluate the efficacy of CBT with PTSD sufferers, but only the Foa et al.7 study described above examined the augmentation of PE by SIT. Contrary to expectation, ??/SIT did not fair better than either treatment alone. Foa et al. suggested that the combined treatment could have placed considerable demands on the patients and that such demands may have compromised possible therapeutic enhancement of the combined therapy. To correct for this possible overload and in a further exploration of ways to augment PE, Foa et al. conducted a study,16 mentioned above, with female victims of sexual and nonsexual assault with PTSD examining the effects of PE augmented by CR, a component of cognitive therapy that focuses on teaching patients to replace negative, dysfunctional thoughts and beliefs with rational, realistic ones. This combined treatment (??/CR) was compared to PE alone and to a wait-list control group. Patients who failed to reach 70% improvement in PTSD symptoms following the initial 9session course of treatment were given three additional sessions. Preliminary analyses indicate that the two programs were highly effective in reducing PTSD symptoms compared to the wait-list control group. Patients in the PE alone group showed a mean PTSD symptom reduction of 78% versus 62% in the ??/CR group. Also, PE was more efficient when delivered alone than when combined with CR. More than half (51%) of the group that received PE achieved criterion for responder (70% improvement) in the core nine sessions, whereas 70% of patients in the PE + CR group did not reach this criteria in nine sessions. At a 1-year follow-up, PTSD symptoms were reduced by 79% in the PE alone group versus 70% in the PE/CR group. Thus, PE alone was found not only as effective as PE/CR, but also more efficient.
Marks et al.6 utilized a variant of exposure in which five sessions of imaginai exposure were followed by five sessions of in vivo exposure and compared this treatment with CR, their combination (PFVCR), and a relaxation control in victims of mixed traumas with PTSD. Exposure therapy and CR, singly or combined, improved symptoms of PTSD markedly, but the combined treatment was not more effective than the single treatments. At post-treatment, no group differences emerged. On the average, PTSD severity was decreased by 42% in PE, 50% in CR, 35% in PFVCR, and 37% in relaxation. At follow-up, the groups that received PE alone or PE in combination with CR seemed to show further improvement, whereas the CR group did not. Six months after treatment, the PE group evidenced an 81% decrease in symptoms, the CR, a 53% reduction, and PE/CR a 74% reduction. These results seem to suggest that at follow-up, the addition of PE to CR augments the outcome of CR, while the addition of CR to PE did not increase PE efficacy.
A failure to find augmentation effects of CR emerges from a study of Swedish refugees with PTSD comparing PE combined with CR to PE alone, both delivered in 16 to 20 weekly sessions.28 On average, at post-treatment, PE resulted in a 53% reduction in PTSD symptoms versus a 48% reduction for the combined group. This pattern of results was maintained at the 6-month follow-up, with the PE only group and the combined group showing 49% and 44% reduction in symptoms, respectively. Similar patterns were also observed for anxiety and depression. While die magnitude of PE alone or combined with CR was somewhat lower in this study (perhaps because of the unique population) than in previous studies, again, the combined group did not afford advantage over PE alone. The only study that found an augmentation effect for exposure therapy was conducted by Bryant et al.,29 who compared the efficacy of eight sessions of imaginai without in vivo exposure with a combination of their exposure therapy and cognitive therapy, and supportive counseling. Patients were victims of a variety of traumas. Both IE and IE/cognitive therapy were found superior to supportive counseling on most measures, but IE/cognitive therapy was superior to IE. At post-treatment, the average reduction of PTSD symptoms was 48% for IE, 67% for IE/cognitive therapy, and 22% for supportive counseling; at last followup the average reductions were: 46% for IE, 74% for IE/cognitive therapy, and 17% for supportive counseling. Interestingly, the magnitude of symptom reduction in the IE only group was similar to that reported by Tarrier et al. and, in both studies the magnitude is considerably lower than the 60% to 80% reduction reported for programs that used both imaginai and in vivo exposure. Thus, the augmentation effects in the Bryant et al. study were not achieved by increasing the efficacy of exposure therapy beyond that found in previous studies, but rather by using a treatment that yielded inferior outcome and augmenting it to a level ofthat found when exposure therapy included both the in vivo and imaginai components.
The studies discussed above have ? demonstrated that exposure therapy is highly effective in ameliorating PTSD and related symptoms. Moreover, at follow-up, gains are maintained and sometimes increase, resulting in an average of 60% to 80% reduction in PTSD symptom severity. Attempts to augment the efficacy of exposure therapy that includes both imaginai and in vivo exposure by adding other treatments such as SIT or cognitive therapy/CR were unsuccessful as no additional therapeutic benefit to exposure alone was observed. However, when exposure therapy is diluted by eliminating in vivo exposure, one of the two crucial components of the treatment, treatment effects are diminished, thus allowing for an augmentation effect to emerge. Some experts suggested that the advantage of treatments that combined PE with other procedures such as cognitive therapy or SIT is not in enhancing outcome but by increasing patients' retention in treatment.30 This hypothesis has not been supported empirically as dropout rates in PE do not differ from those in combination treatments. (Hembree EA, Foa EB, Dorfan NM, Street G. Unpublished data, 2002.)
Why do augmentation strategies fail to benefit PE? One possible explanation is that the combined therapies in the augmentation studies have been delivered in the same number and length of sessions as the single treatments, and thus patients in these treatments were deprived of the full dose of the single treatments. In the Foa et al. study7 for example, patients who received combination therapy did not receive as much exposure as those in the PE-only group or as much SIT as those in the SIT-only group. Similarly, in the study by Marks et al.,6 patients in the ??/CR group may have been deprived of sufficient PE or CR. However, in the Marks et al. study, CR seemed to have benefited from the addition of PE, suggesting that the time factor by itself is not sufficient to explain why PE failed to benefit from the addition of CR.
What then can account for the failure of SIT and cognitive therapy to augment treatment that includes both imaginai and in vivo exposure? Modification of cognitions is the main goal of cognitive restructuring, where dysfunctional beliefs thought to underlie PTSD are formally addressed through helping the patient identify the dysfunctional beliefs, examine whether or not these beliefs accurately reflect reality, and replace mistaken or dysfunctional beliefs with more realistic, helpful ideas. l7;s Although PE does not involve formal discussions of the patients' beliefs about the world and themselves, it has been thought to decrease pathological anxiety via modification of the cognitions that underlie the target disorder.3 With PTSD, PE is thought to modify cognitions in two ways.4 First, repeated reliving of the trauma promotes the realization that the trauma was a distinct event rather than a prototype of the world as a whole, and this realization serves to increase discrimination between danger and safety signals. Second, the successful processing of the trauma leads to a reduction in PTSD symptoms and this symptom reduction promotes positive self-perception.
Thus, both cognitive therapy and exposure therapy aim at reducing symptoms via correcting the erroneous cognitions associated with PTSD. While SIT directly addresses dysfunctional cognitions in only one component, the successful acquisition of skills that help patients cope with their fear and anxiety is likely to foster a more positive perception of oneself as a person successful at coping which, in turn, reduces threat appraisals about the world. The corrective experiences during imaginai and in vivo exposure together with the informal discussions about these experiences that always take place during responsible administration of PE, can be extremely potent in modifying dysfunctional cognitions, not leaving much room for additional modification via other procedures. This explanation of the repeated failure to augment PE is consistent with recent findings demonstrating that negative cognitions about oneself and the world decreased after both PE and PFVcognitive therapy and that PE/cognitive therapy did not evidence superior ability to modify cognitions over PE alone. (Foa EB, Rauch SAM. Unpublished data, 2002.) Similar findings were reported for social phobia31 and for panic disorder:32 In both studies, treatment by exposure therapy alone modified the negative cognitions associated with the target disorder more than cognitive therapy alone, and as much as the combined in the second study.
In the 1960s, imaginai exposure was prominent in cognitive behavior therapy of anxiety disorders.33 In the '70s, following findings demonstrating the superiority of in vivo over imaginai exposure, especially with specific phobies,34 many clinicians and researchers abandoned the use of imaginai exposure for anxiety disorders in favor of in vivo exposure. Because of the critical position of the traumatic memories in the psychopathology of PTSD, imaginai exposure has received a prominent place in exposure therapy for this disorder. However, as suggested by Foa and Jaycox,4 the use of in vivo exposure remains crucial for the success of PE as it uniquely corrects the exaggerated probability of threat held by PTSD patients, which motivates extensive avoidance of realistically safe situations. Indeed, elimination of in vivo exposure in the Tarrier et al.18 and Bryant et aL29 studies decreased treatment efficacy.
In this article, we chose to focus on discussing studies that aimed at augmenting PE with other cognitive behavioral procedures. Of the existing treatment programs, exposure therapy has the most empirical support for its high efficacy and efficiency in different populations of trauma victims with PTSD. More studies are needed to examine SIT with populations other than female survivors of assault, although SlT is clearly helpful in this population. Cognitive therapy is promising but more controlled studies are needed before its efficacy with different victim populations can be ascertained. Notwithstanding the failure to augment PE with other CBT treatment, some patients who receive this treatment fail to show sufficient gains. No studies to date have examined the relative efficacy of medication and CBT and whether the combination of the two will augment the efficacy of each. This may be the next avenue for exploring how to augment the efficacy of existing treatments.
1. Keane TM, Zimmerling RT, Caddell JM. A behavioral formulation of post-traumatic stress disorder in Vietnam veterans. Behavior Therapist. 1985;8:9-12.
2. Foa EB, Steketee G, Rothbaum B. Behavioral / cognitive conceptualizations of posttraumatic stress disorder. Behavior Therapy. 1989;20:155-176.
3. Foa EB, Kozak MJ. Emotional processing of fear: exposure to corrective information. Psychol Bull. 1986;99:20-35.
4. Foa EB, Jaycox LH. Cognitivebehavioral theory and treatment of post-traumatic stress disorder. In: Spiegel DS, ed. Efficacy and CostEffectiveness of Psychotherapy. Washington, DC: American Psychiatric Press; 1999:23-61.
5. Ehlers AE, Clark D. A cognitive model of persistent posttraumatic stress disorder. Behav Res Ther. 2000;38(4):319-345.
6. Marks I, Lovell K, Noshirvani H, et al. Treatment of posttraumatic stress disorder by exposure and /or cognitive restructuring: a controlled study. Arch Gen Psychiatry. 1998;55:317-325.
7. Foa EB, Dancu CV, Hembree EA, Jaycox LH, Meadows EA, Street GP. A comparison of exposure therapy, stress inoculation training, and their combination for reducing posttraumatic stress disorder in female assault victims. J Consult Clin Psychol. 1999;67:194-200.
8. Foa EB, Meadows EA. Psychosocial treatments for posttraumatic stress disorder: a critical review. Annu Rev Psychol. 1997;48:449-480.
9. Rivers WHR. Repression and Suppression. In: Miller HC, ed. Functional Nerve Disease: An Epitome oj War Experience for the Practitioner London: Henry Frowde [and] Hodder & Stoughton; 1920:88-98.
10. Keane TM, Fairbank JA, Caddell JM, et al. Implosive (flooding) therapy reduces symptoms of PTSD in Vietnam combat veterans. Behavioi Therapy. 1989;20:245-260.
11. Foa EB, Rothbaum BO. Treating iht Trauma of Rape. New York, NY Guilford; 1998.
12. Cooper NA, Cium GA. Imaginai flooding as a supplementary treatment for PTSD in combat veterans: a controlled study. Behavior Therapy. 1989; 20:381-391.
13. Foa EB, Rothbaum BO, Riggs D, et al. Treatment of post-traumati< stress disorder in rape victims: fi comparison between cognitivi behavioral procedures and coun seling. / Consult Clin Psychol 1991;59:715-723.
14. Meichenbaum D. Cognitive Behavioi Modification. Morristown, NJ: Gen eral Learning Press; 1974.
15. Veronen LJ, Kilpatrick DG. Stars,- Inoculation Training for Victims o Rape: Efficacy and Differential Find ings. Presented at: 16th annua meeting of the Association fo Advancement of Behavior Therapy November, 1982; Los Angeles, Calif.
16. Foa EB. Successful dissemination of prolonged exposure to a community based clinic. In: Bryant R, chair, Cognitive Behavior Therapy for PTSD. Symposium presented at the Meeting of the World Congress of Behavioral and Cognitive Therapies; July, 2001; Vancouver, BC, Canada.
17. Reside PA, Nisthith P, Astin M. A controlled trial comparing cognitive processing therapy and prolonged exposure: preliminary findings. / Consult Clin Psychol. In press.
18. Tamer N, Pilgrim H, Sommerfield C, et al. A randomized trial of cognitive therapy and imaginai exposure in the treatment of chronic posttraumatic stress disorder. / Consult Clin Psychol. 1999;67:13-18.
19. Tarrier N, Sommerfield C, Pilgrim H, Humphreys L. Cognitive therapy or imaginai exposure in the treatment of posttraumatic stress disorder. Br J Psychiatry. 1999;175:571-575.
20. Devilly G), Foa EB. The investigation of exposure and cognitive therapy: comment on Tarrier et al. (1999). / Consult Clin Psycho!. 2001;69(1):114-U6.
21. Richards DA, Lovell K, Marks IM. Posttraumatic stress disorder evaluation of a behavioral treatment program. / Traumatic Stress. 1994;7:669-680.
22. Zayfert C, Black C. Implementation of empirically supported treatment for PTSD: obstacles and innovations. Behavior Therapist. 2000;23:161-168.
23. Blanchard EB, Hickling EJ, Devineni T, et al. A controlled evaluation of cognitive behavioral therapy for posttraumatic stress in motor vehicle accident survivors. Behav Res Ther. In press.
24. Shapiro F. Eye Movement Desensitization and Reprocessing: Basic Principles, Protocols, and Procedures. New York, NY: Guilford; 1995.
25. Davidson PR, Parker KCH. Eye movement desensitization and reprocessing (EMDR): a meta-analysis. / Consult Clin Psychol. 2001;69:305-319.
26. Devilly GJ, Spence SH. The relative efficacy and treatment distress of EMDR and a cognitive-behavior trauma protocol in the amelioration of posttraumatic stress disorder. / Anxiety Disord. 1999;13:131-157.
27. Rothbaum BO, Astin M. Prolonged exposure versus EMDR for PTSD rape victims. In: Resick PA, chair, Three Clinical Trials for the Treatment of PTSD: Outcome and Dissemination. Symposium presented at the 35th Annual Convention for the Association for Advancement of Behavior Therapy; November, 2001; Philadelphia, PA.
28. Paunovic N, Ost L. Cognitive-behavior therapy vs exposure therapy in treatment of PTSD in refugees. Behav Res Ther. 200139:1183-1197.
29. Bryant RA, Moulds ML, Guthrie RM, Dang ST, Nixon RDV. Prolonged exposure alone and prolonged exposure with cognitive restructuring in treatment of posttraumatic stress disorder. / Consult CUn Psychol In press.
30. Bryant RA. CBT in the treatment of acute stress disorder. In: Keane TM, chair, State of the Art Intervention to Reduce and Prevent Trauma Symptoms. Symposium presented at the American Psychological Association Annual Convention; August 22, 2002; Chicago, IL.
31. Hope DA, Heimberg RG, Bruch MA. Dismantling cognitive-behavioral group therapy for soda! phobia. Behav Res Ther. 199533:637-650.
32. Williams SL, Falbo J. Cognitive and performance-based treatments for panic attacks in people with varying degrees of agoraphobic disability. Behav Res Ther. 1996;34:253-264.
33. Wolpe J. The Practice of Behavior Therapy. New York, NY: Pergamon; 1969.
34. Mathews AM. Fear-reduction research and clinical phobias. Psychol Bull. 1978;85:390-404.