Exposure Therapy for PTSD

Posttraumatic Stress Disorder (PTSD) was introduced in the Diagnostic and Statistical Manual (DSM) of mental disorders as a diagnostic category in 1980 (APA 1980). Since then, there has been an increased emphasis on the study of its psychopathology and treatment given the significant personal distress and interpersonal/occupational impairment associated with this condition.

PTSD is concerned with a natural human condition, reaction to adversity (Herbert & Sageman, 2004). Human beings have long tried to cope with adversity using a multitude of strategies that are usually effective. History is filled with examples of the resilience of humans and their capacity to overcome severe traumas such as war, terrorist attacks, and physical assault.

PTSD occurs when the strategies to overcome traumas do not work. In that case, a typical reaction is increased arousal, avoidance of reminders of the trauma in many forms (situations, emotions, activities, etc.), and reexperiencing symptoms in several forms (flashbacks, nightmares, repetitive thoughts or images, etc.). These three clusters of symptoms constitute the core of PTSD that can become a complex and chronic psychological problem.

At the current time, evidence-based approaches for the treatment of this condition are available. Cognitive behavior therapy (CBT) programs have been demonstrated to be effective in the treatment of this problem. In fact, exposure therapy is considered the first-line treatment for PTSD, given the amount of empirical evidence that has been generated in support of its clinical efficacy (i.e., Foa, Rothbaum, & Furr, 2003).

Exposure therapy is based on the notion that people are able to adjust to distressing, but not dangerous, stimuli through repeated confrontation with these situations. By repeatedly confronting the anxiety-provoking situation in a safe, therapeutic environment, unrealistic cognitions are disconfirmed and the situations cease to arouse excessive distress. Through repeated practice, exposure therapy helps the person generate new and adaptable patterns of thinking and feeling. One process involved in the efficacy of exposure is emotional processing. Foa and Kozak (1986) used this concept to explain fear reduction during exposure. Emotional processing theory proposes that anxiety disorders reflect fear structures that contain pathological and unrealistic associations among the elements that constitute the experience (physiological, cognitive, and behavioral). Foa and Kozak suggested that exposure to feared stimuli allow: (a) the activation of the fear structure and (b) the presentation of corrective information incompatible with the pathological elements of the fear structure. Foa and McNally (1996) suggested that exposure therapy helps to form a new structure that contains more realistic associations among the elements. This process is especially relevant in the case of PTSD.

Exposure may occur through imagining the anxiety-arousing stimuli or in vivo where the person confronts the real life situation, object, or person that arouses the anxiety. The therapeutic strategy involves identification of the stimulus cues that activate fears associated with the traumatic events. The individual is then exposed to those cues through prolonged and repeated imaginal and in vivo exposure. With the support of the therapist, the individual learns how to self-manage the unwanted responses in the presence of a variety of stimulus cues.

Exposure-based techniques provide participants with opportunities to learn to control their own responses when confronted with stimuli related to the traumatic experience. The treatment program for PTSD with the most empirical support is Prolonged Exposure (PE), developed by Foa and Rothbaum (1998), which involves imaginal exposure to the traumatic experience. The aim of this intervention is to evoke the stressful event and to work on processing it in an adaptive way. Exposure may also involve real life situations, objects, or people that arouse the anxiety. The individual can also receive training in self-regulation skills like breathing, training, and reframing interpretations of events.

Limitations of Exposure Therapy for PTSD

Despite these encouraging findings, exposure appears to be under-utilized in clinical practice. Becker et al. (2004) found that only a small minority of a sample of psychologists used exposure to treat PTSD. Although around half of the sample reported being familiar with imaginal exposure (IE), only 17 % used it to treat PTSD. One of the main reasons for not using IE was lack of training and experience with PTSD. However, of those who were trained and had experience in treating PTSD, less than 50 % used it to treat at least half of their PTSD patients. When asking therapists about the barriers to using IE, they indicated contraindications not empirically based, like a worsening in symptoms or an increased desire to drop out of therapy. These views were independent of training, familiarity, or theoretical orientation. Becker et al. expressed their concern with these findings given that as they stated “many patients who could benefit from exposure are inappropriately being excluded based on clinicians’ beliefs that IE is associated with an extensive list of contraindications” (p. 289). The conclusion to this study is that IE has an important problem concerning dissemination among clinicians.

Empirical evidence does not support such contraindications. Hembree et al. (2003) offered data about the dropout rate of exposure therapy for PTSD. These authors reviewed 25 controlled studies exploring the efficacy of CBT for PTSD. The results did not support the hypothesis that dropout rates for exposure therapy will be higher than from other treatments that do not include the more direct confrontation of trauma memory that is characteristic of IE (Cognitive Restructuring, Stress Inoculation Training, and Eye Movement Desensitization and Reprocessing). The dropout rate for exposure therapy was 20.5 %, similar to the dropout rates of the other forms of CBT for PTSD and similar to the dropout rates of exposure therapy for other diagnostic groups.

Another concern about exposure therapy is symptom exacerbation. Foa, Zoellner, Feeny, Hembree, and Alvarez-Conrad (2002) explored symptom exacerbation in a sample of women diagnosed with PTSD and treated with exposure therapy. They found that only a minority of patients (11 %) showed an exacerbation of PTSD symptoms that was temporary. As well, such exacerbation was not related to dropout or treatment response. Another barrier for dissemination of exposure therapy for PTSD could be patients’ preferences. Becker et al. (2004) conducted a survey with an analog sample with varying degrees of trauma history (7 % met self-reported criteria of PTSD). They were asked to imagine experiencing a traumatic event, developing PTSD symptoms, and seeking treatment. They evaluated seven descriptions of different treatments (Exposure, CBT, Eye Movement Desensitization and Reprocessing, Psychodynamic, Thought-field therapy, Sertraline, My Therapy Buddy) and rated their most and least preferred treatment. Most participants chose exposure therapy and CBTs the most preferred treatment, which contradicts the general view that exposure therapy will be rejected by PTSD patients. The preference rates were similar in participants meeting PTSD criteria, although it is important to obtain results from clinical samples to strengthen these results. These authors conclude that the problem of underutilization of exposure therapy may be due to more therapists’ factors than to patients’ preferences. These findings support that exposure therapy is not only an efficacious approach to treat PTSD, but also more tolerable than many clinicians think.

Alternatively, it is important to take into consideration the concerns raised by clinicians. An interesting study conducted by Zayfert et al. (2005) points out the differences in dropout rates in randomized clinical trials similar to those reviewed by Hembree et al. (2003) and in naturalistic clinical settings. In this setting they found that the completion rate of CBT (28 %) was markedly lower than rates reported in randomized trials (60 %). When studying the relationship between IE and dropout they found that most dropouts occurred before starting IE and that initiating IE was associated with greater likelihood of completion. Avoidance and depression were the unique predictors of non-completion. These findings indicate that individuals who are more avoidant and depressed are more likely to show reluctance to begin IE or show behaviors that inhibit clinicians from initiating IE. The problem is not the efficacy of IE, given that once the patient starts IE they are more prone to complete the treatment. Zayfert et al. concluded that it is important to explore the factors affecting treatment engagement and develop means to help clinicians to be able to better apply IE.

Avoidance of the feared stimuli is a central diagnostic feature of anxiety disorders and PTSD. Thus, the need to confront the trauma in therapy can present a significant challenge for these patients. Some patients are able to think about their trauma, but are emotionally detached from the experience. The lack of emotional engagement can hinder anxiety reduction, resulting in poor treatment outcomes Jaycox, Foa, and Morral (1998). Potential negative effects on treatment response can also occur as a result of the patient’s inability to imagine.

Finally, we would like to mention the study by Bradley, Greene, Russ, Dutra, and Westen (2005) who conducted a meta-analysis of 26 efficacy studies of psychotherapy for PTSD and found that 56 % of those following a psychological treatment and 67 % of completers did not meet criteria for PTSD at posttreatment. Although these findings are very encouraging, pointing out that we have at our disposal good psychological treatments for PTSD (exposure therapy being the most supported by the scientific evidence), there is still room for improvement in order to reach and benefit a larger number of PTSD patients.

Emerging Treatments for PTSD

Based on the scientific literature, exposure therapy is considered to be the gold standard treatment for PTSD. However, despite the impressive efficacy data of this approach there are still limitations and not all people who need treatment could benefit.

With this in mind, several approaches have been recently designed and tested with the aim of improving psychological treatments for PTSD. Cukor, Spitalnick, Difede, Rizzo, and Rothbaum (2009) reviewed these emerging treatments for PTSD. They divided the different therapies in the following categories: (a) Social and family-based treatments (couple and family therapy and interpersonal psychotherapy); (b) behavioral treatments (behavioral activation, trauma management therapy, interoceptive exposure, mindfulness, and yoga and acupuncture); (c) imagery-based treatments (imagery rescripting and imagery rehearsal therapy); (d) therapies focusing on distress tolerance (dialectical behavior therapy, DBT, and acceptance and commitment therapy, ACT); (e) power therapy (thought field therapy, trauma incident reduction, and Visio kinesthetic disassociation); and finally (f) technological-based treatments (Internet and computer-based treatment and virtual reality).

After performing this review the authors concluded that there is a growing effort by clinicians and researchers to develop alternative treatment approaches. However, sufficient evidence to draw conclusions about their efficacy has not been generated thus far. It seems that some of these approaches can help to augment an already well-established treatment such as IE by addressing specific symptoms and problematic areas like interpersonal therapy for social impairment linked to PTSD or behavioral treatments such as behavioral activation and mindfulness to improve depression or increase distress tolerance. In other cases (i.e., power therapy), the review concludes that there is not any evidence of efficacy. Finally, of all the approaches reviewed, technology-based treatments offer the strongest preliminary evidence. In the following section we will address the use of one of these technologies, virtual reality, in the treatment of anxiety disorders and PTSD.

Virtual Reality (VR)

Virtual reality is an Information and Communication Technology (ICT) which utilizes adjustable computer-generated simulations of reality to engage the patient in trauma-relevant scenarios. The typical VR setting involves VR software, a Head Mounted Display (HMD), a tracker, and an interaction device (such as a joystick). The user is immersed in a 3-D environment where he/she can interact with the virtual objects and experience a sense of presence, as if they were “there” in the virtual world.

The capacity of simulating reality in such a unique way has appealed to health professionals since its first developments. VR has been used to address a variety of health conditions such as pain, addiction, cognitive/physical rehabilitation, and most prominently, anxiety disorders.

Given its immersive features, VR is a powerful distraction technique that has been used for acute pain control mainly with burn patients during wound care or physical therapy (Hoffman, Doctor, Patterson, Carrougher, & Furness, 2000; Hoffman, Patterson, & Carrougher, 2000, see Keefe et al., 2012 for a review).

By far the largest body of work in the clinical application of VR has been with anxiety disorders, especially phobias. Since the publication of the pioneer work by Rothbaum, Hodges, Opdyke, Willifor, and North (1995), describing a case study of the use of VR exposure for fear of heights, VR has been demonstrated to be effective in the treatment of a wide diversity of specific phobias, including fear of flying, arachnophobia, acrophobia, claustrophobia, and driving phobia. It has also been used for the delivery of exposure in other more complex anxiety disorders like panic disorder with agoraphobia, social phobia, or PTSD. Two meta-analyses (Parsons & Rizzo, 2008; Powers & Emmelkamp, 2008) explored the efficacy of VR for anxiety disorders and Parsons et al. found an average effect size of 0.96, concluding that VR exposure is an effective treatment for a variety of anxiety disorders. In a more recent meta-analysis, Opris et al. (2012) compared the efficacy of VR exposure with traditional evidence-based treatments for anxiety disorders finding a similar efficacy at short- and long-term and a similar dropout rate.

The features of VR make this technology an attractive means to deliver exposure therapy. The key element of exposure therapy is to confront the feared objects or situations, in vivo (real situations) or using imagination. VR environments could be viewed as scenarios between real and imagined situations. VR constitutes a tool that can be used as an adjunct to in vivo or imaginal exposure or as a means to increase the acceptability of the traditional ways of applying exposure therapy.

The main advantage of using VR environments for the delivery of exposure in the treatment of anxiety disorders is the high degree of control over the feared objects or situations that is not always possible with in vivo or imaginal exposure. The VR software can prevent the occurrence of unpredictable events allowing an accurate gradation of the exposure to the feared object or situation. We can add more and more difficult feared cues to the computer-generated environment in a very progressive way, respecting the rhythm of a specific individual. This can result in the patient being more willing to start and complete the exposure program. For example, an individual with agoraphobia can be exposed to a feared situation like a trip in a train while the therapist can control moderators like the number of people present in the train. The therapist can expose the individual first to an empty train, then add a few people, then gradually increase number of people, increasing the provocative elements in the hierarchy until reaching a train that is completely crowded. VR exposure also helps in terms of being able to provoke situations for exposure tasks that would be difficult to control and deliver in the real world (e.g., a break down in an elevator). Another advantage of VR is that we can repeat the same exposure task as many times as needed without having to wait for the real situation to naturally occur again. This advantage facilitates “overlearning,” one of the processes that increases the efficacy of exposure (Marks, 1987). For example, we can repeat an airplane take-off over and over with an individual with fear of flying in a single exposure session. Also, compared to in vivo exposure VR offers a more confidential setting, given that there is no need to go out of the therapist’s office to conduct exposure tasks. That is, patients do not need to be afraid that their problem might be known to others.

In summary, VR can be a useful way of deliver exposure that can increase the acceptability of exposure therapy. In fact, there are studies exploring the acceptability of VR therapy. Garcia-Palacios, Botella, Hoffman, and Fabregat (2007) conducted a survey among people diagnosed of specific phobia. After reading a description of VR exposure or in vivo exposure, most of them reported to be more willing to be involved in VR exposure, and when making them choosing between VR or in vivo exposure, 76 % chose VR exposure. Therapists also seem to like VR therapy. Richard and Gloster (2007) conducted a survey of professional members of the Anxiety Disorders Association of America, and found that VR exposure was viewed as more acceptable, helpful, and ethical than traditional exposure-based therapies.

In this line, VR could also be a more attractive way of offering therapy to anxiety disordered people. For example, younger generations who have grown up with technology as a natural part of everyday life may be more inclined to seek treatment in this format. Thus, a therapeutic approach supported by technology could increase the acceptability of being involved in it and serve to break down barriers to care.

In summary, VR exposure has proven to be a valid and effective means of delivering exposure therapy in the treatment of anxiety disorders. Its good efficacy data and acceptability make VR exposure an alternative for applying exposure approaches with PTSD patients. In the next section we will discuss the use of this technology in the treatment of this condition.

Rationale for the Use of Virtual Reality in the Treatment of Posttraumatic Stress Disorder

VR has developed rapidly in the past 15 years and offers a promising alternative to imaginal and in vivo exposure. It may be a valuable approach to overcoming the limitations of relying solely upon the individual’s imagination and memory to recall the traumatic experience.

One of the central features of VR is the increase in focused attention. The capacity of the VR environment to draw the individual into the virtual world is described as creating “presence,” a sense of being “there” in the virtual world (Hoffman, Prothero, Wells, & Groen, 1998). Virtual reality affords opportunities to enhance the sense of presence with visual, auditory, and even haptic computer-generated experiences. The experience of presence may be a critical factor in the utility of VR exposure treatment for PTSD because it has the capacity to immerse the individual in an environment that will help recreate the situation where the trauma first occurred. VR offers rich sensory simulations of the traumatic event. This augments the imaginative capacities of the individual that may prevent cognitive avoidance and therefore enhance emotional engagement, an essential issue in the efficacy of exposure. Thus, for patients who are reluctant to engage in recollections of feared memories, the sensory-rich virtual world creates an evocative therapeutic environment which may enhance the patient’s emotional engagement.

Additionally, as in the case of other anxiety disorders, VR technology allows for graded exposure in increasingly feared virtual environments, objects, or events that can be carefully monitored and tailored to the individual patient. VR provides a safe and protected therapeutic context where there is a very accurate control over the computer-generated stimuli. The VR world could include several steps in order for the patient to progress from lower to higher levels of distress, being exposed to parts of the traumatic event in a very progressive way. For example, the world developed by Difede and Hoffman for September 11th victims includes different levels of the attack, starting from views of the World Trade Center and going up the hierarchy including, for example, the view of people jumping from the towers, all in a 3-D environment that gives the participant a first-person view. As a result of the possibility of customized and graduated exposure tasks, VR therapy experiences may increase a patient’s feelings of self-efficacy and of being an active agent of their own experience.

VR environments can also be used to include other strategies in order to go beyond the reduction of symptoms and promote resilience in order to face the future. There is already evidence of the efficacy of VR in the treatment of PTSD. Rothbaum et al. (1999) published the first case study where VR exposure was used in the treatment of PTSD with a Vietnam veteran. This team also reported data from an open trial with 16 Vietnam-era veterans (Rothbaum, Hodges, Ready, Graap, & Alarcon, 2001), revealing a trend towards reduction in some PTSD symptoms and maintenance of the therapeutic gains at 6-month follow-up. The virtual world developed for these studies was “Virtual Vietnam” and it simulated scenarios representing situations experienced by the veterans of the Vietnam War, including a rice paddy and a helicopter ride. It is important to highlight that the patients included in these studies suffered from a chronic PTSD of more than 20 years of duration. Also, the authors pointed out that the treatment did not have adverse effects. None of the patients decompensated or had to be hospitalized during the application of the treatment or follow-up.

Difede and Hoffman (2002) presented a case study on the use of VR exposure for the treatment of PTSD in a victim of the September 11th attack with positive results. Later, this group conducted a clinical trial comparing VR exposure with a waiting list condition (Difede et al., 2007), with very good results at posttreatment (effect size of 1.54) that were maintained at 6-month follow-up. It must be underlined that these authors included in their studies patients who did not respond to the traditional imaginal exposure. Therefore, they showed that VR could be a useful alternative for those patients who have not been treated successfully with imaginal exposure.

In the area of terrorism with civilian victims, another group in Israel developed a virtual world simulating a “Bus Bombing” terrorist attack (Josman et al., 2006). They tested the preliminary efficacy of this VR environment in a case study (Freedman et al., 2010) showing significant reductions of PTSD symptoms at posttest that were maintained at 6-month follow-up.

Beck, Palyo, Winer, Schwagler, and Ang (2007) reported data of an uncontrolled trial of six patients suffering PTSD resulting from motor vehicle accidents (MVA) and treated with virtual driving scenarios. The results showed reductions in PTSD symptoms as well as higher sense of presence and satisfaction with the treatment.

A line of research that is being expanding in the last few years is the use of VR exposure for the treatment of PTSD in military personnel returning from Iraq and Afghanistan. There is preliminary evidence of the efficacy of VR in this population. Rizzo et al. (2010) found that 16 out of 20 treatment completers participating in an open trial did not meet PTSD criteria after the treatment. Reger et al. (2011) conducted an open trial in a naturalistic setting reporting significant reductions of PTSD symptoms in 24 active duty soldiers. McLay et al. (2011) published data of a small randomized clinical trial comparing VR exposure to a treatment as usual condition (TAU), reporting also positive results.

These results are still preliminary, but very encouraging. All the virtual worlds described thus far for the treatment of PTSD have been designed and addressed to very specific populations that have experienced the same traumatic event. The virtual scenario was very similar for all patients. A possible limitation of this approach is that it could be difficult to reach all patients suffering different traumatic experiences. In a research setting or in specific clinical settings (i.e., mental health care for veterans), it is more common to have such specific populations. However, in a clinical setting providing general mental health care, it is typical to encounter different people with a wider variety of trauma experiences. In this case it would be more suitable to use a different approach with more flexible virtual worlds in order to be able to customize the virtual environments for different PTSD populations like assault victims, terrorism victims, sexual aggression victims, MVA, etc.

This approach is addressed by Botella’s research team in Spain. The focus in designing such flexible and tailored VR environments is not on realism, but on using customized symbols and stimuli to evoke an emotional reaction in the participant to help achieve the needed emotional processing of the trauma. The aim of this work is to design clinically significant environments for each participant, while attending to the meaning of the trauma for the individual. At the same time, the process creates a safe and protective environment that helps the patient to recover and improve their functioning in his/her life. This line of research has been conducted within the Engaging Media for Mental Health Applications (EMMA) project, a research project funded by the European Union. In this project, a VR application using an adaptive display was designed (EMMA’s world). In this world the therapist and patient work in exposure therapy going though the trauma and processing negative emotions related to it (anxiety, fear, anger, sadness). EMMA’s world is a natural environment where it is possible to change the landscape and weather in order to represent the patient’s emotions (a desert, a green countryside, snow, rain, storms, etc.). In Fig. 14.1 we offer some pictures of the different landscapes. There is also an architectural space where the patient and therapist can use different virtual elements: objects, pictures, videos, music, etc. in order to represent and work on processing the traumatic event. Patients are also given access to the “Book of Life,” a virtual book where all the patient’s virtual elements can be placed in order to help them to construct and “narrate” the trauma and its meaning in a dynamic way progressing from session to session. This VR world can be used for the treatment of PTSD and also for other stress-related disorders like adjustment disorders or pathological grief. Baños et al. (2011) published preliminary data from a controlled trial with 39 participants comparing the use of EMMA for the treatment of stress-related disorders compared to standard CBT. The results at posttreatment indicated that both treatment conditions were equally efficacious in the main outcome variables. The EMMA condition was also reported to be slightly, but significantly superior in social impairment (p < 0.034) and depression (p < 0.044).

Fig. 14.1
figure 1

Images of EMMA’s world landscapes

Full size image

Although the data are still preliminary, the EMMA approach could be a useful alternative to other VR systems that have a specific trauma approach in settings where the patients present different traumas and there is a need of a higher customization of the stimuli to conduct VR exposure.

Closing Remarks

There has been an impressive progress in the understanding and treatment of PTSD since its inclusion in DSM-III in 1980. And the research literature supports the view that CBT approaches including exposure therapy constitute the first-line treatment for this disorder.

Despite this existing evidence, there is still room for improvement given that exposure therapy in the field of PTSD seems to have a dissemination problem. As we have seen, therapists do not use exposure therapy as often as it should be recommended. There are misconceptions that are not empirically supported which suggest that exposure could exacerbate symptoms or increase treatment dropout. This seems to be more a problem for therapists who are unaware of the state of the literature, than for patients. One important direction for this work is to disseminate the benefits of exposure therapy in a more effective way. Rigorous research and training may not be enough. Perhaps better dissemination of the research data in a more “friendly” or personalized way, for example including the views and opinions of patients who had benefited from this form of treatment, could be a way to reach patients and therapists and support its effective implementation.

Another approach is to design new treatment programs for PTSD. There are a wide variety of emerging psychological treatments for this disorder. However, the results are still preliminary and none of them have been demonstrated to be superior to exposure-based approaches. It seems that some of these new programs could be used as an adjunct to exposure therapy in order to treat other comorbid symptoms like depression or social impairment.

It is also important to highlight that exposure therapy is supported by consistent findings from a number of randomized clinical trials and rigorous research. Thus, any emerging treatment should demonstrate to be at least equally effective as standard exposure therapy before recommending it as an alternative for the treatment of PTSD.

Finally, another approach could be to improve the way to deliver exposure therapy. This is the goal of VR exposure programs. VR can help to enhance the effectiveness and acceptability of exposure therapy. VR can simulate the stressful event with a high degree of realism and, therefore, help the patients regardless of their ability to imagine or engage with the trauma experience. It also permits precise control in the presentation of the feared stimuli or situations to the patient. This may prevent cognitive avoidance and therefore enhance emotional engagement, an essential issue in the efficacy of exposure. In the review by Cukor et al. (2009) about emerging treatments for PTSD, the authors concluded that technological-based approaches (VR) obtained the strongest efficacy support. We believe it is worth to continue exploring the efficacy and effectiveness of this way of delivering exposure in the treatment of PTSD. It is important to conduct randomized clinical trials comparing the efficacy of VR exposure with the gold standard, imaginal exposure, in order to determine if VR exposure is as efficacious as imaginal exposure. If that is the case (as it has been demonstrated with other anxiety disorders, cf. Parsons & Rizzo, 2008) another line of work should be to investigate if VR could have better acceptability than the traditional imaginal exposure. A possible benefit of using VR exposure would be seen in an increase in the number of people willing to start an exposure-based program. Finally, the work done by Difede et al. (2007) is another important line of research that has explored the use of VR for those individuals who do not respond to imaginal exposure. Difede and her collaborators have offered preliminary data supporting this fact.

In summary, information and communication technology, and specifically VR has significant potential as an innovative way of applying exposure therapy that could help to reach a larger number of individuals who suffer from a severe and chronic condition like PTSD. VR exposure for PTSD is an example of the progress of cognitive-behavioral therapy in the search of innovation and improvement of existing strategies for this disorder.