Oct 01 2019

Virtual Reality Therapy for PTSD

Post-Traumatic Stress Disorder (PTSD) results from exposure to traumatic events. Soldiers in war, for example, are at high risk of PTSD because of repeated exposure over time. But even a single event, like experiencing the attacks on 9/11, can cause PTSD. The prevalence in the US is about 8.7%. Symptoms include:

“the development of characteristic symptoms, such as distressing memories or dreams about the traumatic event, flashbacks, psychological distress produced by internal or external cues that symbolize the traumatic event, physiological reactions, avoidance of associated stimuli, and negative alterations in cognitions and mood.”

The only real proven therapy for PTSD is exposure therapy. This has many variations, but at its core it involves exposure to stimuli that triggers PTSD symptoms or simulations of the initial trauma, while undergoing some type of cognitive therapy. The mechanism of exposure and the exact nature of the cognitive therapy vary, but the basic formula is the same. There are many treatments (such as eye movement or tapping therapy) that include additional features to the therapy, but the evidence shows that these extra features are superfluous and add nothing to the efficacy of the intervention. Every intervention that works seems to include some form of exposure therapy.

Much of the clinical research therefore focuses on optimizing this therapy. There are many variables, and it can be tricky to control for them well with such an intervention, but the research grinds forward. The working theory is that the traumatic event has become associated with the trauma itself, and so people avoid similar stimuli (locations, crowds, anything that might remind them of the traumatic event). But this avoidance locks in the negative association. Exposure therapy re-exposes patients to the conditions of the trauma, but in a safe space and without the associated trauma. This way the brain habituates to the stimuli and essentially forgets the association with trauma.

This produces clinically relevant improvement in about two-thirds of cases. But that still leaves many patients with treatment-resistant PTSD.

One relatively new element to therapy is using virtual reality for the exposure part of the therapy. I say “relatively” new because I found a case report from 2002 – 17 years ago. This reinforces how long clinical research takes.  The treatment is still considered experimental, with reviews (which I will get to) stating that more research is needed.

Exposure therapy often involves the subject simply imagining the trauma. It may also involve exposure to triggers. But obviously, if a vet has PTSD from battlefield trauma, there is no way to exposure them to that situation directly. Therefore the re-imagining method is primarily used. However, this method does not work for everyone. Some people may find it difficult to mentally project themselves into the traumatic situation or to maintain it long enough.

This is where virtual reality (VR) comes in. I have discussed VR before – having experienced it myself I can tell you that it essentially works. What this means is that the VR experience is sufficient to “trick” the brain into treating the virtual situation as real, even when you may know cognitively that it isn’t. One basic demonstration of this is the “plank experience.” In this VR game you walk a virtual plank high up in a building. Even though you know you are safe in your home, your every instinct is telling you that you are in grave danger. Your brain buys the virtual illusion.

To further understand how compelling this is it is necessary to understand that our perception of reality is all constructed in any case. Your brain compares multiple sensory streams simultaneously and synchronizing them with each other and with internal models of reality. The end result is a seamless cognitive illusion of reality. This constructive process can be hacked, and VR is a remarkably effective way of doing it.

VR is much more effective than viewing a monitor or video screen. In fact, it’s not just a quantitative difference – it’s a qualitative difference, a separate phenomenon. When viewing a screen your brain does not perceive movement on the screen as movement in the world. However, there is a critical threshold where this starts to take effect. For really big wrap-around monitors, you can start to get some vertigo with movement (the mismatch between what your eyes see and what your body feels). This probably has something to do with peripheral vision. With VR your visual field is full (even if it is currently restricted to 110 degrees for most systems).

I also think based on my experience that the fact that when you look around the image tracks with your movements really sells the illusion. Again this makes neurological sense – my brain feels my head movements and my vision syncs with it, and so the sensory loop is closed and the illusion is complete.

Therefore – a VR experience, which can be very compelling, could be a convenient and effective method of exposure for PTSD exposure based therapy. The clinician can theoretically have complete control over the exposure. A soldier can actually be placed in a virtual battlefield. This is not dependent on their ability to imagine. But, they are physically perfectly safe.

There are two systematic reviews published in 2019 which essentially come to the same conclusion. VR-based exposure therapy for PTSD is at least as effective as current active treatments, and superior to controls. However, it may not work significantly better than current treatments. There does appear to be a dose-response effect, however, with longer treatments being more effective.

However, there is already a new version of VR therapy called 3MDR, which incorporates motion with the VR experience. This is currently being studied, but early case reports indication it may produce additional improvement beyond standard therapy. This treatment could be, for example, walking on a treadmill with the VR goggles on, so that the patient walks toward the trigger rather than avoiding it.

At the very least VR is an effective method of exposure-based therapy for PTSD and may be more convenient for some. It is likely that no one method will be the best for every person, and the more options there are the larger a percentage of people who will respond to at least one intervention.

But as is often the case, more research needs to be done.

 

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