Abstract
Exposure Therapy (ET) has demonstrated its efficacy in the treatment of phobias, anxiety and Post-traumatic Stress Disorder (PTSD), however, it suffers a high drop-out rate because of too low or too high patient engagement in treatment. Virtual Reality Exposure Therapy (VRET) is comparably effective regarding symptom reduction and offers an alternative tool to facilitate engagement for avoidant participants. Neuroimaging studies have demonstrated that both ET and VRET normalize brain activity within a fear circuit. However, previous studies have employed brain imaging technology which restricts people’s movement and hides their body, surroundings and therapist from view. This is at odds with the way engagement is typically controlled. We used a novel combination of neural imaging and VR technology—Functional Near-Infrared Spectroscopy (fNIRS) and Immersive Projection Technology (IPT), to avoid these limitations. Although there are a few studies that have investigated the effect of VRET on a brain function after the treatment, the present study utilized technologies which promote ecological validity to measure brain changes after VRET treatment. Furthermore, there are no studies that have measured brain activity within VRET session. In this study brain activity within the prefrontal cortex (PFC) was measured during three consecutive exposure sessions. N = 13 acrophobic volunteers were asked to walk on a virtual plank with a 6 m drop below. Changes in oxygenated (HbO) hemoglobin concentrations in the PFC were measured in three blocks using fNIRS. Consistent with previous functional magnetic resonance imaging (fMRI) studies, the analysis showed decreased activity in the DLPFC and MPFC during first exposure. The activity increased toward normal across three sessions. The study demonstrates potential efficacy of a method for measuring within-session neural response to virtual stimuli that could be replicated within clinics and research institutes, with equipment better suited to an ET session and at fraction of the cost, when compared to fMRI. This has application in widening access to, and increasing ecological validity of, immersive neuroimaging across understanding, diagnosis, assessment and treatment of, a range of mental disorders such as phobia, anxiety and PTSD or addictions.
Highlights
Specific phobia is a psychiatric disorder characterized as a persistent fear that is either unreasonable or excessive, caused by the presence or anticipation of a specific object or situation (DSM—V American Psychiatric Association, 2013)
The analysis showed no difference in brain activity between the training room and the pit room at the beginning of Virtual Reality Exposure Therapy (VRET), that indicates that participants with acrophobia fail to activate the dorsolateral PFC (DLPFC) and medial prefrontal cortex (MPFC) when exposed to fear-evoking virtual stimuli
The current study found within-session effects reflected in increased brain activity at the end of VRET in the DLPFC and MPFC
Summary
Specific phobia is a psychiatric disorder characterized as a persistent fear that is either unreasonable or excessive, caused by the presence or anticipation of a specific object or situation (DSM—V American Psychiatric Association, 2013). Previous clinical trials demonstrated that in vivo Exposure Therapy (ET) appears to be a more effective treatment for specific phobias compared to imaginal ET and wait-list control group or placebo (Choy et al, 2007). In vivo ET has limited control of the exposure situation, could be expensive and take a lot of time (Riva, 2005). It puts patients in a potentially distressing situation, where they need to face the real threat or embarrassment related to some public aspects of in vivo treatment (Rizzo et al, 2007). Previous studies on ET indicated that excessive, or the lack of emotional engagement during a therapy session could be a predictor for negative treatment results (Jaycox et al, 1998; Rothbaum and Schwartz, 2002)
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