Virtual reality in psychosis: Experiments with social risk environments

Epidemiological studies have shown high rates of psychotic disorders in densely populated urban environments and among immigrants. The exact nature of these exposures and the underlying mechanisms are largely unknown. One hypothesis is that social environmental exposures may induce psychological and physiological alterations that can be traced to a final common pathway of cognitive biases and/or altered dopamine neurotransmission, resulting in psychosis. It is difficult to investigate social mechanisms, because measurement of the highly complex and dynamic social environment of individuals remains a major challenge. Virtual Reality technology offers the possibility to expose individuals to controlled social environments and to measure their responses directly. For this pilot study, 17 patients with a first episode of a psychotic disorder were recruited from a specialist service for early psychosis in The Hague. The virtual environment was a café with an indoor and an outdoor part. Participants could navigate in the virtual environment using a Logitech Chillstream Gamepad. They wore an Emagin Z800 3D Visor with 40 degrees diagonal Field of View, and built-in 3DOF tracker. The number of avatars in the café (population density) and the ethnic appearance of the avatars (ethnic density) could be varied. Avatars were programmed to exhibit neutral behavior. All subjects were exposed to three social environmental stress conditions: [1] low (high own ethnic density/low population density), [2] medium (low own ethnic density/low population density, or high own ethnic density/high population density) and [3] high (low own ethnic density/high population density). The design was cross-over, starting with low stress as baseline condition. The other experiments were randomized for order of condition. Paranoid thoughts (GPTS), social anxiety (SIAS) and cognitive biases (DACOBS) were measured before the experiments, paranoid thoughts about avatars (SSPS) were assessed after each condition. Participants also completed questionnaires about simulator sickness (SSQ) and sense of presence (IPQ). Paranoid thoughts about avatars were reported by 58.8% (N=10) of the participants. Patients with paranoid thoughts about avatars had significantly more symptoms of paranoia and social anxiety in real life than those without virtual paranoid thoughts. Cognitive biases predicted paranoid thoughts about avatars, in particular Theory of Mind and Self as Target biases. Level of paranoid thoughts about avatars increased with social environmental stress (mean SSPS scores 15.9 [SD, 10.2], 16.9 [SD,10.6] and 17.8 [SD, 13.7] in low, medium and high stress condition respectively). Symptoms of simulator sickness were low, presence scores were satisfactory. It is feasible and safe to use virtual social environments in patients with psychotic disorders. A substantial proportion of patients had paranoid thoughts about avatars. Symptoms in real life were associated with symptoms in the virtual environment. Epidemiological associations can be tested in virtual experiments, since variations in ethnic density and population density influenced level of paranoid thoughts about avatars. VR is a promising new tool in etiological research of psychosis