The aim of this systematic review was to investigate the effect of using VR in the treatment of patients with paranoia or paranoid delusions. Studies have shown that patients with paranoia feel interacted in the VR environment and experience thoughts of persecution (39). According to previous studies, VR-based interventions have been acceptable and effective in improving mental illnesses (40).
Paranoid patients often have suspicious thoughts in social situations and in dealing with people. Anxiety is also one of the main symptom in these people (41). The use of VR has various purposes in the treatment of patients with paranoid, including eliminating the paranoid thoughts, reducing social anxiety, increasing community participation, and changing their negative beliefs about themselves and others. Ultimately patients should believe that they are safe from what they are afraid of, and thoughts of suspicion about people are wrong. Therefore, the aim of the reviewed studies here, was to investigate the effect of VR-based interventions for improving the symptoms of the disorder (33–38).One study evaluated paranoia, as well as positive and negative affects and showed a decrease in paranoia and negative affects, but no significant effect on positive mental state (36).
VR technology provides many features to increase people's sense of immersion, especially in programs that focus on treating social anxiety disorders. To this end, avatars were designed to be more realistic and sociable in order to better communicate with patients (42). The same happens for patients with paranoia. VR provides a safe environment for the patient, and allows therapists and researchers to accurately identify the paranoid symptoms that may arise as a result of exposure. Different hardware and software are used to create a virtual environment. Head-mounted display and 3DOF tracker have been used to move in the laboratory environments. In a study that has used a camera to create an environment, a 15 × 15-meter portable room with a variety of equipment has been used including seating area, screen and etc. Various softwares are also used to design virtual reality, of which Unity3D is more common. In studies that used Unity3D, XVR and Vizard software to design virtual reality, few scenarios were created. In one study, a camera was used to create a virtual environment that allowed the recording of several video clips from different social situations. The expense of the equipment, and lack of VR specialists, especially for the mentally ill, has limited the practice (25). This is reflected in the partially low number of studies we could include. Though this might change when more evidences are provided about the effectiveness.
Different scenarios have been designed as the social environment in which the patient might get involved in the daily life. For example, in one study, patients were asked to walk on a virtual street, which was conducted in two phases, including a practice trial and two experimental trials. The walk was about 250 meters, with a corner changing the direction in the midway, and finally ends when turning left (33). Scenarios are logically designed based on the nature of the target symptom, and range from starting a conversation for improving social skills of patients with autism (43).
Three of the reviewed studies were conducted by a same team, with similar technology, scenarios and intervention method. A cost-effectiveness analysis was added to the newest. Accordingly, this intervention improves social participation, reduces paranoid ideation and social anxiety. Although the VR technologies are expensive, the intervention is cost-effective in a long-term follow-up (35, 36, 38).
A recent systematic review concluded that VR based treatments are effective interventions for psychosocial remediation in schizophrenia (44). Majority have used non-immersion environments making it possible to create the desired setting and avatars that interact with patients, though immersion environments might be the one step beyond. Though the review is not determining, except for one study which states that some patients did not consider VR environments to be real. While being aware of virtual nature of the environment might reduce patients' anxiety, sufficient immersion is needed to create a strong sense of presence and emotional engagement that is necessary for a successful treatment (34).
The limitations mentioned by the reviewed studies are related to the momentary evaluations of the interventions, and the limited number of scenarios. Despite evidence for cost-effectiveness, the high cost of the technology is one of the obstacles to widespread use, and long-term review is needed for a conclusion (37, 38). Moreover, results of two studies are limited by the absence of a control group (34, 35). The fact that some patients (probably with deeper psychopathology) might be afraid to participate is also limiting generalizability of the results (33). Finally, the number of studies is small, though they show promising effect of VR-based interventions for improving paranoia.
Studies can address the limitations mentioned above by a larger sample size, comparing the results to a control group and considering a longer follow up duration. It might be noteworthy to include effect of gender, and duration of the disorder. Manifestation of psychiatric symptoms is influenced by several psychological factors. Experience of the reviewed studies indicate that measuring different psychological factors might give a better understanding of etiology as well as deeper insight to effect of the VR-based intervention. A good example might be the comprehensive approach for understanding the cognitive and behavioral components of how a patient reacts to the environmental stimuli, than includes coping styles, mental states, personality characteristics, cognitive ability as well as details of the VR environment. Application of VR-based interventions within different social context and using suitable scenarios, might provide more interesting findings as well.
This study has some limitations. One common limitation for all systematic review studies is the bias in the selection of articles, therefore the search strategy was planned to include all of studies in this field. Though only papers published in English were included. We could not succeed to reach the full text of one study as described before.