Immersive Virtual Reality to Simulate Psychedelic-Like Experiences in Adults with Obsessive–Compulsive Disorder: A Single-Arm Multicentre Feasibility Study

Abstract

This project investigates the feasibility, acceptability, and safety of using immersive virtual reality (VR) to simulate psychedelic-like experiences in adults with obsessive–compulsive disorder (OCD). OCD is a chronic and impairing condition characterised by intrusive thoughts, repetitive behaviours, and marked cognitive and behavioural rigidity. A substantial proportion of patients experience insufficient symptom relief, limited engagement, or internal resistance to conventional therapeutic approaches. This highlights the need for adjunctive interventions capable of targeting psychological inflexibility through alternative experiential methods. The primary aim of this single-arm multicentre feasibility study is to determine whether a single VR session designed to evoke psychedelic-like visual and auditory phenomena is feasible, acceptable, and safe for patients with OCD. Psychedelic-assisted therapies have shown promise in enhancing psychological flexibility and reducing rigid patterns of thinking across several psychiatric conditions, but their clinical use remains limited by legal and safety constraints. VR offers a controlled, substance-free alternative for eliciting selected aspects of psychedelic phenomenology. The study therefore examines whether such an intervention can be delivered safely in clinical settings, whether patients tolerate and engage with the experience, and whether the session produces measurable short-term changes in affect, cognitive flexibility, metacognitive beliefs, and momentary OCD symptom intensity. Approximately 24 adult participants will be recruited across two clinical sites: the University Medical Center Hamburg-Eppendorf (Germany) and the University of Catania (Italy). Recruitment is expected to begin in January 2027. The study follows a single-arm, open-label pre–post design. All participants complete: Baseline assessments (T0) including diagnostic interviews (DIAMOND or QuickSCID-5), OCD severity (Y-BOCS), anxiety (GAD-7), depression (BDI-II), and medication status. Pre-intervention assessments (T1) immediately before the VR session. A single VR session, delivered using a Meta Quest 3 headset and developed by PatientZero Games, in a controlled environment. Post-intervention assessments (T2) immediately after the session. The VR experience is designed to simulate psychedelic-like perceptual and self-related phenomena without pharmacological substances. Primary outcomes focus on feasibility and acceptability: Recruitment and retention rates Completion rate (target ≥ 70%) User experience (UEQ-S) Safety indicators including cybersickness (SSQ) and adverse events These outcomes will determine whether the intervention can be implemented reliably in clinical settings and whether patients find the experience tolerable and engaging. Secondary outcomes explore preliminary psychological effects: Acute OCD symptom intensity (A-YBOCS) Positive and negative affect (PANAS) Metacognitive beliefs related to thought control (MCQ-30/MKF-30, NC subscale) State cognitive flexibility (State-CFI) Psychedelic-like effects such as ego dissolution (EDI) VR presence and immersion (IPQ) Although the study is not powered for efficacy testing, pre–post changes will provide initial indications of whether psychedelic-like VR experiences may influence mechanisms relevant to OCD, such as rigidity, affect, and cognitive flexibility. This feasibility study represents the first application of psychedelic-like VR in a clinical OCD population. Its findings will: Establish whether the intervention is safe and acceptable for patients receiving inpatient treatment. Identify the most sensitive and clinically meaningful outcome measures for future trials. Provide effect size estimates and procedural insights necessary for designing a subsequent randomised controlled trial. By integrating immersive VR with established clinical assessments, this project aims to open a new line of investigation into experiential interventions that target psychological rigidity, one of the core maintaining mechanisms of OCD.