Virtual Reality-Delivered Exposure for Contamination Concerns in Adults With Obsessive-Compulsive Symptoms: Single-Arm Pilot Study.

Background: Exposure and response prevention is a first-line intervention for obsessive-compulsive disorder (OCD), yet many individuals with contamination concerns do not access care. Virtual reality exposure-based therapy (VRET) may improve scalability and acceptability. Objective: This pilot study evaluated the feasibility and acceptability of a standardized single-session VRET protocol targeting contamination concerns and whether it elicited within-session anxiety and exploratory contamination symptom change at 1-month follow-up. Methods: We conducted a single-arm pilot study in adults with elevated contamination concerns and no formal OCD diagnosis, recruited via convenience sampling. Participants completed a baseline survey, an in-laboratory VRET session using a standardized virtual public toilet environment, and a follow-up survey. Outcomes included momentary anxiety (Subjective Units of Distress Scale) during exposure, affect (positive and negative affect schedule) across time points, and contamination symptoms (Obsessive-Compulsive Inventory-Revised contamination subscale) at baseline and follow-up. Usability (System Usability Scale) and VR sickness were also assessed. Within-session outcomes used repeated-measures ANOVA or Friedman tests; symptom change used paired t tests (α=.05); point estimates include 95% CIs. Missing data were addressed using multiple imputation (random forest; m=5); 37.5% of participants did not complete the follow-up survey (overall missingness: 5.47%). Results: Sixteen participants were included (aged 18-32 years). Anxiety increased during exposure tasks and decreased after virtual hand washing in both trials (Exposure 1 Friedman Test: χ²3=28.56; P<.001; W=0.6); Exposure 2 repeated measures ANOVA: F1.85, 27.81=5.35; P=.01; Greenhouse-Geisser corrected=0.058. Negative and positive affect both changed significantly across time points (negative affect: Friedman Test: χ²3=13.76; P=.003; W=0.29 and positive affect: repeated measure ANOVA: F3, 45=4.60-4.71; P=.006-.007; Greenhouse-Geisser corrected=0.07-0.073). Contamination symptoms did not significantly change from baseline to follow-up (mean change 1.30, SD 3.39; 95% CI -0.36 to 2.96; P=.12). Usability was adequate (System Usability Scale mean 69.5, 95% CI 62.79-76.21). Conclusions: This study is among the first to systematically evaluate a standardized single-session contamination-focused VRET protocol in adults with elevated contamination concerns who did not meet diagnostic criteria for OCD, a subthreshold population underrepresented in prior VRET research, which has focused on clinically diagnosed samples and multisession protocols. The protocol proved feasible and acceptable, eliciting within-session anxiety and providing benchmarks in existing clinical literature. Contamination symptom change at 1-month follow-up was not statistically significant, and the effect size estimate was sensitive to the missingness assumption, underscoring the need for adequately powered multisession designs in future trials. The usability profile and VR sickness levels that did not prevent session completion suggest self-administered or minimally supervised delivery warrants evaluation, with implications for scalable early intervention in individuals with elevated contamination concerns who have not accessed formal treatment.