Effectiveness of virtual reality-based nature interventions in promoting mental health outcomes among older adults with cognitive impairment: a systematic review and meta-regression analysis

Objective This systematic review and meta-regression evaluated virtual reality‑based nature interventions for older adults with cognitive impairment.Methods Following PRISMA 2020 and a registered PROSPERO protocol (January 2000–December 2025), we identified randomised controlled trials from nine databases and two registries. Eligible interventions used simulated nature as the primary therapeutic component. Random‑effects models pooled standardised mean differences (SMDs) and risk ratios (RRs).Results Twenty‑four RCTs (N = 1,534) were included. VR nature interventions significantly improved depression (SMD = −1.17), anxiety (−1.45), stress/distress (−1.38), apathy (−1.33), loneliness (−1.32), agitation (−1.69), and overall neuropsychiatric symptoms (−1.34). Quality of life improved (mental health‑related SMD = 1.26; global SMD = 1.14; mood/positive affect SMD = 1.18). Sleep quality improved (RR = 3.44). Engagement favoured VR (SMD = 1.07), while physiological stress markers showed mixed effects (SMD = −0.72). Dichotomous outcomes had no heterogeneity (I² = 0%); continuous outcomes showed substantial heterogeneity (I² > 90%). Meta‑regression found a modest positive association between intervention duration and effect size (β = 0.01/week).Conclusions VR‑based nature interventions may improve mental health and quality of life in older adults with cognitive impairment. However, large effect sizes, high heterogeneity, and potential small‑study effects warrant cautious interpretation.