Effect of nature-based interventions on depressive symptoms and cognitive functions in older adults: A systematic review and meta-analysis

Depression and cognitive decline represent critical challenges in aging populations. Although nature-based interventions (NBIs) show promise in mitigating these conditions, current evidence regarding their efficacy remains inconclusive. This meta-analysis synthesized randomized controlled trials comparing NBIs against controls in adults aged ≥ 65 years. Seven databases were searched through 30 May 2025. Two reviewers independently screened studies, extracted data, and assessed risk of bias. Random-effects meta-analyses were performed using standardized mean differences, with heterogeneity assessed via I 2 statistics and Q tests. A total of 19 studies involving 1,149 older adults were included. Pooled analyses demonstrated that NBIs significantly reduced depressive symptoms ( k = 13, SMD = −0.35, 95% CI: [−0.51, −0.19]; p < 0.001) and enhanced cognitive functions ( k = 10, SMD = 0.78, 95% CI: [0.55, 1.02]; p < 0.001). Subgroup analyses suggested that spring-based NBIs conferred superior benefits compared to autumn, while higher intervention frequency (≥ 2/week) was associated with greater cognitive gains. Regarding intervention types, although between-subgroup differences were non-significant, significant improvements were observed specifically for horticultural activities and mixed NBIs, whereas other intervention types did not reach statistical significance. In conclusion, NBIs represent effective non-pharmacological strategies for alleviating depressive symptoms and enhancing cognitive functions in older adults. Optimizing intervention design may maximize therapeutic gains. These findings support integrating NBIs into geriatric care, though future high-quality research with larger sample sizes is needed to strengthen current evidence and confirm these optimal parameters. PROSPERO CRD420251045110. • First meta-analysis assessing the effects of nature-based interventions (NBIs) on depressive symptoms and cognitive function in older adults. • Evidence from 19 randomized controlled trials confirms NBIs effectively alleviate depressive symptoms and improve cognitive function. • NBIs conducted in spring demonstrate superior efficacy compared to those implemented in autumn. • Higher intervention frequency (≥ 2 sessions/week) is associated with greater cognitive gains in older adults. • Further high-quality evidence is required to confirm moderators and optimize personalized NBI strategies.