Animal-assisted interventions for depression in older adults: an umbrella review with meta-analysis and trial sequential analysis

Background: Depression affects up to 30% of older adults and is associated with increased morbidity and mortality. Animal-assisted interventions (AAIs) - usually known as “pet therapy” - have emerged as promising complementary approaches, yet evidence synthesis remains fragmented. Objective: To comprehensively evaluate the effectiveness of AAI in reducing depressive symptoms among older adults through an umbrella review of systematic reviews and meta-analyses, incorporating trial sequential analysis. Methods: We systematically searched PubMed, Embase, and Cochrane Library through September 2025 for systematic reviews and meta-analyses examining AAIs for depression in older adults. Quality assessment was performed using AMSTAR-2. We calculated the Corrected Covered Area to assess overlap between meta-analyses, re-analyzed primary study data to avoid double-counting, and conducted trial sequential analysis to evaluate evidence sufficiency. Results: Five systematic reviews encompassing 27 unique primary studies with 2,156 participants were included. The pooled random-effects meta-analysis demonstrated a significant reduction in depressive symptoms (SMD = 0.73; 95% CI: 0.57–0.89; p < 0.001) with moderate heterogeneity (I² = 43.4%). Trial sequential analysis revealed that the cumulative Z-curve crossed monitoring boundaries at 75% of the required information size, confirming evidence sufficiency. The Corrected Covered Area was 20.4%, indicating moderate overlap between meta-analyses. Conclusions: AAIs are associated with clinically meaningful reductions in depressive symptoms among older adults. Trial sequential analysis confirms that sufficient evidence exists to support this conclusion. AAIs represent a valuable, low-risk, patient-centered complement to conventional depression treatments in geriatric care. PROSPERO registration: [CRD420251250448]