Loneliness trajectories in older adults: A systematic review

BACKGROUND: Loneliness in older adults is a critical public health issue with dynamic changes over time. Understanding its longitudinal patterns is vital for identifying high-risk individuals and developing timely interventions. This review synthesizes evidence on loneliness trajectories, their predictors, and associated health outcomes in older populations. METHODS: A systematic search across nine databases (PubMed, Web of Science, Embase, Cochrane Library, CINAHL, PsycINFO, CNKI, VIP, Wanfang) was conducted from inception to December 1, 2024, updated on August 18, 2025, focusing on longitudinal studies of adults aged ≥60 years. Quality was assessed using JBI tools, and a narrative synthesis was performed due to methodological heterogeneity. RESULTS: Of the 2985 screened records, 16 studies met the predefined inclusion criteria. Fifteen of these studies were rated as moderate or high quality. Despite heterogeneity in analytical approaches, four loneliness trajectory patterns were identified: stable-low, stable-high, ascending, and descending. The stable-high and ascending trajectories were consistently associated with adverse health outcomes, including accelerated cognitive decline and greater severity of depressive symptoms. Key predictors of high-risk loneliness trajectories included social isolation, functional impairment, and exposure to major life stressors. CONCLUSIONS: Loneliness among older adults follows heterogeneous trajectories, with the stable-high and ascending patterns indicating the highest risk for adverse health outcomes. These findings underscore the need for early screening of key risk factors and the implementation of trajectory-tailored interventions. Future research should prioritize standardized loneliness measurement tools and integrated analytical approaches to enhance the comparability of findings and their translation into clinical practice.