Linkages between functional independence, depressive symptoms, and social networks in aging populations: a systematic review

Activities of daily living (ADL) and instrumental ADL (IADL), main indicators of functional independence in older adults, are closely associated with depression and social networks and represent a critical determinant of well-being. Despite the growing body of research, both original and review articles to date have been limited in their ability to provide a comprehensive and coherent explanation of the interrelationships among these three domains, largely due to methodological constraints. Accordingly, this study systematically reviewed a wide range of publications addressing functional ability, depression, and social networks in older adults, with the aim of providing evidence-based insights to inform strategies for maintaining well-being and preparing for functional decline in aging populations. The synthesized findings indicate that declines in functional ability, as reflected by impairments in IADL/ADL, are associated with reduced instrumental ADL, increased depressive symptoms, and decreased social participation, collectively contributing to a self-reinforcing cycle of functional and psychological deterioration. Notably, this review demonstrates that while functional disability increases the risk of depression, robust social networks serve as protective factors that mitigate both functional and psychological decline.