Effects of social isolation, loneliness and frailty on health outcomes and their possible mediators and moderators in community-dwelling older adults: A scoping review

Over the past decade, the quantity and quality of social relationships in later life have become one of the main challenges facing an aging society. Our aims were to map and synthesize the literature addressing the effects of loneliness, three aspects of social isolation, including social networks, social support, and social participation, and frailty on health outcomes and their mediators and moderators among older adults. We conducted a scoping review and searched for articles published in English and French from 2001 up to 2019 in the following databases: Medline, Embase, CINAHL Plus, Scopus, Web of Science and PsycINFO. Our database search initially resulted in 4001 articles of which 1832 were excluded; 26 were eligible. Most of the included studies revealed associations between social isolation, loneliness and frailty. The majority of studies found evidence of associations between frailty and their adverse outcomes; however, only few studies found a relationship between social isolation and health outcomes. In spite of the established link between frailty and adverse outcomes, no study looked at how social isolation and loneliness can alter adverse outcomes of frailty. No study investigated the role of frailty or social isolation and loneliness as a mediator on the pathway related to health. Evidence is limited in examining the role of frailty or social isolation and loneliness as a moderator and mediator. Longitudinal research combining both social isolation and loneliness are warranted to explore whether social isolation or loneliness has more deleterious effects on frailty and health outcomes.