Examining the Combined Effects of Social Isolation and Loneliness on Memory: A Systematic Review.

Background: Some research suggests social isolation and loneliness are important risk factors for reduced successful aging and cognitive health. However, findings are inconsistent and no prior systematic review has investigated whether social isolation and loneliness are associated with the memory domain of cognition. This review examined whether social isolation and loneliness individually and jointly affected the memory of middle- and older-aged adults.

Methods: We used PubMed, PsycInfo, and Scopus to search for comparative studies that examined the impact of both loneliness and social isolation (e.g., social activity, social networks) on memory (including all subtypes) in populations aged ≥ 45 years. Three raters performed data extraction and risk of bias assessment using the Joanna Briggs Institute checklist. Data were synthesized narratively following the Synthesis without Meta-Analysis guideline.

Results: In 12 included articles, higher levels of loneliness and social isolation (combining a range of different indicators) were associated with lower memory performance, where the interaction between loneliness and social isolation had the largest adverse effect on memory, followed by social isolation alone, and followed by loneliness alone. However, substantial heterogeneity was observed in the composition of the two most common indicators of social isolation (social network size, social activity participation), with the magnitude of most results being clinically non-important. Most articles had moderate risk of bias.

Conclusion: This review found an inverse association between social isolation/loneliness and memory, and outlines future steps to systematically combine the two constructs and measure social isolation in a consistent, multi-modal format.