Psychological Pathways between Social Isolation and Memory Decline

Background and Purpose: Social isolation’s effect on memory decline has been well-documented. There are likely multiple mechanisms for their relationship. This study aims to examine the psychological mechanisms, more specifically, we wanted to investigate whether psychological resources depletion, or psychological stress escalation, or both are responsible for the linkage between social isolation and memory decline. We ask four questions: (1) Does social isolation increase memory decline? (2) Does social isolation reduce psychological resources? (3) Does social isolation increase psychological distress? (4) To what extent is the relationship between social isolation and memory mediated by psychological resources and distress?

Methods: We conducted linear regression and path analysis using three-wave data spanning 8 years (2008/2010 – 2016/2018) from the Health and Retirement Study. The sample included respondents aged 65 and older (N = 3,589) at baseline (T1, 2008/2010). Social isolation was measured at baseline using an index (range 0-4) based on network size, frequency of contact with family and friends, religious services participation and other social group involvement. Memory (range 0-20) was assessed by immediate and delayed recall. Psychological resources included purpose in life and perceived mastery, measured by a 7-item subscale of the Ryff Measures of Psychological Well-being and a 5-item subscale of Personal Sense of Control scale, respectively. Psychological distress included loneliness and depressive symptoms. Loneliness was measured using the 11-item UCLA Loneliness scale. Depressive symptoms were measured by the 8-item CES-D scale. We controlled for T1 measures of the dependent variables and health-related and sociodemographic covariates in the analysis.

Results: We found that social isolation reduced older adults’ sense of purpose in life (β = -0.06 SE = 0.01 p < 0.001) and perceived mastery (β = -0.04 SE = 0.01 p < 0.01), and increased their feeling of loneliness (β = 0.05 SE = 0.01 p < 0.001) and depressive symptoms (β = 0.03 SE = 0.01 p < 0.05) four years later. Social isolation at baseline was associated with memory decline eight years later (β = -0.04 SE = 0.01 p < 0.001). Path analyses revealed that purpose in life and loneliness were significant mediators between social isolation and memory, with purpose in life accounted for 20% and loneliness accounted for another 20% of the total effect of social isolation on changes in memory. Perceived mastery and depressive symptoms were not significantly associated with memory change.

Conclusions and Implications: The results suggest that purpose in life and loneliness are pathways by which social isolation exerts adverse effects on memory among older adults. Social isolation in older adults should be a target for intervention. In addition, efforts to bolster purpose in life and lessen feeling of loneliness could help to alleviate the impact of social isolation on memory among older adults. The findings also suggest that social isolation’s negative effects on health may be via both depletion of psychological resources that promote health and intensification of psychological stress that damages health.