Mediation analysis of social isolation and mortality by health behaviors

The Relationship Between Social Isolation and Cognitive Frailty Among Community-Dwelling Older Adults: The Mediating Role of Depressive Symptoms

Purpose

Social isolation and depression have an impact on cognitive frailty. However, the underlying mechanisms between these variables have not been well defined. This study aims to investigate the mediating role of depressive symptoms in the association between social isolation and cognitive frailty among older adults in China.

Methods

From Mar 2023 to Aug 2023, a cross-sectional study was conducted with 496 community-dwelling older adults aged ≥60 years in Nanjing, Jiangsu Province, China. Demographic information was collected using the General Information Questionnaire. The Lubben Social Network Scale-6 (LSNS-6), Geriatric Depression Scale 15-item (GDS-15), Montreal Cognitive Assessment (MoCA), Clinical Dementia Rating (CDR), and FRAIL scale were used for the questionnaire survey. Multiple linear regression and binary logistic regression were utilized to explore the associations among social isolation, depressive symptoms, and cognitive frailty, and Bootstrap analysis was used to explore the mediating role of depressive symptoms in social isolation and cognitive frailty.

Results

Linear regression results revealed that social isolation was positively associated with depressive symptoms (β = 0.873, p < 0.001). Logistic regression analysis showed that social isolation (OR = 1.769, 95% CI = 1.018~3.075) and depressive symptoms (OR = 1.227, 95% CI = 1.108~1.357) were significantly associated with cognitive frailty. Mediation analysis demonstrated that depressive symptoms significantly mediated the relationship between social isolation and cognitive frailty, with an indirect effect of 0.027 (95% CI = 0.003~0.051), and the mediating effect accounted for 23.6% of the total effect.

Conclusion

Social isolation is associated with cognitive frailty in community-dwelling older adults, and depressive symptoms partially mediate the effect between social isolation and cognitive frailty. Active promotion of social integration among older individuals is recommended to enhance their mental health, reduce the incidence of cognitive frailty, and foster active aging.

Benchmarking Social Isolation, Loneliness, and Smoking: Challenges and Opportunities for Public Health

Over the past decade, the health implications of social isolation and loneliness garnered global attention due in part to a widely cited meta-analysis that benchmarked associations between cigarette smoking and mortality with associations between several social-relationship measures and mortality. Leaders in health systems, research, government, and popular media have since claimed that the harms of social isolation and loneliness are comparable to that of cigarette smoking. Our commentary examines the basis of this comparison. We suggest that comparisons between social isolation, loneliness, and smoking have been helpful for raising awareness of robust evidence linking social relationships and health. However, the analogy often oversimplifies the evidence and may overemphasize treating social isolation or loneliness at the individual level without sufficient attention on population-level prevention. As communities, governments, and health and social sector practitioners navigate opportunities for change, we believe now is time to focus greater attention on the structures and environments that promote and constrain healthy relationships.

A systematic review and meta-analysis of 90 cohort studies of social isolation, loneliness and mortality

The associations between social isolation, loneliness and the risk of mortality from all causes, cardiovascular disease (CVD) and cancer are controversial. We systematically reviewed prospective studies on the association between social isolation, loneliness and mortality outcomes in adults aged 18 years or older, as well as studies on these relationships in individuals with CVD or cancer, and conducted a meta-analysis. The study protocol was registered with PROSPERO (reg. no. CRD42022299959). A total of 90 prospective cohort studies including 2,205,199 individuals were included. Here we show that, in the general population, both social isolation and loneliness were significantly associated with an increased risk of all-cause mortality (pooled effect size for social isolation, 1.32; 95% confidence interval (CI), 1.26 to 1.39; P < 0.001; pooled effect size for loneliness, 1.14; 95% CI, 1.08 to 1.20; P < 0.001) and cancer mortality (pooled effect size for social isolation, 1.24; 95% CI, 1.19 to 1.28; P < 0.001; pooled effect size for loneliness, 1.09; 95% CI, 1.01 to 1.17; P = 0.030). Social isolation also increased the risk of CVD mortality (1.34; 95% CI, 1.25 to 1.44; P < 0.001). There was an increased risk of all-cause mortality in socially isolated individuals with CVD (1.28; 95% CI, 1.10 to 1.48; P = 0.001) or breast cancer (1.51; 95% CI, 1.34 to 1.70; P < 0.001), and individuals with breast cancer had a higher cancer-specific mortality owing to social isolation (1.33; 95% CI, 1.02 to 1.75; P = 0.038). Greater focus on social isolation and loneliness may help improve people's well-being and mortality risk.

Sex-specific impacts of social isolation on loneliness, depressive symptoms, cognitive impairment, and biomarkers: Results from the social environment and biomarker of aging study

OBJECTIVES

To investigate sex-specific associations between social isolation and psychological outcomes and biomarkers among community-dwelling middle-aged and older adults using a nationally representative population-based cohort study.

METHODS

Data from 757 participants from the Social Environment and Biomarkers of Aging Study (SEBAS) were retrieved for analysis, and all participants were stratified by sex. The associations between social isolation and psychological outcomes (loneliness, depressive symptoms, and cognitive impairment) at the 4-year follow-up were examined by multivariate logistic regression models, and associations between social isolation and biomarkers at the 4-year follow-up were examined by multivariate generalized linear models (GLMs).

RESULTS

For men, social isolation was not associated with the development of loneliness. However, being married (adjusted odds ratio (aOR) 0.32 [95% confidence interval (CI) 0.13-0.74], p<0.001) was associated with a lower risk of loneliness, indicating potential protective effects of marriage for men. On the other hand, social isolation was associated with a 2-fold higher risk of loneliness in women (aOR 2.26 [1.01-5.09], p<0.001). Social isolation was not associated with depressive symptoms after adjusting for other demographics. For men, being married (aOR 0.51 [0.26-0.99], p<0.05) or having good self-reported health (aOR 0.44 [0.21-0.92], p<0.05) was protective against depressive symptoms. For women, only good self-reported health (aOR 0.30 [0.13-0.70], p<0.01) provided protective effects against depressive symptoms. Similarly, other demographic factors (being married and having a higher educational level) but not social isolation were associated with lower risks of cognitive impairment. No significant associations were noted between social isolation and selected biomarkers.

CONCLUSIONS

Sex-different associations between social isolation and loneliness were noted; the effects of demographic factors, such as being married, self-reported health status, and high education levels, on subsequent loneliness, depression, and cognitive function were also sex-different. Further intervention studies are needed to explore sex-specific approaches to deal with the interplay of social isolation, loneliness, psychological outcomes and other demographic factors.