The Cognitive Health Risk of Social Isolation Mediated By Dietary Risks: A Study with Older Korean Americans

Background/Purpose: Social isolation, defined as a lack of social relationships, is a critical social determinant of various health domains, including cognitive health. Older adults are particularly susceptible to social isolation because of aging-related factors, such as retirement, death of relatives or friends, chronic illness, living alone, and sensory impairment. Extensive literature has linked social isolation to cognitive decline and dementia in the later years of life; one study reported that 6.7% of dementia cases in the US are associated with social isolation. Expanding on this link, we investigated the mediating role of dietary risk in older Korean Americans, given evidence that healthy dietary habits can mitigate the adverse impact of social isolation on the health and mortality of older adults. It is of note that this mediation has not been explored in older ethnic immigrants, despite their heightened vulnerability in social, behavioral, and cognitive health.

Methods: Using data from the Study of Older Korean Americans (N = 1, 985, mean age = 73.2), generalized structural equation modeling was examined with social isolation as an exposure, dietary risk as a mediator, and cognitive impairment as an outcome. Social isolation (0=not isolated; 1=socially isolated) was measured using the Lubben Social Network Scale-6. Cognitive impairment (0=not impaired; 1=cognitively impaired) was assessed using the Mini-Mental State Examination by trained research personnel. Dietary risk was derived from five items on dietary patterns and barriers to healthy aging drawn from the National Survey of Older Koreans, with a higher score indicating greater dietary risks. Covariates included age, gender, marital status, education, financial status, length of stay, and the total number of chronic medical conditions.

Results: Our results showed that 24% of the study participants experienced social isolation from their family and friends. Multivariate models showed that social isolation was associated with greater cognitive impairment (OR = 2.13, 95% CI = 1.56, 2.91). In generalized structural equation models, we observed a significant indirect effect of social isolation via dietary risk (B = 0.25, SE = 0.08), with a 95% confidence interval for indirect effect not containing zero (95% CI = .11, .38).

Conclusion/Implications: Our findings suggest that the negative impact of social isolation on cognitive health is through its role in dietary habits and practice. Particularly among older immigrants, dietary risk is closely linked with cultural and social aspects, often centered around eating ethnic foods. Their life challenges with language barriers, transportation issues, and financial difficulties also make them reliant on others for meal-related tasks (e.g., grocery shopping and meal preparation). Our result emphasized the importance of addressing dietary risks in cognitive health promotion efforts. Implementing strategies to promote access to meal programs within the ethnic community (e.g., meal delivery services and congregate dining programs) would be beneficial. Furthermore, targeted approaches are essential for older immigrants who are socially isolated to mitigate dietary risks.