To examine independent associations of social risk factor domains with dementia among Medicare beneficiaries aged 65 and older.

Dementia is a leading cause of disability in older adults. In recent years, social factors have been increasingly recognized as contributors to accelerated brain aging. Understanding these associations may inform the development of evidence-based social interventions as preventative strategies against cognitive decline.

We followed the STROBE guidelines for cross-sectional studies and utilized National Health Interview Study data from 2019-2022. The primary exposure variables included five social risk factor domains: economic instability, educational deficits, food insecurity, social isolation, and inadequate access to healthcare. The primary outcome was any past diagnosis of dementia, including Alzheimer's disease. Logistic regression models assessed associations between each social risk domain and dementia, adjusted for age, race, and comorbidities (obesity, depression, anxiety, stroke, hypertension, coronary heart disease, myocardial infarction, asthma, COPD, cancer, diabetes, liver disease, kidney disease, and arthritis). All risk domains were included in the same regression model. Analyses were weighted using the ‘survey’ package in R (version 4.3.1), and statistical significance was set at P<0.05.

This study included 31,664 unweighted participants (weighted n=51,609,990). Average age was 74.0 years (SE=0.046), with 55.3% female, 76.8% non-Hispanic White, 9.1% non-Hispanic Black, 4.5% non-Hispanic Asian, and 8.1% Hispanic participants. Fully-adjusted models showed economic instability (OR 1.31; 95% CI [1.10, 1.56], p < 0.01), educational deficits (OR 1.90; 95% CI [1.55, 2.32], p < 0.001), and social isolation (OR 2.87; 95% CI [2.46, 3.33], p < 0.001) were independently associated with increased odds of dementia. Food insecurity and access to healthcare were not significantly associated with dementia.

Policy initiatives addressing economic instability, educational deficits, and social isolation may reduce the risk of dementia in older adults. Further research is needed to investigate the potential mechanisms through which social factors impact cognitive aging.