Abstract
BackgroundAs the understanding of the association between community-level education and dementia is insufficient, this study examined the contextual association of community-level prevalence of low educational attainment on the risk of dementia incidence. With this study, we further explored the potential differences in the aforementioned associations for urban and non-urban areas.MethodsWe analyzed 6 years of prospective cohort data from the Japan Gerontological Evaluation Study, beginning with the baseline data collected between 2010 and 2012, for 51,186 physically and cognitively independent individuals aged ≥65 years (23,785 men and 27,401 women) from 346 communities in 16 municipalities across 7 prefectures. We assessed dementia incidence using available data from the long-term care insurance system in Japan. We dichotomized education years as ≤9 and ≥ 10 years and aggregated individual-level educational attainment as a community-level independent variable. Model 1 covariates were age and sex. Income, residential years, disease, alcohol, smoking, social isolation, and population density were added in Model 2. We conducted multiple imputation to address the missing data. We performed a two-level (community and individual) survival analysis to calculate hazard ratios (HRs) and 95% confidence intervals (CIs).ResultsThe results indicate that the cumulative incidence of dementia during the follow-up period was 10.6%. The mean proportion with educational attainment of ≤9 years was 40.8% (range: 5.1–87.3%). Low community-level educational attainment was significantly associated with higher dementia incidence (HR: 1.04; 95% CI: 1.01–1.07), estimated by 10 percentage points of low educational attainment after adjusting for individual-level educational years and covariates. While the association was significant in non-urban areas (HR: 1.07; 1.02–1.13), there was no association in urban areas (HR: 1.03; 0.99–1.06).ConclusionsOlder people living in communities with low educational attainment among their age demographic develop dementia more often compared with those living in areas with high educational attainment after adjusting for individual-level educational attainment and covariates; the association was pronounced in non-urban areas. Securing education for adolescents as a life course and population approach could thus be crucial in preventing dementia later in life among older people living in non-urban areas.
Highlights
As the understanding of the association between community-level education and dementia is insufficient, this study examined the contextual association of community-level prevalence of low educational attainment on the risk of dementia incidence
There is no cure for dementia, a recent review reported that 40% of dementia cases are preventable; the authors stated that attention should be paid to the following 12 risk factors: low education in early life, hearing loss, traumatic brain injury, hypertension, alcohol consumption, obesity in midlife, smoking, depression, social isolation, physical inactivity, air pollution, and diabetes in late life; the second-highest percentage of these risk factors is less education [4]
We found a statistically significant cross-level interaction term (HR: 0.92; 95% confidence interval (CI): 0.87–0.98 in the crude model) such that individuals with low educational attainment showed 8% lower dementia incidence, estimated by 10 percentage points of increment of a proportion of educational attainment in a community area
Summary
As the understanding of the association between community-level education and dementia is insufficient, this study examined the contextual association of community-level prevalence of low educational attainment on the risk of dementia incidence. Recent studies have begun emphasizing the association between community-level education, rather than the individual level, and dementia and cognitive impairment. Some studies have found associations between area of residence and dementia, such as a reduction in cognitive decline among adults living in urban areas compared with rural areas [7, 8]. A recent U.S study found significantly lower dementia prevalence among adults living in rural areas compared with urban areas over the past few decades, which can be attributed to improvements in educational attainment [9]. Explorations of the relationship between community-level educational attainment and dementia among urban and rural older adults have been insufficient [9, 10]
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