Dementia and lower blood pressure in Latin America, India, and China: a 10/66 cross-cohort study.

OBJECTIVE: To study the relationship between dementia and blood pressure (BP) in 8 low- and middle-income countries.
METHODS: In identical cross-sectional surveys of older adults (aged 65 years and older) conducted in Cuba, Dominican Republic, Peru, Venezuela, Mexico, Puerto Rico, China, and India (n = 15,746), we measured systolic and diastolic BP and used the 10/66 prevalidated algorithms to adjudicate dementia diagnosis and quantify dementia severity (Clinical Dementia Rating [CDR]).
RESULTS: BP levels, dementia prevalence, and participants' sociodemographic and health characteristics varied across sites. In fixed-effect meta-analyses of site-specific linear regression coefficients adjusted for potential confounders, dementia and CDR were cross-sectionally associated with lower systolic BP (β = -1.7, 95% confidence interval [CI]: -2.8, -0.6; and β = -1.1, 95% CI: -1.5, -0.7) and diastolic BP (β = -0.4, 95% CI: -1.1, 0.2; and β = -0.4, 95% CI: -0.7, -0.2). Associations were heterogeneous across sites for both dementia (I(2) < 47%) and CDR (I(2) < 75%), and were strongest in Cuba, where prevalence of hypertension was highest. Results were robust to alternative model specifications that accounted for hypertensive status, antihypertensive treatment, and leanness (i.e., smaller waist circumference).
CONCLUSION: The association between dementia and lower BP was heterogeneous across geographically diverse samples, strongest where prevalent hypertension was highest (in Cuba), and relatively small compared with that found in Western settings. Both the mechanisms and the extent to which different levels of lifetime hypertensive disease explain this heterogeneity remain uncertain. However, because rapid increments in both dementia and hypertension are predicted in low- and middle-income countries, closer monitoring is warranted.