Global Associations of Sodium Intake With Dementia Prevalence From 2010 to 2021 by Sex: A Longitudinal Ecological Study

Objective Dementia is a major global health challenge, and its prevalence differs according to sex. Dietary sodium intake is considered a modifiable risk factor of dementia. However, the sex-related associations between sodium intake and dementia prevalence based on global data have not been examined. Therefore, this ecological study aimed to analyze the cross-sectional and longitudinal association between sodium intake and dementia prevalence by sex from 2010 to 2021 with the aim of comprehensively elucidating the relationship between sodium intake and dementia. Methods This longitudinal ecological study analyzed data from 151 countries with populations exceeding one million for which relevant data were available (totaling 1,812 country-year observations) to examine associations between baseline (2010) sodium intake and the 12-year trajectory (2010–2021) of dementia prevalence. Data on national-level estimated average habitual sodium intake, dementia prevalence, and covariates were obtained from internationally available databases. A generalized linear model controlled for all available covariates in this study was used for the cross-sectional model in 2010, and a linear mixed model controlled for all available covariables in this study was used for longitudinal analysis from 2010 to 2021. The risk ratio (RR) was estimated based on the difference between the logarithms of sodium intake and dementia prevalence. Results In the 2010 cross-sectional analysis and 2010–2021 longitudinal analysis, estimated national-level average habitual sodium intake was positively associated with dementia prevalence in both men and women. At a national-level estimated average habitual sodium intake of 4.0 g/day, the RR (95% CI) for dementia prevalence, relative to the reference, was 1.09 (1.03–1.16) for men and 1.07 (1.00–1.13) for women compared to the reference. Five countries (3.3%) had sodium intake of ≥4.0 g/day for both men and women. Conclusions Higher sodium intake is associated with higher sex-stratified dementia prevalence worldwide compared to lower sodium intake.