Association between Iodized Salt Intake and Cognitive Function in Older Adults in China.

ABSTRACT

OBJECTIVES: To investigate the association between iodized salt intake and cognitive function in older adults. DESIGN: A cross-sectional study. SETTINGS Individuals from the Zhejiang Major Public Health Surveillance Program (ZPHS). PARTICIPANTS: Data of 10,217 participants (including 4,680 coastal residents and 5,537 inland residents) aged ≥ 60 years were analyzed. MEASUREMENTS Salt intake was evaluated using a questionnaire, and participants were stratified into the following three groups iodized salt, non-iodized salt, and mixed salt. Cognitive function was assessed through the Mini-Mental State Examination and defined using education-specific cut-off points. Logistic regression models controlling for an extensive range of potential confounders were generated to examine the association between salt intake and cognitive function among all participants. RESULTS: Data from 10,217 participants with a 16.1% prevalence of cognitive impairment were analyzed. Compared with non-iodized salt intake, consumption of iodized salt was inversely associated with cognitive impairment (odds ratio [OR], 0.410; 95% confidence interval [CI], 0.351-0.480; P < 0.001) in all participants after multivariable adjustment. An association between iodized salt intake and cognitive impairment was observed in coastal (OR, 0.441; 95% CI, 0.340-0.572; P < 0.001) and inland residents (OR, 0.569; 95% CI, 0.439-0.738; P < 0.001). Despite the insufficient sample size, the results for individuals consuming mixed salt suggested an inverse association between mixed salt intake and cognitive impairment among coastal residents (OR, 0.598; 95% CI, 0.405-0.885; P = 0.010) after multivariable adjustment. CONCLUSION: Our results indicate that iodized salt intake may reduce the risk of cognitive impairment in older adults living in coastal or inland areas, and the protective effect of iodized salt intake is greater in coastal areas than in inland areas.