Associations Between Hydration Status and Executive Function in Middle-Aged and Older Adults: Findings from the Nationally Representative Health and Retirement Study

The purpose of the current study is to examine the association between hydration status and cognitive function in middle-aged and older adults, drawing from a large, nationally representative sample in the United States and using a comprehensive set of executive function performance measures. We utilized data from the Health and Retirement Study to conduct twelve, three-stage hierarchical regressions on hydration status and executive function performance of older adults. Cognitive performance scores on the Trail Making A, Symbol Digit Modalities, and Letter Cancellation tests significantly differed by hydration status, and these outcomes follow a curvilinear pattern, such that performance scores are lower for those who are hyper-hydrated or dehydrated relative to those who are euhydrated or near-dehydration. Our study's findings are consistent with prior studies examining the impact of serum osmolarity on cognitive performance. Specifically, a curvilinear pattern was associated with speed of processing tests of executive function. Overall, hydration status is associated with curvilinear patterns of performance on executive function measures, specifically Trail Making A, Symbol Digit Modalities, and Letter Cancellation Tests.