Association of Urinary Perchlorate and Thiocyanate With Cognitive Function in Older Adults: A Cross-Sectional Study

It is well-known that perchlorate, nitrate, and thiocyanate are thyroid-disrupting chemicals. Evidence regarding the cognitive correlates of thyroid-disrupting anions in older adults remains scarce, particularly in population-based studies assessing multiple cognitive domains. Our study aimed to explore the associations between urinary levels of perchlorate, nitrate, and thiocyanate and cognitive function.

Participants were obtained from the National Health and Nutritional Examination Survey (NHANES). Urinary levels of perchlorate, nitrate, and thiocyanate were measured by ion chromatography coupled with electrospray tandem mass spectrometry. Cognitive function was evaluated using the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) test, the Animal Fluency Test (AFT), and the Digit Symbol Substitution Test (DSST). Logistic regression analyses were conducted to examine the association between urinary levels of the chemicals and cognitive function.

A total of 993 adults were included with a mean age of 69.5 ± 6.6 years. In multivariable-adjusted logistic regression models, urinary perchlorate was inversely associated with low cognitive function evaluated through the AFT [OR: 0.78; 95% CI (0.63, 0.96); p < 0.05], and urinary thiocyanate was negatively related to low cognitive function assessed by CERAD [OR: 0.70; 95% CI (0.50, 0.97); p < 0.05] and AFT [OR: 0.69; 95% CI (0.50, 0.94); p < 0.05].

A relative low urinary perchlorate and thiocyanate were associated with low cognitive function. Higher levels of perchlorate and thiocyanate may be inverse cross-sectional associations in cognitive function.