Hair copper concentrations and cognitive performance in Mexican adults aged 50 and older

Abstract Background Previous epidemiological studies have examined the relationship between metal exposures and cognitive function in older adults. However, results regarding copper suggest that both deficient and excessive concentrations can be detrimental to cognitive function. Methods This cross-sectional study analyzed the association between hair copper concentrations and cognitive function in 2,371 Mexican adults aged 50 and older from the 2018 Mexican Health and Aging Study. An adapted version of the Cross-Cultural Cognitive Examination, referred to as the cognitive battery, was used to assess cognitive function. Hair copper concentrations were determined by inductively coupled plasma mass spectrometry and divided into approximately normally distributed (0.05 to 20.95 µg/g, 91% of the cohort) and high-concentration (21.11 µg/g, 9% of the cohort) groups. Results Linear regression revealed a positive association between raw cognitive scores and normally distributed copper concentrations (βstd = 0.04; 95% CI 0.01, 0.07) after adjusting for sociodemographic, health, and environmental factors. Post hoc analysis revealed that socioeconomic status moderates the association between copper and cognitive performance. Conclusions The findings suggest that normally distributed copper concentrations were associated with better cognitive performance, and this effect is specific to the medium socioeconomic level after controlling for covariates. Further studies are needed to confirm the beneficial relationship between copper and cognition and to explore which aspects of socioeconomic status may moderate the effects of copper and other metal exposures.