Association between whole blood essential trace elements and cognitive function in the elderly

BACKGROUND Essential trace elements (ETEs) are important for keeping nervous system function. The evidence of associations between ETEs and cognitive function among the elderly was limited. Therefore, we aimed to investigate the individual and joint association between ETEs and cognitive function among the elderly. METHODS An elderly population from Yiwu cohort in China was available for this study. Whole blood chromium (Cr), manganese (Mn), copper (Cu), and selenium (Se) concentrations were measured by inductively coupled plasma mass spectrometry (ICP-MS). Cognitive function was assessed using the Mini-Mental State Examination (MMSE), consisting of five specific-cognitive domains of orientation, registry, attention and calculation, recall, and language and praxis. Linear regression, restricted cubic spline (RCS) analysis, and Bayesian kernel machine regression (BKMR) were performed to explore the individual and joint associations between ETEs and cognitive function. RESULTS Linear regression showed that high-level Cr was positively associated with MMSE score compared to the lowest quartile, especially with recall. Further RCS analysis found an inverted-U-shaped association between Cr and MMSE score. Se was positively associated with MMSE score and particularly with registry. BKMR model showed that ETEs mixture was positively associated with cognitive function, and Se was the most important contributor within the mixture. Therefore, Se demonstrated a positive additive effect on the associations for other ETEs with cognitive function. CONCLUSIONS Low and high levels Cr were associated with poor cognitive function, indicating that exploring an appropriate range of Cr concentration is important. Se was positively associated with cognitive function and was the most important contributor to the association between ETEs mixture and cognitive function. Moreover, Se presented the additive effect for other ETEs. Thus, it should be considered the joint effect of ETEs mixture. Our findings provided the evidence to protect cognitive function by supplementing ETEs. KEYWORDS: Cognitive function; Essential trace element; The elderly; BKMR.