Glycemia but not the Metabolic Syndrome is Associated with Cognitive Decline: Findings from the European Male Ageing Study

Objective: Previous research has indicated that components of the metabolic syndrome (MetS), such as hyperglycemia and hypertension, are negatively associated with cognition. However, evidence that MetS itself is related to cognitive performance has been inconsistent. This longitudinal study investigates whether MetS or its components affect cognitive decline in aging men and whether any interaction with inflammation exists. Methods: Over a mean of 4.4 years (SD ± 0.3), men aged 40-79 years from the multicenter European Male Ageing Study were recruited. Cognitive functioning was assessed using the Rey-Osterrieth Complex Figure (ROCF), the Camden Topographical Recognition Memory (CTRM) task, and the Digit Symbol Substitution Test (DSST). High-sensitivity C-reactive protein (hs-CRP) levels were measured using a chemiluminescent immunometric assay. Results: Overall, 1,913 participants contributed data to the ROCF analyses and 1,965 subjects contributed to the CTRM and DSST analyses. In multiple regression models the presence of baseline MetS was not associated with cognitive decline over time (p > 0.05). However, logistic ordinal regressions indicated that high glucose levels were related to a greater risk of decline on the ROCF Copy (β = -0.42, p < 0.05) and the DSST (β = -0.39, p < 0.001). There was neither a main effect of hs-CRP levels nor an interaction effect of hs-CRP and MetS at baseline on cognitive decline. Conclusion: No evidence was found for a relationship between MetS or inflammation and cognitive decline in this sample of aging men. However, glycemia was negatively associated with visuoconstructional abilities and processing speed.