Metabolic syndrome over 10 years and cognitive functioning in late mid life: The Whitehall II study

Abstract

Objective: Evidence that the metabolic syndrome is a risk factor for poor cognition is mixed, is mainly focused on elderly population, and it is a rare occurrence that socio-economic factors are adjusted for. We examined this association in late mid life, with particular focus on cumulative effects and the role of socioeconomic circumstances.

Research Design and Methods: Analyses were carried on 4150 white participants from the Whitehall II study. Metabolic syndrome, using the National Cholesterol Education Program Adult treatment Panel III (ATP III) criteria, was assessed three times over the 10-years follow-up (1991-2001). Cognitive function was assessed using a battery of 6 tests at the end of the follow-up.

Results: After adjusting for demographic variables, health behaviours and health status, participants with persistent metabolic syndrome (at least 2 out of the 3 screenings) over the 10-year follow-up had lower cognitive performance than participants who never had metabolic syndrome. No significant differences in cognitive function were observed between participants with non-persistent metabolic syndrome (1 out of the 3 screenings) and those who never had metabolic syndrome during the follow-up. Adjustment for adult occupational position attenuated this association by between 41% and 86%, depending on the measure of cognitive function. Adjustment for education had little effect.

Conclusion: Only persistent metabolic syndrome was associated with lower cognitive performance in late mid life. Adult occupational position, but not education, had a substantial impact on this association; these results highlight the importance of adult socioeconomic circumstances in identifying and targeting risk factors for cognitive ageing.