The metabolic syndrome, atherosclerosis and cognitive functioning in a non-demented population: The Hoorn Study

Background: The metabolic syndrome (MetS) is associated with cognitive deficits and atherosclerotic vascular disease. We examined whether the relation between the MetS and cognitive dysfunction is mediated by measures of atherosclerosis or the presence of clinically manifest cardiovascular disease. Methods: In 380 individuals (153 with MetS; 60-87 years) from the population based Hoorn Study, measures of atherosclerosis including carotid intima-media thickness (c-IMT), flow mediated dilation (FMD), ankle-brachial index and the presence of clinically manifest cardiovascular disease were assessed at baseline and 7 later years at follow-up. Cognitive functioning (information processing speed, memory, and attention and executive functioning) was assessed at follow-up. The relation between the MetS, atherosclerosis and cognitive functioning was assessed with linear regression analysis. Results: Individuals with MetS showed worse performance on information processing speed (adjusted mean difference z-score +/- SE: -0.22 +/- 0.6; p = 0.01) and attention and executive functioning (-0.32 +/- 0.07; p <0.001), but not on the domain memory. The affected cognitive domains were also associated with measures of atherosclerosis (standardised B (95%CI) c-IMT: -0.14 (-0.24; -0.05); p <0.01; FMD: 0.13(0.02; 0.24),p <0.05) and a history of clinically manifest cardiovascular disease: (-0.29 (-0.47; -0.11); p <0.01). However, the relation between the MetS and cognitive functioning did not change after adjustment for c-IMT, FMD or a history of clinically manifest cardiovascular disease (p > 0.05). Conclusion: In this population based cohort, the relation between the MetS and cognitive dysfunction was not mediated by atherosclerosis or a history of cardiovascular disease. These findings should stimulate future studies to elucidate alternative mechanisms underlying cognitive deficits in individuals with MetS.