Relation between the metabolic syndrome, cognitive functioning not mediated by atherosclerosis
MedWire News: Individuals with the metabolic syndrome show reduced cognitive functioning compared with those without the condition, say Dutch researchers.
However, this relationship is not mediated by measures of atherosclerosis or the presence of clinically manifest cardiovascular disease (CVD).
"Our findings do not exclude that the relation between the metabolic syndrome and cognitive dysfunction is mediated by other manifestations of vascular disease, such as cerebral small vessel disease," note Yael Reijmer (University Medical Center Utrecht) and colleagues in the journal Atherosclerosis.
The researchers assessed measures of atherosclerosis, including carotid intima-media thickness (cIMT), flow mediated dilation (FMD), ankle-brachial index, and the presence of CVD at baseline and 7 years later at follow-up in 380 individuals, aged 60-80 years. Cognitive functioning (information processing speed, memory, and attention and executive functioning) was assessed at follow-up in all participants.
The team reports that individuals with the metabolic syndrome (n=153) had a greater cIMT (0.88 vs 0.83 mm, respectively), worse endothelial function (endothelial dependent FMD 3.7 vs 4.7% and nonendothelial dependent nitroglycerin-mediated dilation 9.9 vs 10.7%), and a higher prevalence of ischemic heart disease (43 vs 34%) at baseline than those without the metabolic syndrome.
Furthermore, individuals with the metabolic syndrome showed worse performance at follow-up on the domains of information processing speed (adjusted mean z-score: -0.13 vs 0.09, respectively) and attention and executive functioning (-0.19 vs 0.13) than those without the syndrome. No significant difference in memory performance was observed.
Overall, an increased cIMT was associated with worse information processing speed (standardized B: -0.14) and attention and executive functioning (-0.11), while decreased FMD was associated with worse attention and executive functioning (0.13). The presence of ischemic heart disease or any CVD was associated with worse information processing speed (-0.21 and -0.32, respectively).
However, Reijmer et al found that the relation between the metabolic syndrome and cognitive functioning did not change after adjustment for cIMT, FMD, or a history of CVD, suggesting that atherosclerosis or the presence of clinically manifest CVD does not account for the observed reductions in cognitive functioning in individuals with the metabolic syndrome.
"Whether shared vascular and metabolic risk factors of the metabolic syndrome and atherosclerosis play a role in the development of cognitive deficits remains to be elucidated," write the authors.
They conclude: "Understanding these mechanisms is essential for future intervention studies aiming to reduce the detrimental effect of the metabolic syndrome on the brain."
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By Nikki Withers