Aberrant patterns of default-mode network functional connectivity associated with metabolic syndrome: A resting-state study.

INTRODUCTION: Metabolic syndrome (MetS) is a clustering of three or more cardiovascular risk factors (RF), including hypertension, obesity, high cholesterol, or hyperglycemia. MetS and its component RFs are more prevalent in older age, and can be accompanied by alterations in brain structure. Studies have shown altered functional connectivity (FC) in samples with individual RFs as well as in clinical populations that are at higher risk to develop MetS. These studies have indicated that the default mode network (DMN) may be particularly vulnerable, yet little is known about the overall impact of MetS on FC in this network. METHODS: In this study, we evaluated the integrity of FC to the DMN in participants with MetS relative to non-MetS individuals. Using a seed-based connectivity analysis approach, resting-state functional MRI (fMRI) data were analyzed, and the FC measures among the DMN seed (isthmus of the cingulate) and rest of the brain voxels were estimated. RESULTS: Participants with MetS demonstrated reduced positive connectivity between the DMN seed and left superior frontal regions, and reduced negative connectivity between the DMN seed and left superior parietal, left postcentral, right precentral, right superior temporal and right superior parietal regions, after accounting for age- and sex-effects. CONCLUSIONS: Our results suggest that MetS is associated with alterations in FC between the DMN and other regions of the brain. Furthermore, these results indicate that the overall burden of vascular RFs associated with MetS may, in part, contribute to the pathophysiology underlying aberrant FC in the DMN.

Metabolic risk in older adults is associated with impaired sustained attention.

OBJECTIVE: Metabolic syndrome (MetS), the presence of three or more cardiovascular risk factors, has been associated with subtle and diffuse neural compromise but has not been consistently associated with cognitive dysfunction. Sustained attention is a fundamental cognitive operation that relies on multiple brain networks and is impaired in a broad array of neurologic conditions. We examined whether a well-validated measure of sustained attention would be sensitive to vascular risk, as compared with more standard neuropsychological measures of attention and executive functioning. METHOD: We assessed vascular risk factors (VRFs; blood pressure, waist circumference, cholesterol, glucose, and triglycerides) in 93 middle-to-older aged adults (45-75 years). MetS was defined based on current guidelines from the National Cholesterol Education Program Adult Training Program (NCEP ATP III). Participants were grouped according to number of VRFs: high risk (MetS; 3+ VRFs; N = 32), medium risk (1 or 2 VRFs; N = 35), and low risk (0 VRFs; N = 26). All participants underwent a neuropsychological battery of tests measuring executive functioning. Participants also performed the gradual-onset continuous performance task (gradCPT), a measure of sustained attention. RESULTS: There was a significant main effect of VRF group on sustained attention performance; participants with lower vascular risk were better able to sustain attention. No significant effects were detected on standard neuropsychological tests of executive function. CONCLUSION: Our results suggest that the gradCPT is sensitive to the potentially negative effects of MetS on subtle aspects of neurocognitive functioning. (PsycINFO Database Record (c) 2019 APA, all rights reserved).