Functional MR imaging evidence of altered functional activation in metabolic syndrome

MetS is a cluster of risk factors associated with significant cardiovascular morbidity and mortality and diminished cognitive function. Given that little is known about the early signs of brain vulnerability related to persistent metabolic dysfunction, we set out to determine whether cognitively healthy middle-aged individuals with MetS exhibit an altered cerebrovascular response to a cognitive challenge relative to those without MetS.

Forty neurologically healthy adults aged 40-60 years (19 with MetS and 21 healthy controls) performed a 2-back verbal working memory task during fMRI. We compared BOLD responses between the 2 groups in 8 a priori regions of interest previously shown to be associated with the 2-back in patients with cardiovascular disease.

Age, education level, sex distribution, cognitive and emotional functioning, and task performance (accuracy and reaction time) were not different between the groups. Compared with healthy controls, individuals with MetS demonstrated a lower 2-back-related BOLD response in the right superior frontal gyrus, right superior parietal lobule, and left inferior parietal lobule.

This study provides preliminary evidence that cognitively intact middle-aged individuals with MetS exhibit significant alterations in cerebrovascular response to a cognitive challenge. Our results also demonstrate that fMRI may identify early brain changes associated with MetS.