A longitudinal study of the impact of the metabolic syndrome on cognition and brain volumes in normal aging
Concurrent with the increased prevalence of obesity in the United States, a significant portion of older adults are increasingly at risk for developing metabolic dysfunction including insulin resistance or impaired glucose tolerance, dyslipidemia, hypertension, and abdominal obesity. These metabolic abnormalities tend to cluster together, forming what is known as metabolic syndrome. Metabolic syndrome is widely considered a "pre-disease" state associated with development of cerebrovascular disease and dementia. Several studies have proposed links between components of metabolic syndrome and neurocognitive and brain dysfunction; however, few studies have examined the additive effect of the cluster of risk factors that comprise the syndrome. This study used the National Cholesterol Education Program criteria, modified to be inclusive of insulin resistance, in a baseline and follow-up design to compare a group of 58 middle-aged and elderly adults with metabolic syndrome to 64 age-matched controls on cognitive performance. Additionally, magnetic resonance imaging (MRI) brain volumes were derived on a subset of participants using Voxel-based Morphometry and Automated Anatomical Labeling techniques. Metabolic syndrome was associated with significantly reduced performance on standard neuropsychological tests of declarative memory, and exhibited strong effects for reduced performance on tests of attention and working memory. Metabolic syndrome was also significantly associated with reduced total brain volume, reduced gray matter volume, and reduced volumes in areas in regions of the temporal and prefrontal regions that have established associations with declarative memory. Robust longitudinal effects associated with metabolic syndrome were seen in declarative memory, attention and working memory, and total brain volume. Unlike any published study to date, the results provide novel evidence that the metabolic syndrome is associated with smaller total brain volume and total gray matter volume. Further, participants with metabolic syndrome performed worse on declarative memory tests and had smaller volumes in prefrontal and temporal lobe areas associated with declarative memory.
Hassenstab, Jason, "A longitudinal study of the impact of the metabolic syndrome on cognition and brain volumes in normal aging" (2008). ETD Collection for Fordham University. AAI3353770.