The effects of age and metabolic status on cognitive performance

Includes bibliographical references (p. 99-123)Metabolic syndrome is a constellation of vascular and metabolic risk factors that frequently occur in combination, including obesity, raised triglycerides, reduced HDL cholesterol, raised blood pressure, and raised fasting plasma glucose, with the presence of 3 out of 5 risk factors constituting a diagnosis of metabolic syndrome. Metabolic syndrome is associated with increased rates of mortality and increased risk for developing dementia. Changes in brain structure and cognitive functioning have been reported within the literature. However, research examining cognitive performance in individuals with metabolic syndrome is limited, inconclusive and focuses primarily on older cohorts. As such, the effect of metabolic syndrome on cognitive functioning earlier in the lifespan is unclear. This study aimed to investigate cognitive performance in young, middle-aged, and older adults with multiple metabolic and vascular risk factors in a sample of 91 community dwelling participants. The following tests were administered: Dementia Rating Scale, Mini-Mental State Exam, reading subtest from the Wide Ranged Achievement Test-4, Digit Span from the Wechsler Memory Scale-III, Boston Naming Test-2 (BNT), Brief Visuospatial Memory Test-Revised (BVMT-R), California Verbal Learning Test-II (CLVT-II), and several tests from the D-KEFS (Trail Making Test, Verbal Fluency, Design Fluency, and Color-Word Interference Test). As expected, older adults performed more poorly than young and middle-aged adults on measures of information processing speed, attention, memory, and executive functioning. Individuals with metabolic syndrome self-report greater disinhibited eating relative to normal controls. Additionally, individuals with metabolic syndrome performed more poorly on figural memory and figural fluency. These findings suggest that aspects of higher-order, executive functions of visuospatial processing are impaired in metabolic syndrome. Given that individuals with metabolic syndrome had significantly greater self-reported disinihibited eating and performed more poorly on higher-order measures of visuospatial processing (e.g., memory, initiation, planning, multitasking, inhibition), future studies aimed at investigating potential causal relationships between metabolic syndrome, disinhibited eating, and executive dysfunction may provide insight into effective intervention targets to delay or prevent metabolic syndrome. Last, results indicated that incorporating measures of visuospatial abilities in future studies would improve the characterization of cognitive declines in individuals with metabolic syndrom