The Relationship Between Duration of Metabolic Syndrome and Cognitive Functioning

The metabolic syndrome is defined by ≥ 3 of the following: Elevated blood glucose, triglycerides, waist circumference, and blood pressure as well as low levels of high-density lipoprotein. Research has linked cardiovascular risk factors composing metabolic syndrome with decrements in cognition, which may relate to prolonged metabolic syndrome presence. This project aimed to determine the relationship between metabolic syndrome status over time and cognitive performance, whether this relationship varies by cognitive domain, and assess if metabolic syndrome status across time predicts later cognitive impairment, with further exploration of age, race, gender, income, education, exercise, alcohol, and smoking effects in a racially diverse sample. Subjects included 1,314 individuals for whom archival Dallas Heart Study data for metabolic syndrome were available across two time points, including baseline and follow-up 2-9 years later as well as brief cognitive testing at follow-up, with 137 individuals who had additional cognitive testing and consensus diagnosis of cognitive impairment as part of the University of Texas Southwestern Alzheimer’s Disease Center Dallas Heart/Brain Aging Study. Total Montreal Cognitive Assessment score means were compared with 3 levels of metabolic syndrome status: Presence at 1) baseline and follow-up, 2) only at baseline, and 3) absent at both time points within the overall sample. Comparisons were made within homogenous subsamples grouped by age, gender, race, exercise, and education performed with inclusion of those who met metabolic syndrome criteria at baseline but not follow-up. Covariates included age, education, income, gender, race, smoking, cardio-respiratory fitness, and alcohol consumption when significant (p < .15). The relationship between duration of the syndrome and cognitive functioning was modest, but significant among African American women, African Americans with at least 12 years of education, and men ≥ age 55. Follow-up analyses found that presence of metabolic syndrome at follow-up was related to cognition among African Americans ≥ age 55. Conclusion: Though effects are small, African American race may place an individual at risk of cognitive effects of metabolic syndrome independent of other demographic and lifestyle factors, particularly for women, and reversing the syndrome may mitigate associated decrements in cognitive functioning among some groups.