Cardiometabolic Risk and Cognitive Function Decline in U.S. Elderly

Purpose Several studies have reported an association between cardiometabolic risk (CMR) and cognition and dementia, but these studies have been small, and large nationally representative studies are lacking. The present study aimed to examine this association using data from the cross-sectional studies of National Health and Nutrition Examination Surveys (NHANES 1999–2002.) Methods A total of 2238 participants aged ≥65 (M: 1084 and F: 1154) who had CMR and cognitive function (CF) measurements were included in the study. CMR factors included the following seven components: BMI ≥30 kg/m2; low HDL (<35 mg/dl for males and <38 mg/dl for females); LDL ≥130 mg/dl; triglycerides ≥150 mg/dl; hypertension; smoking; and physical inactivity. CF was measured by a 2-minute timed Digit Symbol Substitution Test (DSST), which is an executive function measure from the Wechsler Adult Intelligence Test. CF decline was defined as DSST score <38 (the median score in the study population). Results Mean (SD) DSST scores w ere 37.3 (17.2) and 40.1 (18.3) in males and females, respectively. Forty-one percent of males and 47% of females had three or more of the seven CMR factors, and 19% of males and 21% of females had four or more components. Age-adjusted logistic regression analyses indicated that people with ≥3 components of CMR were significantly associated with CF decline. The odds ratios (OR) for CF decline, compared to those with <3 CMR factors, were 1.36 (95% CI 1.04–1.79) in males and 1.40 (95%CI 1.07–1.84) in females. The ORs for CF decline among those with ≥4 CMR components, compared to <4 CMR components, were 1.56 (95%CI 1.11–2.21) in males and 1.81 (95%CI 1.30–2.52) in females. This association remained significant in females (OR: 1.59; 95% CI 1.09–2.32) after multi-adjustment for race, education, history of heart disease, stroke, and diabetes. Among the seven components of CMR, physical inactivity and low HDL levels had the strongest associations with CF decline in both genders. Conclusion Although cross-sectional associations do not necessarily imply causality, the present study extends our understanding of CMR in relation to CF, and indicates useful avenues for further study on the prevention of CF decline in the elderly.