Relation between central adiposity and cognitive function in the Maine-Syracuse Study: attenuation by physical activity.

BACKGROUND Previous studies have demonstrated a relationship between central adiposity and cognitive function. However, only some of these studies have adjusted for cardiovascular risk factors and cardiovascular disease, and none have also adjusted for physical activity level. PURPOSE The purpose of the study was to examine the association between anthropometric measures of central adiposity (waist circumference and waist/hip ratio) and cognitive functioning with adjustment for cardiovascular disease risk factors and physical activity. METHODS Participants were 917 stroke- and dementia-free community-dwelling adults (59% women) in the Maine-Syracuse Study. The design was cross-sectional. Outcome measures included tests from the Wechsler Adult Intelligence Scale, the Halstead-Reitan Neuropsychological Battery, the Wechsler Memory Scale Revised, and the Mini-Mental State Examination. RESULTS Waist circumference and waist/hip ratio were inversely related to multiple cognitive domains with adjustment for age, education, gender, and number of prior exams. For example, a 20-cm increment in waist circumference was associated with a 0.14 SD decrement in the Global Composite score. These relations were attenuated with adjustment for cardiovascular disease risk factors. However, with further adjustment for physical activity level, only waist circumference remained significantly associated with performance on the Similarities test. CONCLUSIONS Waist circumference and waist/hip ratio are inversely related to cognitive function. Measures of central adiposity predict cognitive function independently of associated cardiovascular risk factors and events; however, the association between central adiposity and cognitive function is attenuated, to a large extent, by adjustment for physical activity level. Physical activity is an important covariate in studies relating measures of central adiposity to cognition.