Adiposity and cognitive decline in the cardiovascular health study

Background: Studies relating adiposity to cognition in the elderly show conflicting results, which may be explained by the choice of adiposity measures. Thus, we studied the longitudinal associations of different adiposity measures, fat mass by bioelectrical impedance analysis, body mass index (BMI) and waist circumference (WC), with cognitive performance in the Cardiovascular Health Study. Methods: Cognitive performance was assessed with the modified Mini-Mental State Examination, the Digit Symbol Substitution Test, and a composite of both. We used linear mixed models to estimate rates of change in cognitive function scores associated with adiposity measured at baseline. Results: The final sample was comprised of 2,681 women (57.9%) and 1,949 men (42.1%) aged 73 ± 5.2 and 73.9 ± 5.6 years, respectively. Adiposity was associated with slower cognitive decline in most analyses. Results were similar for fat mass, BMI and WC. Higher fat-free mass was also related to slower cognitive decline. Results were similar in analyses excluding persons with cancer, smokers, and persons with short follow-up, poor self-reported health, or persons with cardiovascular disease. Conclusions: Higher adiposity and higher fat-free mass in the elderly was related to better cognitive performance. This finding was not explained by confounding by preexisting conditions.