Abdominal myosteatosis is associated with lower processing speed in a multiethnic cohort of older adults.

Background: Prior research linking myosteatosis with cognition in older adults has been conducted in relatively homogenous populations with narrow age ranges. We evaluated if abdominal myosteatosis was associated with processing speed in a multiethnic cohort of middle aged and older adults.

Methods: The sample included 1,268 adults (46-86 years-old, mean 63±9 years, 53 % female, 41 % White, 20 % Black, 14 % Chinese, and 25 % Hispanic), a subset from the Multi-Ethnic Study of Atherosclerosis. Bivariate analyses examined the relationships between abdominal computed tomography-derived muscle density (measure of myosteatosis) at clinical exam 3, Digit Symbol Coding (DSC) performance at clinical exam 5, and cytokine levels from clinical exam 1. Multivariable models were adjusted for demographics, education, general cognition, and further adjusted for other known predictors of dementia: APOE-4, physical activity, diabetes, cholesterol, smoking, and blood pressure. We assessed whether central adiposity, general adiposity, and cytokines modified this association. We tested interactions by ethnicity, sex, and age.

Results: Rectus abdominis myosteatosis was significantly associated with worse DSC (B=-0.247, 95 % CI: 0.098,0.396, p = 0.001) independent of demographics, education, general cognition, and dementia risk factors. Adjustment for central adiposity, and cytokines did not attenuate the associations and interactions by ethnicity, sex, and age were not statistically significant.

Conclusions: Rectus abdominis myosteatosis is associated with worse processing speed in this middle and older aged multiethnic population of men and women, independent of known predictors of cognition. Longitudinal studies should assess the interplay of myosteatosis with other markers of adiposity, inflammation, and circulating mediators and their impact on processing speed.