Skeletal muscle adiposity and cognitive decline in a biracial cohort: Insights from coronary artery risk development in young adults (CARDIA) study.

INTRODUCTION: We examined skeletal muscle adiposity (myosteatosis), a risk factor for cardiometabolic diseases, and 5-year cognitive change in White and Black middle-aged men (n = 1080; 41.9% Black) and women (n = 1432; 49.0% Black). METHODS: Abdominal myosteatosis (intermuscular adipose tissue [IMAT, cubic centimeters]) was assessed by computed tomography at Year 25 (Y25). Cognition was assessed (Digit Symbol Substitution Test [DSST], Rey auditory verbal learning test [RAVLT], and Stroop test) at baseline and 5-year longitudinal follow-up (Y30). Multivariable linear regression assessed associations of IMAT with cognitive change. RESULTS: The 5-year change in all cognitive tests was significant: DSST of 2.8% (21.8), RAVLT 2.8% (17.5), and Stroop 6.5% (49.5). A greater Y25 IMAT predicted steeper decline in DSST (β = -0.52, p value = 0.035), but not in Stroop or RAVLT. When stratified by race, a greater IMAT predicted DSST decline only among White participants (β = -0.73, p = 0.044). DISCUSSION: Abdominal myosteatosis may be a novel risk factor for psychomotor speed decline, especially in middle-aged Whites, highlighting the need for targeted prevention strategies. HIGHLIGHTS: Greater myosteatosis predicted slower cognitive processing speed in 5 years. Greater myosteatosis in Whites, but not Blacks, resulted in cognitive decline. Myosteatosis predicted cognitive decline beyond traditional dementia risk factors. Ethnicity might modify links between myosteatosis and cognitive decline. Abdominal CT scans may help identify middle-aged adults at risk for dementia. There is a critical need for more longitudinal studies.