Abdominal Myosteatosis and Cognitive Decline in a Biracial Cohort: Insights from CARDIA Study

Objective: Skeletal muscle fat infiltration (myosteatosis) increases with age and is an emerging risk factor for dementia. We aimed to determine the association between myosteatosis and cognitive decline among middle-aged White and Black Americans. Methods: Data were on men (n=1,080; 41.9% Black) and women (n=1,432; 49.0% Black) from the CARDIA study. CT-measured abdominal intermuscular fat (IMAT) volume was assessed at baseline. Cognition was assessed by Digit Symbol Substitution (DSST), Rey Auditory Verbal Learning (RAVLT), and Stroop Test at baseline and 5-year follow-up. Multivariable linear regression was used to assess associations of IMAT with cognitive change. Results: , 5-year change in DSST of -2.8% (21.8), RAVLT 2.8% (17.5) and Stroop 6.5% (49.5). Greater IMAT was associated with steeper DSST decline (β =-0.52 points per SD, p-value=0.035), but not with Stroop or RAVLT. Stratified by race, greater IMAT predicted DSST decline among White (β =-0.73, p =0.044), but not Black (β =-0.44, p =0.195), participants. Conclusions: Abdominal myosteatosis may be a novel risk factor for decline in psychomotor speed, especially in middle-aged Whites. Further research on mechanisms, including metabolic mediators, is warranted to understand myosteatosis's role in mid-life cognitive decline.