A dissertation defense from Adrianna Isabel Acevedo-Fontánez, Department of Epidemiology, School of Public Health. 

Committee: 
Iva Miljkovic, (dissertation director and academic advisor), Department of Epidemiology 
Joseph Zmuda, Department of Epidemiology 
Emma Barinas-Mitchel, Department of Epidemiology 
Caterina Rosano, Departmnet of Epidemiology 
Sanjay Patel, Department of Medicine, UPMC 

Abstract: 

Brain health and skeletal muscle both decline with age. Skeletal muscle adipose tissue infiltration (myosteatosis), is recognized as a major risk factor for cardio-metabolic diseases and is more prevalent in individuals of African ancestry, which are also at higher risk of Alzheimer's disease and Related Dementia (ADRD). Visceral adiposity is linked to dementia and cognitive decline, yet the relationship between myosteatosis and cognition is not well understood. The role of myosteatosis in cognitive decline and metabolic abnormalities has been studied mainly in White populations, and its significance in middle-aged individuals of African ancestry, independently of cardiometabolic conditions, is unclear. Additionally, the impact of lifestyle risk factors, like sleep health, on skeletal muscle adipose tissues has not been thoroughly explored, especially in African Caribbean populations. Thus, this dissertation fills the gaps by investigating associations of skeletal muscle adiposity, cognitive function, and sleep patterns in adults of African ancestry.

The first dissertation paper explored the novel role of myosteatosis and its association with cognitive decline in a cohort of African Caribbean women. Results showed that myosteatosis was associated with worse performance on the DSST (cognitive test), an early indicator of future dementia risk. The second dissertation paper aimed to replicate these findings in a large representative cohort of Black and White American men and women and assessed this relationship longitudinally. We found that longitudinally, in white women, there was a significant negative association between higher intermuscular adipose tissue resulted in lower cognitive function. The third paper looked at the association between sleep health with general, central, and skeletal muscle adiposity in African Caribbeans. We found that an increase in mean sleep per night was independently associated with lower BMI, lower waist circumference, and higher muscle density in a cohort of African Caribbean men and women with very short sleep duration.

These studies underscore the critical role of myosteatosis and sleep health in cognitive function and adiposity, highlighting the need for targeted interventions to mitigate dementia risk factors and improve overall health. Collectively, these findings advocate for integrated health strategies focusing on muscle health, sleep, and adiposity management to enhance cognitive outcomes and reduce dementia prevalence in diverse populations.