All ETDs from UAB

Advisory Committee Chair

Suzanne Judd

Advisory Committee Members

Paula Chandler-Laney

Barbara Gower

George Howard

Virginia Wadley

Document Type

Dissertation

Date of Award

2016

Degree Name by School

Doctor of Philosophy (PhD) School of Health Professions

Abstract

As life expectancy continues to increase and the number of elderly Americans rises, public health initiatives are seeking to identify modifiable risk factors to preserve cognitive function and increase quality of life in advanced ages. The primary objective of this dissertation was to investigate dietary patterns, carbohydrate consumption, and insulin resistance as modifiable risk factors that may contribute to the development of cognitive impairment and cognitive decline. Three separate studies were performed in the REasons for Geographic And Racial Differences in Stroke study, a prospective cohort containing 30,239 black and white participants. Cognitive impairment was defined using the Six-Item Screener. Verbal learning, memory, and executive function were assessed using the word list learning, word list delayed recall, and animal fluency test. Dietary intake was measured by the Block98 food frequency questionnaire (FFQ). Principal component analysis was utilized to derive dietary patterns and estimates for glycemic index (GI), glycemic load (GL), and available carbohydrate intake (CHO) were assigned when analyzing the FFQs. The homeostatic model assessment of insulin resistance was used to estimate insulin resistance. In a cohort of participants without stroke at baseline, we found that the alcohol/salads dietary pattern was associated with lower odds of incident cognitive impairment and higher verbal learning, memory, and executive function. The plant-based pattern was associated with higher verbal learning and memory, and the Southern pattern was associated with lower verbal learning, memory, and executive function. Higher GL and CHO were associated with higher odds of incident cognitive impairment. Additionally, we observed a significant racial difference in the associations between both GL and CHO and change in verbal learning over time. Lastly, an inverse association was observed between insulin resistance and incident cognitive impairment. Although no significant racial difference was detected, the association was predominantly present in black participants. In conclusion, dietary patterns consisting of plant-based foods, alcohol intake, lower GL, and lower CHO may contribute to more favorable cognitive outcomes in advanced ages. The relationship between insulin resistance and cognitive outcomes is less clear, and further studies are warranted to elucidate potential racial differences in the effects of insulin resistance on cognitive health.

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