Date of Award:

5-2008

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition and Food Science

Committee Chair(s)

Ronald G. Munger

Committee

Ronald G. Munger

Committee

Christopher Corcoran

Committee

Heidi J. Wengreen

Abstract

Carbohydrates are a major energy source for the human body and particularly glucose is the only energy source for the brain. Thus glucose metabolism is important to maintain normal brain function. Evidence showed insulin resistance and diabetes are associated with cognitive decline and a large amount of highly processed carbohydrate intake; in other words, a high glycemic load diet, which increases blood glucose faster and insulin demand, is associated with increased risk of insulin resistance and diabetes.

Based on this premise, the hypothesis that a high glycemic load (GL) diet increases the risk of incident Alzheimer’s disease (AD) was examined among Cache County elderly people in Northern Utah. At the baseline survey, 3,831 participants 65 years of age or older completed a food frequency questionnaire (FFQ) and cognitive screening. Observation time to collect the data for incident AD was approximately 10 years. Incident AD was determined by final consensus conference after multi-steps of screening. GL was calculated as the product of carbohydrate intake and glycemic index (GI) and adjusted for energy intake. FFQs from diabetics were considered to be invalid to assess dietary carbohydrates intake and excluded. The analysis was examined separately by gender.

The Cox proportional hazard regression model in survival analysis was used to relate GL to incident AD using a time variable with age of AD onset. There was no association in men but a negative association in women in the unadjusted model. Evidence of confounding by total kcal was apparent in women, particularly in the lowest GL group, which had the highest total kcal mean intake. Finally no association between GL and AD was found after adjustment for education, myocardial infarction (MI), stroke, Body Mass Index (BMI), physical activity, smoking, alcohol use, APOE ε-4 alleles, multi-vitamins use, total kcal, and controlling interaction between GL and total kcal.

The low GL group had unique characteristics in lifestyle factors, macro-nutrients intake, and pattern of food use. The inverse relationship between GL and total kcal may partly be explained by lifestyle factors, particularly alcohol intake. The characteristics of low GL group, current smokers, alcohol users, and their relationship and interaction between total kcal and risk of AD should be explored further.

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