APOE Genotype and Diet Influences on Alzheimer's Biomarkers

The purpose of this study is to examine how the risk gene for Alzheimer's disease APOE epsilon 4 (E4) influences acute cognitive responses to different types of meals. The rationale for this study is that we know that a diet high in saturated fat and high glycemic index foods (HIGH diet) is a risk factor for Alzheimer's disease (AD). However we have found paradoxically that a Western style HIGH diet acutely improved cognition in APOE E4 carriers, but worsened cognition in E4 non-carriers. This experiment will examine mechanisms that underlie this differential response between E4 carriers and non-carriers. We will enroll older adults who do not have dementia, half of which will be E4 carriers and the other half will be non-carriers. Both groups will contain equal numbers of men and women. These individuals will undergo two experiments in which they eat either a high or a low fat meal, and then after the meal will undergo several tests. The outcome measures include blood measures of metabolic markers, cognitive tests that are known to be sensitive to changes even after a single meal, and spinal fluid measures of Alzheimer's biomarkers such as beta-amyloid, as well as spinal fluid levels of lipids, glucose and insulin. This study will allow us to test whether high and low fat meals acutely affect cognitive and Alzheimer's biomarkers, and if those changes depend on APOE genotype or gender. It is our hope that this work will contribute to our broader understanding about the risks of diet and AD, to help us understand more about how to prevent and treat this devastating neurological disease.