APOE Genotype and Diet Influences on Alzheimer's Biomarkers

Inclusion Criteria: 1. Written consent is signed and dated by the subject. 2. Subject is at least 55 years of age or older, and if female, must be post-menopausal for at least one year, or be one year out from a hysterectomy. 3. Able to read and understand English 4. Be free of dementia, and able to cognitively and physically give informed consent. 5. In the opinion of the investigator, the subject will be able to complete the study procedures. \- Exclusion Criteria: 1. Diabetes: Known type 1 or Type 2 diabetes, currently taking diabetic medications or insulin, and/or fasting blood glucose ≥ 126 as per the 2009 American Diabetes Association guidelines. Remote use of diabetic agents, or a history of gestational diabetes, is ok. 2. Liver and kidney disease: Active liver disease will be excluded. Also excluded are elevations in liver function tests of SGOT (AST) and/or SGPT (ALT) \> 1.5 times the upper limit of normal. Active renal disease (Stage IV or V chronic kidney disease) will also be excluded. 3. Lipid abnormalities: Diagnosis of hyperlipidemia or hypertriglyceridemia requiring statin, bile acid resins, fibrate medications, and/or high dose niacin will be excluded, as these medications may interfere with the study outcomes. If subjects are on omega-3 fatty acids, low dose niacin, or other alternative/herbal remedies such as red yeast rice, they can be enrolled if they agree to stop the medication during the study period. Also excluded are significant cholesterol abnormalities as defined by the Adult Treatment Panel III classification: LDL cholesterol ≥190 mg/dL, total cholesterol ≥240 mg/dL, or triglycerides \> 200. HDL levels outside of the typical range are ok. 4. Dementia and cognitive impairment: Known diagnosis of dementia, use of dementia medications, or identification of dementia during the baseline visit, will be excluded. Also excluded are other significant neurologic diseases which affect cognition, such as recent stroke, recent severe head injury, or advanced Parkinson's disease. Mild cognitive impairment with no functional deficits is ok. 5. Contraindications to lumbar puncture: Those with medical conditions that preclude a lumbar puncture such as an intracranial tumor, lower spinal hardware, or use of anticoagulation, will be excluded. Daily aspirin for prevention is ok. Use of NSAIDS is ok as long as participant uses them as needed rather than daily, and is able to discontinue these agents two days prior to the LP procedures. 6. Significant medical illnesses: Illnesses which would cause a hardship on the participant to attend study visits and undergo a lumbar puncture. This includes uncontrolled severe hypertension, unstable angina or cardiovascular disease, moderate pulmonary disease (COPD), and Class III-IV congestive heart failure (CHF). 7. Active malignancy undergoing treatment with chemotherapeutic or radiation treatments. Remote history of treated cancer is ok, as long as current cognition and digestion are not affected 8. Treatment with hormones: Use of estrogen, testosterone, and continuous corticosteroid replacements will be excluded, as these may have effects on study outcomes. Women must be post-menopausal for at least 1 year before enrolling in the study, or be one year out from a hysterectomy. Women who use hormone replacement therapy for symptomatic menopause can be enrolled, if they agree to discontinue the medication four weeks before the first meal and then throughout the study. Transgendered subjects can be included in the study, provided that they are not taking sex steroids. 9. Psychiatric disorders: Subjects who report active untreated major depression, psychosis, or mania, or who present with those symptoms at the baseline visit, will be excluded. Psychiatric conditions such as post-traumatic stress disorder (PTSD), depression, and anxiety which are stable and treated with medication or therapy are ok. 10. Major digestive disorders including inflammatory bowel diseases, irritable bowel syndrome, and celiac disease. History of surgical procedures which may affect the absorption of meals, such as any weight loss surgery such as gastric bypass or banding, or small intestine resection. Acid reflux is allowed if participant is on a stable medication regimen. 11. Food allergies and intolerances: Those subjects allergic to the ingredients of the meals will be excluded. Also excluded are medical conditions requiring strict adherence to a particular diet, such as celiac disease or phenylketonuria. 12. Alcohol use: While they are in the study, subjects will be asked to limit their alcohol intake to two drinks per day or less for men, or one drink per day or less for women, due to alcohol's effects on lipid biochemistry and the study outcomes. Subjects who are unable or unwilling to meet these criteria will not be enrolled. \-