Complaints about memory and thinking are common in women as they go through menopause. The female hormone estrogen is important for both the health of both the brain and the blood vessels. In Alzheimer's disease there is damage to the blood vessels in the brain. This study will look at how the loss of the female hormone estrogen affects brain function and the health of blood vessels.

Inclusion Criteria:

• Stages of Reproductive Aging Workshop (STRAW+10) peak or late reproductive stage (-4, -3b or -3a)
• Healthy based on medical history, physical examination and standard blood chemistries
• Normotensive (resting blood pressure <140/90 mmHg)
• Normoglycemia (fasting glucose <110mg/dl and hemoglobin A1c<6.5%)
• Non-smoker (for at least 12 months)

Exclusion Criteria:

• Serum Follical Stimulating Hormone (FSH) >25mIU/mL measured during the first 5 days of the menstrual cycle
• Use of hormonal therapy within the past 3 months
• Use of antihypertensive or lipid-lowering medications
• Pregnant or lactating, or planning to become pregnant during the study period
• Known hypersensitivity to any of the study medications
• Abnormal vaginal bleeding
• History of venous thromboembolism or hormone-sensitive cancer
• History of neurologic disease or major psychiatric illness
• History of diagnosed learning disability or less than high-school education
• Contraindication to Magnetic Resonance Imaging (MRI) scanning
• Depression (Center for Epidemiological Studies - Depression (CESD) score >16)
• Significant cognitive impairment (Mini Mental State Examination (MMSE) score <27)
• Severe osteopenia or osteoporosis (proximal femur or lumbar spine T-score < -2.0)
• Body Mass Index (BMI) >40kg/m2