High blood pressure (BP) is a public health problem worldwide. Nearly three-quarters of older adults (age ~60 years) in the United States have high BP. High BP links to many health problems, like stroke. Drug treatments are typically used in clinics to reduce high BP and the risk of associated health problems. However, these drug treatments may not always benefit brain health. For example, drug treatment may reduce brain blood flow, which may reduce cognitive function in older adults with high BP. Alternatively, reduced brain blood flow may cause high BP due to increased nervous system activity (the so-called "fight or flight response"). Thus, monitoring brain blood flow may help to manage high BP during drug treatment.

It is unknown if brain blood flow and its control will be altered by drug treatment in older high BP patients. Therefore, study team will recruit older adults with high BP, who receive either drug treatment or a placebo for 1 to 2 weeks and will assess brain blood flow, cognitive function, and nervous system control before and after treatment.

Results from this study will provide novel and clinically relevant information on the impact of drug treatment for high BP on brain health. Investigators expect these results will suggest that it is crucial to measure brain blood flow, which may be a therapeutic new target for BP control and brain health.

Inclusion Criteria:

• Older men and women with prehypertension or mild-to-moderate essential hypertension (clinic systolic blood pressure 120-169 and/or diastolic blood pressure 80-109 mmHg).

Exclusion Criteria:

• Any evidence of cardiovascular or pulmonary disease by medical history or by physical examination
• Severe hypertension (systolic BP ≥170 and/or diastolic BP ≥110 mmHg; for safety reasons) or secondary hypertension
• Being on ≥3 antihypertensive agents
• Chronic kidney disease (an estimated glomerular filtration rate >45 mL/min) or renal failure
• Diabetes mellitus (fasting glucose ≥126 mg/dL or 2-hour oral glucose tolerance test, glucose level ≥200 mg/dL) or other systemic illness
• Any history of substance abuse (other than tobacco)
• Current cigarette smokers
• History of gouty arthritis
• Taking hormonal replacement therapy
• Endurance-trained athletes
• Diagnosed Alzheimer's disease and related dementias