Studying the Effects of Antihypertensives on Individuals at Risk for Alzheimer's

Overview

Angiotensin converting enzyme inhibitors (ACE-I) are a group of blood pressure-lowering medicines. Some studies suggest that ACE-I, such as ramipril, may help prevent Alzheimer's disease (AD). The purpose of the research is to see how ramipril affects a substance in the body called beta-amyloid. Beta-amyloid is found in the brain and in the liquid around the brain and spinal cord. High amounts of beta-amyloid may be associated with a greater risk of getting Alzheimer's disease. This study will see if ramipril can lower the amount of beta-amyloid in the spinal fluid. This study will also see if ramipril affects blood vessel function and memory and thinking. The investigators hope that future studies will show whether ramipril might prevent memory loss and decrease the chance of developing Alzheimer's disease.

High blood pressure (BP) in midlife is predictive of Alzheimer's disease (AD) in later life. Similarly, reductions in BP are associated with protection against AD. Treatment with antihypertensive medications, specifically angiotensin converting enzyme inhibitors (ACE-I) such as ramipril, is associated with up to a 55% reduction in the prevalence of AD, suggesting a potentially promising role for ACE-I in the prevention of AD. It is unknown however 1) whether ACE-Is will have the same effect on Cerebrospinal fluid (CSF) Aβ levels in humans as in animal models 2) whether ACE-Is induce changes associated with vascular function (i.e. levels of CSF angiotensin converting enzyme (ACE) and peripheral endothelial function) and 3) whether there are interactions between ACE-I-induced changes in CSF Aβ, CSF ACE and indices of vascular function. One mechanism by which antihypertensives may protect against AD is via Aβ neuropathology. In order to better understand the mechanisms through which ACE-I may modify CSF Aβ and possibly AD risk, we propose a randomized, double-blind, placebo-controlled pilot clinical trial, enrolling 20 middle-aged (age range 40 - 65 years), mildly hypertensive (between 130 - 160 mmHg mean systolic and between 85 - 100 mmHg mean diastolic) participants, who are adult children of an individual with AD. The main objective of this trial is to examine the effects of the ACE-I, ramipril, on 1) CSF Aβ levels 2) CSF ACE levels and 3) peripheral endothelial function as measured by brachial artery flow-mediated vasodilation (FMD) and aortic augmentation index (AAIx), in middle-aged adults with mildly elevated BP, who are at increased risk of developing AD.