3 August 2017
Toronto, ON – A new study from Sunnybrook researchers provides evidence that a specific type of treatment for hypertension, or high blood pressure, appears to protect against brain degeneration associated with Alzheimer’s disease, and preserve cognition when compared to other classes of anti-hypertensive medications.
“We know that hypertension is an important risk factor for Alzheimer’s Disease (AD) and small vessel disease in the brain, so we sought to investigate whether different treatments for hypertension, specifically angiotensin receptor blockers (ARBs) and angiotensin converting enzyme inhibitors (ACE-inhibitors), have different effects on cognition and the brain structures that affect and control it,” says Dr. Jodi Edwards, co-lead author of the study and Epidemiology Post-Doctoral fellow at Sunnybrook Health Sciences Centre.
The researchers identified a group of elderly adults both with and without mild cognitive impairment or AD who had exposure to blood pressure medications, from the Alzheimer’s Disease Neuroimaging Initiative (ADNI), a large AD neuroimaging study. From MRI scans of the brain, they looked at total brain tissue volume, volume of the memory structures of the brain (ie. hippocampus) and volume of the white matter tissue of the brain. They also looked at participants’ cognitive performance on tests of memory, language, and executive function and examined whether both brain tissue volume and cognition were associated with different types of high blood pressure treatments.
“Individuals prior to AD who were treated with ARBs showed significantly larger overall brain volumes, larger volumes of tissue in the hippocampus – the area responsible for things like memory – and better performance on tests of memory, language, and executive function than those treated with ACE-inhibitors or other high blood pressure medications,” said Dr. Joel Ramirez, co-lead author and Imaging Research Associate at Sunnybrook.
“In elderly hypertensive adults without AD, ARBs appear to have a greater protective effect on multiple MRI markers of neurodegeneration in the brain – brain structures vulnerable to AD,” says Dr. Sandra Black, senior author of the study and Brill Chair of Neurology at Sunnybrook and University of Toronto. “We suspect this may be because different classes of blood pressure medications have different effects on brain energy metabolism and on how the brain processes amyloid, the toxic protein that builds up in the brain to form amyloid plaques, a hallmark of AD. These findings provide new evidence to suggest that the type of medication used to manage high blood pressure may have important effects on the brain, particularly in elderly adults at risk of cognitive decline and AD. As ACEIs are generally more commonly used in clinical practice, choosing a medication, such as ARBs, that have the same benefits for blood pressure control, but may also have benefits for the brain would be desirable in clinical practice when treating patients with hypertension.”
Published in the August 1, 2017 issue of the Journal of Alzheimer’s Disease, this is one of the first studies to compare the use of anti-hypertensive medications for MRI-derived markers of neurodegeneration or SVD and cognition in elderly adults at risk of dementia. This study was funded by a Catalyst Grant from the Canadian Institutes for Health Research (CIHR) and data was obtained from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) http://adni.loni.usc.edu.
Edwards JD, Ramirez J, Callahan BL, Tobe SW, Oh P, Berezuk C, Lanctôt K, Swardfager W, Nestor S, Kiss A, Strother S, Black SE; Alzheimer’s Disease Neuroimaging Initiative. Antihypertensive Treatment is associated with MRI-Derived Markers of Neurodegeneration and Impaired Cognition: A Propensity-Weighted Cohort Study. J Alzheimers Dis, doi: 10.3233/JAD-170238.
Nadia Norcia Radovini
Sunnybrook Health Sciences Centre
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