Do Blood Pressure Medications Prevent Alzheimer's?
While the cure for Alzheimer’s disease still manages to elude us our knowledge of strategies to prevent or delay its onset are developing steadily. There appear to be a number of risks that increase our chances of developing Alzheimer’s, one of which is high blood pressure.
High blood pressure has the effect of narrowing and tightening the small blood vessels in the brain. This can lead to problems with thinking and memory so anything that can reduce blood pressure is likely to have benefits. However, middle-aged people with high blood pressure are also more likely to have Alzheimer’s biomarkers in their cerebral spinal fluid. A biomarker can be thought of as something within the body that indicates a known characteristic of a disease. In Alzheimer’s disease biomarkers commonly known as plaques and tangles are more likely in people with high blood pressure. In one study, reported in the medical journal Neurology, it was reported that for every 10 point rise in blood pressure, the average level of certain Alzheimer’s biomarkers increased. Curiously, the link was only found in people between the ages of 55 to 70, but not in people over that age.
Everyone recognizes the value of scientific enquiry, no more so than with medical science, but even here a number of useful discoveries have been made completely by accident. It was just over a decade ago that researchers testing a drug for angina discovered unexpected side effects that would later be developed into the drug Viagra. But such happy accidents go way back. Where would we be without Alexander Fleming’s keen eye and scientific curiosity that led to the development of penicillin? Fleming was actually studying food poisoning but noticed a patched of blue-green mold and, well the rest is history.
Unfortunately the latest investigations don’t fall as neatly into the same category, but they do move us forward. A research team at John Hopkins University School of Medicine were originally interested in whether the herb gingko biloba could reduce the risk of Alzheimer’s. As it happens the answer was no, but the team had collected data on a variety of issues, such as the use of diuretics and other medications and discovered that some of the most commonly used medications for control of high blood pressure appeared to halve the risk of developing Alzheimer’s. Earlier this year a team from Bristol University in the UK, reported that Losartan, also used in the treatment of high blood pressure, had the effect of slowing the progression of Alzheimer’s.
But the puzzle for scientists remains. If reductions in blood pressure alone resulted in risk reduction then all blood pressure medications should show similar results, but they don’t. So the question is do only certain types of blood pressure medication reduce the risks, or is something else going on that has yet to be uncovered?
S. Yasar, J. Xia, W. Yao, C. D. Furberg, Q.-L. Xue, C. I. Mercado, A. L. Fitzpatrick, L. P. Fried, C. H. Kawas, K. M. Sink, J. D. Williamson, S. T. DeKosky, M. C. Carlson. ‘Antihypertensive drugs decrease risk of Alzheimer disease: Ginkgo Evaluation of Memory Study.’ Neurology, 2013; 81 (10): 896