New research from the Centre for Healthy Brain Ageing (CHeBA) suggests that high blood pressure treatment should be part of Alzheimer's disease prevention strategies.
Hypertension is the most common risk factor for dementia, affecting an estimated 1.3 billion people worldwide, including over half of all people over the age of 65. Antihypertensive medication is known to help prevent strokes but up to this point there have been few studies investigating whether antihypertensive medication can reduce the risk of Alzheimer's disease, the most common cause of dementia.
Latest research published in the journal Neurology, the medical journal of the American Academy of Neurology, and led by Dr Matthew Lennon from UNSW Sydney's Centre for Healthy Brain Ageing (CHeBA), looked at data from 31,250 individuals across 14 nations, to investigate whether previous hypertension or antihypertensive use modifies Alzheimer's disease risk in those older than 60 years of age.
"Previous trials and longitudinal studies have indicated that ongoing antihypertensive use in late life reduces dementia risk, but the specific impact on Alzheimer's disease and non-Alzheimer's disease risk remained unclear," said Dr Lennon.
"In our new study we found that those with untreated hypertension over the age of 60 had a 42% greater risk of developing Alzheimer's dementia compared to those with treated hypertension. However, if you had a diagnosis of hypertension and were receiving treatment, your risk for Alzheimer's dementia was no different from those without hypertension."
The findings of this study suggest that antihypertensive use should be part of any Alzheimer's disease prevention strategy throughout later life
Dr Matthew Lennon
The study also found that the effect of the antihypertensive medication did not significantly diminish in older participants.
"This is an important result as studies often have difficulty including participants over the age of 80. Our study, incorporating a collaboration of researchers from all around the world and a large number of older participants, indicates that even as people enter their 80s there are still associations between antihypertensive use and reduced risk of Alzheimer's disease."
"Clinicians should consider this when balancing the risks and benefits of stopping medication in older patients" says Dr Lennon.
The study also found that the effect of antihypertensives for Alzheimer's disease were not significantly different between males and females or those from different ethnic backgrounds. Populations in developing countries have been historically underrepresented in medical research and our study importantly included large numbers of participants from Nigeria and the Republic of Congo, amongst other diverse nations.
"The largest growth of dementia and Alzheimer's disease cases over the next few decades is going to come from the developing world and as such it is important that we understand whether prevention strategies that are effective in one nationality or country are similarly effective in others," says Dr Lennon.
This study is part of the research that has emanated from the international COSMIC consortium that currently comprises 57 cohort studies from 39 countries and is supported by a grant from the National Institutes of Health, USA. Professor Perminder Sachdev of CHeBA, UNSW, who leads this consortium added: "Over the next 30 years the number of people living with Alzheimer's disease around the world is likely to more than double to over 130 million people. Hypertension, a common contributor for dementia, may be undiagnosed in over two thirds of patients with the disease."
Treating this often silent but deadly illness will be crucial in tackling the pressing crisis we are seeing with increasing rates of dementia.
Professor Perminder Sachdev
