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Common blood pressure drug does not slow down the progression of more advanced Alzheimer’s

Press release issued: 15 November 2021

New research led by the University of Bristol, has shown the drug losartan, normally used to treat high blood pressure (hypertension), is not effective in slowing down the progression of Alzheimer’s disease (AD) in people with mild-to-moderate disease after 12 months of treatment. However, the drug could still be of benefit if prescribed for longer and if given to people with very early disease. The findings are from the phase 2 multi-centre clinical trial known as RADAR ((Reducing pathology in Alzheimer’s Disease through Angiotensin taRgeting).

The double blinded placebo-controlled randomised trial (where participants and doctors don’t know what treatment people are on) investigated whether losartan, compared with a placebo, could reduce brain volume loss, as a measure of disease progression, in people clinically diagnosed with established AD. 

The research, published in The Lancet Neurology and NIHR Efficacy and Mechanism Evaluation, is the first to evaluate the potential benefit of losartan, an angiotensin receptor blocker, which is a drug commonly used to treat high blood pressure and heart failure, in clinically diagnosed AD using brain imaging as a primary outcome.

Two-hundred and sixty-one people aged 55 years or older diagnosed with AD, who had not been prescribed similar hypertension drugs, and who had capacity to consent, were recruited from 23 UK National Health Service hospital trusts between 22 July 2014 and 17 May 2018.

The 211 eligible participants were then randomly allocated with 105 assigned to receive the study drug, 100 mg of losartan, and 106 to the placebo (an identical looking pill with no active medicine) once a day for 12 months.  From the 197 (93%) participants who completed the study, primary outcome data were available for 171 (81%) participants.

The trial assessed the rate of whole brain shrinkage (i.e. atrophy) on MRI scan compared between participants on losartan and those on placebo. The researchers also examined differences in memory tests, day-to-day quality of life and in a subgroup of participants, changes in levels of vascular damage to the brain as measured by MRI.

The study found that 12-months’ treatment with losartan in patients with clinically diagnosed and established mild-to-moderate probable Alzheimer’s disease did not significantly slow down the progression of AD.

Professor Pat Kehoe, Gestetner Professor of Translational Dementia Research at the University of Bristol, who led the trial, said: "With the current lack of effective treatments for Alzheimer's disease (AD), this is an  extremely disappointing result for participants, patients and researchers alike that losartan, although well tolerated, was not effective in reducing the rate of brain atrophy in people with clinically diagnosed AD in the 12 months it was given, especially after so much encouraging evidence to support the need for this trial.

"However, we cannot exclude the possibility, given other findings that are emerging, that losartan, or similar drugs, given to people earlier and for longer in their development of Alzheimer’s, such as folk with certain types of mild cognitive impairment, might still be protective. 

"It is vitally important we continue to search for effective treatments for AD because with an ageing population there will continue to be many people diagnosed with the disease, which will greatly impact on our already overstretched health and social care costs and resources."

The research team are now exploring options to carry out further studies using losartan or other ways of treating the same biochemical deficits losartan was chosen to address, particularly those that might be possible to target in people with even milder specific impairments that might be indicative of very early signs of developing AD.

The study was funded by an MRC and NIHR partnership created to support the evaluation of interventions with potential to make a step-change in the promotion of health, treatment of disease and improvement of rehabilitation or long-term care.        


'Safety and efficacy of losartan for the reduction of brain atrophy in clinically diagnosed Alzheimer's disease (the RADAR trial): a double-blind, randomised, placebo-controlled, phase 2 trial' by Patrick Gavin Kehoe et al published in The Lancet Neurology [open access]

Losartan to slow the progression of mild-to-moderate Alzheimer's disease through angiotensin targeting: the RADAR RCT’ by Patrick G Kehoe et al published in Efficacy and Mechanism Evaluation

Further information

About the National Institute for Health Research
The mission of the National Institute for Health Research (NIHR) is to improve the health and wealth of the nation through research. We do this by:

  • Funding high quality, timely research that benefits the NHS, public health and social care;
  • Investing in world-class expertise, facilities and a skilled delivery workforce to translate discoveries into improved treatments and services;
  • Partnering with patients, service users, carers and communities, improving the relevance, quality and impact of our research;
  • Attracting, training and supporting the best researchers to tackle complex health and social care challenges;
  • Collaborating with other public funders, charities and industry to help shape a cohesive and globally competitive research system;
  • Funding applied global health research and training to meet the needs of the poorest people in low and middle income countries.

NIHR is funded by the Department of Health and Social Care. Its work in low and middle income countries is principally funded through UK Aid from the UK government.

About the Medical Research Council
The Medical Research Council is at the forefront of scientific discovery to improve human health. Founded in 1913 to tackle tuberculosis, the MRC now invests taxpayers’ money in some of the best medical research in the world across every area of health. Thirty-three MRC-funded researchers have won Nobel prizes in a wide range of disciplines, and MRC scientists have been behind such diverse discoveries as vitamins, the structure of DNA and the link between smoking and cancer, as well as achievements such as pioneering the use of randomised controlled trials, the invention of MRI scanning, and the development of a group of antibodies used in the making of some of the most successful drugs ever developed. Today, MRC-funded scientists tackle some of the greatest health problems facing humanity in the 21st century, from the rising tide of chronic diseases associated with ageing to the threats posed by rapidly mutating micro-organisms. The Medical Research Council is part of UK Research and Innovation.

About North Bristol NHS Trust
North Bristol NHS Trust provides hospital and community healthcare to the residents of Bristol, South Gloucestershire and North Somerset and we are also a specialist regional centre for major trauma, neurosciences, plastics and burns, orthopaedics and renal services.

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