People with Alzheimer's disease are already helping with a ground-breaking government-funded trial led by academics from the Universities of Bristol, Cambridge, Queen's University Belfast and University College London, and hosted by North Bristol NHS Trust, but even more people are needed to take part in the study.

The research study, known as RADAR (Reducing pathology in Alzheimer's Disease through Angiotensin taRgeting) is investigating if a drug normally used to treat high blood pressure (hypertension) has additional properties that could slow down the progression of Alzheimer’s disease (AD) in people with and without hypertension. Approximately almost half a million people in the UK have Alzheimer's disease, which is the most common form of dementia that affects and memory and brain function in older individuals.

As part of the Prime Minister's Challenge on Dementia, funding of nearly £2 million was awarded by the Efficacy and Mechanism Evaluation (EME) Programme, an MRC and NIHR partnership.

RADAR is a multi-centre clinical trial that is investigating if losartan, a blood pressure drug that first became available in 1995, can complement current treatments for AD. The researchers believe losartan can slow down the progression of AD by improving brain blood flow and altering chemical pathways that cause brain cell damage, brain shrinkage and memory problems in AD.

Recruitment for the RADAR trial, now open at 23 sites across England, Scotland and Northern Ireland, has been extended across the until the end of February 2018 and with 140 participants already taking part in the study, the researchers need another 90 people to sign up to complete the study.

The RADAR study is a double-blinded placebo-controlled randomised trial, meaning that some participants will be randomly assigned to receive either the study drug, losartan, or a placebo (an identical looking pill with no active medicine) once a day for 12 months. Nobody, including the doctors and nurses involved, will know until the study is analysed who received which. This is one of the most powerful study designs available.

Initially all participants who are eligible to enrol will receive two weeks of losartan and then two weeks of the placebo to ensure they are happy taking the medication before entering the year-long trial.

People with Alzheimer's disease who have high or normal blood pressure can take part if they meet certain eligibility criteria and RADAR will use brain imaging to measure whether losartan reduces the rate of brain shrinkage normally occurs in AD. It will also be using what are standard questionnaires on memory performance and quality of life – important indicators of whether the drug might be helpful.

The trial will assess rate of whole brain shrinkage on MRI scan compared between participants on losartan and those on placebo. The researchers will also examine differences in brain blood flow, memory tests, day-to-day quality of life and changes in blood protein levels.

Professor Pat Kehoe, Gestetner Professor of Translational Dementia Research at the University of Bristol, leading the trial gave an update on the study on Friday [14 July] at a symposium on Vascular Factors in Dementia and Neurodegeneration in London, hosted by the International Society of Vascular, Behavioural and Cognitive Disorders (Vas-Cog Society).

Professor Kehoe said: "With an ageing population, and as we are still in search of longer acting and effective treatments, the provision for Alzheimer's disease care will continue to increase, which will greatly impact on NHS healthcare costs and resources.

"We are delighted with the confidence our funders have placed on us by agreeing to extend the study as it gives patients and their carers the opportunity to take part and help realise the potential of this UK-based trial. The scientific case is there but we now really need people with Alzheimer's disease to come forward and offer to take part as their involvement is essential to helping scientists find out if losartan could be a future treatment for Alzheimer's disease.

"What a lot people may not realise, even if they are seeing a doctor regularly to have their Alzheimer's treated, because of rules around data protection and privacy unless they voice their interest to take part in research, doctors, nurses and researchers working on various trials like RADAR are not always able to contact them to invite them to take part and so many people may miss out on opportunities to participate in research that may find new treatments."

Sandra, a carer for her husband Martin who are participants of the RADAR study, said: "It was a real shock when Martin was diagnosed with Alzheimer's disease and it has taken some time to come to terms with the diagnosis and disease.

"Even though we know the study can't help Martin, being part of the trial is important as it could help future generations. I hope that it's not long before a drug can be found to treat or keep Alzheimer’s disease at bay and research is important to make that happen."

If members of the public are interested in participating in the study, they can find the location and contact details of all of RADAR's participating NHS sites on www.radar-trial.org.uk. Further information about the study can also be found here as well as a chance to contact the study team. People can also lend their encouragement and follow the progress of the trial on Twitter @RADARTrialAD.

Members of the public interested in other research opportunities in relation to Alzheimer’s disease or other forms of dementia can also register with the new Join Dementia Research initiative, hosted by the National Institute of Health Research (NIHR).

The Join Dementia Research service allows anyone with and without dementia to sign up using basic demographic and health information and be matched to dementia research studies in their area. Research teams can then approach potential volunteers about their particular study and the volunteer can decide whether to take part on a case-by-case basis.