Understanding how blood thinners can prevent micro-strokes: the DARE2THINK Neurovascular sub study

Status: Ongoing

Atrial fibrillation (AF) is a common heart rhythm condition that leads to a high chance of stroke, frequent hospital admissions and poor quality of life. Patients also have a much higher risk of cognitive decline (trouble remembering, concentrating or making every-day decisions) and dementia. This may be due to silent ‘micro-strokes’ that gradually damage the brain over time. Blood thinning tablets are used for NHS patients with AF to lower the risk of stroke, but are usually only given to older patients or those with other health issues. This may be too late to avoid dementia.

DaRe2THINK is a new way of running trials that will use the health data already collected within the NHS for research that benefits the care of patients.  Based at GP surgeries across England, this trial will include patients that don’t normally take part in clinical trials, and follow them up without the need for additional visits. The trial, funded by the UK Department of Health, will include 3000 younger patients with AF. On a random basis, each patient will either continue their current treatment, or start a newer type of blood thinning tablet (a direct oral anticoagulant).

Project aims

Whilst the main trial will show whether these blood thinning tablets work to prevent strokes and blood clots, we still need to understand how they work, which patients benefit the most, and why some patients with AF develop dementia. This study within the main trial will help us to understand if these drugs work by preventing damage to the brain, whether they protect the structure of the brain (and so preserve brain function), or if they impact on blood vessels throughout the body.

160 patients who are already taking part in DaRe2THINK will be asked to undergo additional tests within a few months of joining the main trial. Half of the patients will be receiving blood thinners, and half from those on their normal medications. The tests include a brain magnet scan which is painless with no x-rays, reaction times and memory tests on a handheld computer, and eye tests. By looking at the blood vessels in the eye with a special camera, we can see what is happening to blood vessels everywhere. In total, these tests will take about 2 hours and will be repeated only once after 3 years. 

The design of the study has been advised by a Patient and Public Involvement team. Including this study within an existing trial means we can take advantage of the random assignment to blood thinners.

This study will target an issue of huge importance to patients, our NHS and the social care system. Understanding how blood thinners can prevent these micro-strokes could help doctors to personalise the management of patients, not only with AF, but also similar conditions that affect the blood vessels around the body. Preventing cognitive decline and dementia is a major public health priority for the NHS.