A clinical trial is to find out whether cheap, readily available drugs can prevent dementia after stroke.
Two charities, the British Heart Foundation and Alzheimer's Society, are working together to test the approach.
Over three years, a team led by Professor Joanna Wardlaw at the University of Edinburgh will see what effect the drugs have on around 400 stroke patients.
The LACI-2 trial, to be launched during Dementia Awareness Week, focuses on lacunar stroke - a type of stroke that affects the smallest blood vessels in the brain.
Research suggests lacunar strokes could contribute to at least 40% of dementias, even when the main cause is Alzheimer's disease. Lacunar strokes affect around 35,000 people in the UK each year.
The drugs being tested are cilostazol, which costs about 63p per tablet and is used to treat peripheral arterial disease, and the angina pill isosorbide mononitrate, which is even cheaper at 7p.
Standard anti-clotting agents including aspirin may be harmful in cases of lacunar stroke.
Prof Wardlaw said: "I'm thrilled to see two charities working together to fund our research so that we can bring benefits to people who have had a lacunar stroke, and are at risk of developing cognitive decline, as soon as possible."
Dr Shannon Amoils, senior research adviser at the British Heart Foundation, said: "We know that lacunar strokes can cause brain damage, affecting the way people walk and think, so there is a strong link to dementia.
"With no treatments for lacunar stroke, this important trial will establish if two drugs, already available in the UK for other conditions, are safe to use in people with this type of stroke."
Dr Doug Brown, chief policy and research officer at Alzheimer's Society, said: "Finding an existing drug which can prevent dementia would be a huge breakthrough, so it's really promising to see from the trial we funded that two drugs with this potential were safe to use for people with stroke."