Scientists have uncovered a previously overlooked cause of one of the most common types of stroke, offering clues as to why some treatments don’t work.
Lacunar strokes, which account for a quarter of all strokes, affecting around 35,000 people in the UK every year, were previously thought to be triggered by a build-up of fatty deposits in the brain.
However, researchers at the University of Edinburgh say the life-threatening condition is, in fact, caused by the widening of arteries in the brain.
Experts say the findings may explain why common stroke treatments, like aspirin and other blood-thinning tablets, are often not effective for lacunar stroke patients.
Professor Joanna Wardlaw, an expert in brain imaging and heart disease, and study lead author said: ‘This study provides strong evidence that lacunar stroke is not caused by fatty blockage of larger arteries, but by disease of the small vessels within the brain itself.
‘Recognising this distinction is crucial, because it explains why conventional treatments like anti-platelet drugs are not as effective for this type of stroke and highlights the urgent need to develop new therapies that target the underlying microvascular damage.’
Stroke typically occurs when the blood supply to part of the brain is cut off – as a result of a blockage or bleeding in and around the brain.
Around 100,000 people have strokes every year in the UK, which is roughly one stroke every five minutes. The condition kills around 35,000 annually.
Strokes occurs when blood supply to the brain is cut off, either by a blood clot or a burst blood vessel
High blood pressure, smoking, high cholesterol, diabetes and obesity all raise the risk of strokes.
Preventative treatments typically involve drugs that prevent blood clots from forming, such as a daily aspirin tablet.
However, the exact cause of lacunar strokes has eluded experts for decades.
The new study – published in the medical journal Circulation – followed 229 patients who had suffered either lacunar or mild non-lacunar stroke.
Participants underwent a brain scan and other clinical tests, which measured their vitals and cognitive ability, immediately after their stroke.
A year later, the same tests were completed, allowing the researchers to track changes over time.
Crucially, they found the narrowing of arteries due to a build-up of fatty deposits – a common cause of stroke – was not linked to lacunar strokes.
In contrast, this type of stroke appeared to be linked with the widening of arteries.
Patients with this feature were more than four times more likely to have lacunar stroke.
Experts believe that this arterial widening is caused by a condition called small vessel disease, where blood vessels breakdown and degenerate.
It is this damage, rather than blood clots, that seems to trigger lacunar strokes.
The researchers concluded that future research should focus on treating underlying small vessel damage – rather than simply preventing blood clots.