Researchers have pinpointed the potential cause of a type of stroke suffered by hundreds of thousands of people around the world every year, which could explain why widely-used treatments do not work.
The discovery could also help pave the way for new treatments for lacunar strokes, which are caused by damage to the tiny blood vessels deep within the brain.
They can lead to people developing problems with thinking, memory, movement, and ultimately, dementia.
Unlike ischaemic strokes, which are caused by a blocked blood vessel, experts at the University of Edinburgh and the UK Dementia Research Institute in Britain suggest lacunar strokes may be caused by the widening of arteries in the brain.
The study included 229 people who had experienced a lacunar or mild non-lacunar stroke.
They underwent cognitive tests and brain scans at the time of the stroke, and again one year later.
Researchers tracked the cause of the stroke, signs of small vessel disease and new areas of brain damage.
The analysis found that the narrowing of large arteries was not linked to lacunar stroke, but rather, the widening of arteries.
Patients with widened arteries were four times more likely to have a lacunar stroke, according to the study.
This could explain why usual treatments, such as anti-platelet drugs, which stop blood clots from forming in the arteries, do not work, researchers said.
Elsewhere, widened arteries were also linked to a higher risk of having so- called silent strokes, which happen without obvious symptoms.
More than one in four patients had silent strokes during the study, despite being on treatment to help prevent further strokes.
Health experts estimate that lacunar strokes account for about a fifth of all strokes.
Experts have called for new treatments to target the underlying damage to the small blood vessels in the brain.
University of Edinburgh’s Institute for Neuroscience and Cardiovascular Disease professor of applied neuroimaging and UK Dementia Research Institute group leader Dr Joanna Wardlaw 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.”
The findings, published in the journal Circulation, are being used in studies exploring lacunar stroke treatments, including the LACunar Intervention Trial 3 (LACI-3), which is testing if existing drugs are effective against the condition.
Reacting to the study, the British-based Stroke Association policy director Dr Maeva May said: “Stroke research is chronically underfunded, with less than 1% of total UK research funding spent on the condition.
“Yet, these findings illustrate the value of research and the potential it has to change the lives of stroke patients.
“This study – and more of its kind – need to be a national priority across the NHS [National Health Service], government and the wider research community with clear pathways to carry breakthrough discoveries from laboratory to patients.” – PA Media/dpa
