A potential approach to treating small vessel disease, one of the commonest causes of dementia and stroke in older people, has been uncovered by a team of scientists led by the University of Edinburgh. Studies with rats found the treatment can reverse changes in blood vessels in the brain associated with the condition.
Treatment also prevents damage to brain cells caused by these blood vessel changes, raising hope that it could offer a therapy for dementia.
Small vessel disease, or SVD, is a major cause of dementia and can also worsen the symptoms of Alzheimer’s disease. It is responsible for almost half of all dementia cases in the UK and is a major cause of stroke, accounting for around one in five cases.
Small Vessel Disease
Patients with small vessel disease are diagnosed from brain scans, which detect damage to white matter — a key component of the brain’s wiring. Until now, it was not known how changes in small blood vessels in the brain associated with SVD can cause damage to brain cells.
The researchers found that SVD occurs when cells that line the small blood vessels in the brain become dysfunctional. This causes them to secrete a molecule into the brain.
The molecule stops production of the protective layer that surrounds brain cells — called myelin — which leads to brain damage. Treating rats with drugs that stop blood vessel cells from becoming dysfunctional reversed the symptoms of SVD and prevented brain damage, tests found.
Researchers say that further studies will need to test whether the treatment also works when the disease is firmly established. They will also need to check if the treatment can reverse the symptoms of dementia.
The research was carried out at the Medical Research Council Centre for Regenerative Medicine and the UK Dementia Research Institute at the University of Edinburgh. It was funded by the MRC, Alzheimer’s Research UK and Fondation Leducq.
“This important research helps us understand why small vessel disease happens, providing a direct link between small blood vessels and changes in the brain that are linked to dementia. It also shows that these changes may be reversible, which paves the way for potential treatments,"
Professor Anna Williams, Group Leader at the University of Edinburgh’s MRC Centre for Regenerative Medicine, said.
“Changes to the blood supply in the brain play an important role in Alzheimer’s disease as well as being a direct cause of vascular dementia. This pioneering research highlights a molecular link between changes to small blood vessels in the brain and damage to the insulating ‘white matter’ that helps nerve cells to send signals around the brain.
The findings highlight a promising direction for research into treatments that could limit the damaging effects of blood vessel changes and help keep nerve cells functioning for longer. There are currently no drugs that slow down or stop Alzheimer’s disease and no treatments to help people living with vascular dementia. Alzheimer’s Research UK is very pleased to have helped fund this innovative research, which is only possible thanks to the work of our dedicated supporters,"
Dr. Sara Imarisio, Head of Research at Alzheimer’s Research UK said.
Dementia is one of the biggest problems facing society, as people live longer and the population ages. Estimates indicate there are almost 47 million people living with dementia worldwide and the numbers affected are expected to double every 20 years, rising to more than 115 million by 2050.
Rikesh M. Rajani, Sophie Quick, Silvie R. Ruigrok, Delyth Graham, Sarah E. Harris, Benjamin F. J. Verhaaren, Myriam Fornage, Sudha Seshadri, Santosh S. Atanur, Anna F. Dominiczak, Colin Smith, Joanna M. Wardlaw, Anna Williams Reversal of endothelial dysfunction reduces white matter vulnerability in cerebral small vessel disease in rats Science Translational Medicine 04 Jul 2018: Vol. 10, Issue 448, eaam9507 DOI: 10.1126/scitranslmed.aam9507
Image: R.M. Rajani et al., Science Translational Medicine