Plain English Summary

Disease of the small blood vessels in the brain is an important cause of stroke and is the most common cause of cognitive impairment and dementia. High blood pressure is the major factor causing small vessel disease of the brain. We know that we greatly reduce the chance of this disease if we treat blood pressure (BP) before the disease develops. However, once people have established disease we do not know how intensively we should treat BP. Some doctors believe that even at this stage treating BP will reduce progression of the disease. Others believe that by the time well established disease develops, the brain is unable to cope with any reduction in blood flow caused by BP, and therefore, treating BP too intensively could worsen the disease and in particular, worsen cognition. The only way we can answer this question is by carrying out a clinical trial in a sufficiently large number of individuals. In this study Professor Hugh Markus and colleagues are testing the theory that by treating BP more intensively progression of the disease is delayed. They will also use state-of-the-art MRI imaging techniques to look at the mechanisms by which any beneficial effect of BP might occur. MRI techniques will allow the team to look at damage to the brain in a more sensitive way, and also at blood flow in the brain.