Gene tests could one day be used to spot patients at risk of ‘silent’ strokes that cause dementia, scientists believe. Researchers studied genetic samples of thousands of people who’d suffered a lacunar stroke – caused by weakening of the blood vessels deep within the brain – and compared them to those who hadn’t. Twelve similarities were found in the stroke victims’ DNA. As the blood vessels affected by a lacunar stroke are small, it can strike without the person knowing. High blood pressure, type 2 diabetes and a history of smoking are causally associated with an increased risk of lacunar stroke.