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The University of Exeter Medical School led the study which analysed data on stroke and dementia risk from 3.2 million people across the world. The link between stroke and dementia persisted even after taking into account other dementia risk factors such as blood pressure, diabetes and cardiovascular disease.
The study builds on previous research which had established the link between stroke and dementia, though had not quantified the degree to which stroke actually increased dementia risk. To better understand the link between the two, researchers analysed 36 studies where participants had a history of stroke, totalling data from 1.9 million people.
In addition, they analysed a further 12 studies that looked at whether participants had a recent stroke over the study period, adding a further 1.3 million people. They discovered that a history of stroke increases dementia risk by 70%, and recent strokes more than doubled the risk. Improvements in stroke prevention and post-stroke care may play a key role in dementia prevention.
According to the World Health Organisation, 15 million people have a stroke each year. Meanwhile, around 50 million people globally have dementia. Stroke characteristics such as the location and extent of brain damage may help to explain variation in dementia risk observed between studies, and there was some suggestion that dementia risk may be higher for men following stroke.