European Stroke Organisation Conference (ESOC)
May 16–18, 2017

May 16, 2017
It was refreshing to see a full hall at the ESOC session about the impact of stroke and cognition. In stroke research, it is easy to get distracted by exciting and dramatic things (such as thombectomy working for people who wake up with stroke) and forget some of the other things that are just as important to our patients. Fortunately, the relationship between stroke and cognitive impairment is now firmly on the research agenda.

We know that stroke increases the risk of dementia, but it’s difficult to say just HOW much. The existing data is quite confusing; if you look at patients who have had a large stroke, many will have cognitive impairment, but again many will be unable to take part in cognitive tests. The picture is quite different if we only look at patients with a mild stroke or TIA, as far fewer will have cognitive impairment. The problem is that many studies are only able to recruit patients with milder stroke. To make the problem worse, patients with severe stroke will not survive, so if you are not careful, it can seem that patients with milder stroke are more likely to have dementia at one year.

Fortunately, the OxVASC study is here to sort things out. Sarah Pendlebury presented some preliminary results. The useful thing about OxVASC is that it follows up all patients from a selected group of 9 general practices in Oxfordshire who have a stroke or TIA. Because nearly all patients are included and the follow-up is almost complete, there’s a much lower risk of what we call attrition bias (patients with more severe stroke not surviving).

Dr. Pendlebury demonstrated that there was a step-wise association between stroke severity and the likelihood of dementia. The more severe the stroke, the higher the chance of dementia. To make things more complicated, having dementia increases the chance of having a stroke. The biggest increase in risk of dementia is within one year of the stroke itself. When she looked at people who had two strokes, the size of both strokes was predictive of dementia: So if you have had one stroke, you are at increased risk of dementia if you have another one. She also found that education was protective against post-stroke dementia; however, being older increased the risk, as did being diabetic, having a recurrent stroke, and background small vessel disease.

This all comes together to point to the fact that preventative medicine, which reduces the risk of stroke, is likely to also reduce the risk of dementia. This is important to many of my older patients who are not interested in taking medication to prevent stroke, but may want to prevent dementia.

—Stephen Makin, PhD