Researchers at The University of Manchester have found that tracking changes in a protein linked to inflammation (interleukin-6) after a stroke could help identify people at risk of later memory and thinking problems (also known as cognitive problems). The study also suggests that smoking may make people more at risk of memory and thinking problems in association with ongoing inflammation after a stroke.
The research, published in Alzheimer's & Dementia, is part of the Stroke IMPaCT study (Stroke - Immune Mediated Pathways and Cognitive Trajectory), a network of European and North American researchers who are working to discover how inflammation and immune responses contribute to post-stroke cognitive decline.
The team followed patients treated for an ischaemic stroke at Salford Royal Hospital, part of Northern Care Alliance NHS Foundation Trust. They measured levels of a protein called interleukin-6 (IL-6) in the days after stroke and again at both 6-9 and 18-21months. Participants also completed detailed tests of memory and thinking.
Interleukin-6 levels increased soon after stroke and, in most people, fell back to typical levels within 6-9 months. But in some patients, levels stayed high or rose again. These individuals were about eight times more likely to develop difficulties with thinking ability.
The researchers also saw differences between smokers and non-smokers. Smokers showed a different pattern of IL-6 change after stroke, with signs of longer-lasting inflammation. This ongoing inflammation was more strongly linked to problems with thinking and memory.
Lead author Natasha Carmichael, an MBPhD researcher at The University of Manchester, said: "Inflammation after stroke doesn't just happen once and disappear. By tracking this protein over time, we may be able to identify patients at greater risk of cognitive problems and eventually tailor support or treatments to them."
Professor Craig Smith, Professor of Stroke Medicine at The University of Manchester and Consultant at Salford Royal, said: "Our findings suggest it's not just the initial spike in inflammation that matters- it's whether it properly settles down after the stroke. Smoking appears to interfere with this recovery, leaving people more vulnerable to memory and thinking problems.
Professor Stuart Allan added: "When the immune system's recovery after stroke doesn't occur as expected, patients appear more likely to experience cognitive difficulties. If future studies confirm interleukin-6 is the cause, we might one day use medications that block it to protect brain health."
Co-lead author Harry Deijnen from the University of Manchester added: "Though it is clear that more research is needed, these results point towards new opportunities to improve long-term brain health by focusing on the body's inflammatory recovery after stroke."
