The development of blood clots during COVID-19 infection could be behind continued cognitive problems of some individuals, a new paper has suggested.
Dr Max Taquet and colleagues from the University of Oxford, UK, analysed blood tests from 1,837 people who had been hospitalised with COVID-19.
They found two potential biomarkers associated with subsequent cognitive problems, such as serious and persistent problems with thinking, concentration and memory.mThe first was a high level of fibrinogen and the second was a raised level of the protein fragment D-dimer.
Writing in Nature Medicine, the authors say other aspects of the profiles suggest they are likely to reflect blood clots.
Dr Taquet said: “Both fibrinogen and D-dimer are involved in blood clotting, and so the results support the hypothesis that blood clots are a cause of post-COVID cognitive problems.
“Fibrinogen may be directly acting on the brain and its blood vessels, whereas D-dimer often reflects blood clots in the lungs and the problems in the brain might be due to lack of oxygen. In line with this possibility, people who had high levels of D-dimer were not only at a higher risk of brain fog, but also at a higher risk of respiratory problems.”
The research participants are part of the UKRI funded PHOSP-COVID (Post-hospitalisation COVID-19) study, led by University of Leicester, and their memory was assessed at six and 12 months after hospitalisation using both a formal test and by asking them their own subjective view about their memory.
Acute blood biomarker profiles predict cognitive deficits 6 and 12 months after COVID-19 hospitalisation. Nature Medicine 31 August 2023.
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