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expert reaction to study of blood biomarkers during hospitalisation with COVID and cognitive dysfunction at 6 and 12 months later

A study published in Nature Medicine looks at acute blood biomarker profiles and cognitive deficits 6 and 12 months after COVID-19 hospitalisation.

This Roundup accompanied an SMC Briefing.


Dr Aravinthan Varatharaj, NIHR Clinical Lecturer in Neurology, University of Southampton, said:

“This study reports that brain fog in long covid is associated with abnormal markers of blood clotting. These are robust and plausible findings backed by solid data from two independent sources.

“This is important because future research should look at whether treatment targeting blood clotting, for example blood thinners, might help people with these symptoms. Blood thinners are already routinely given to most people in hospital with covid. We do not know whether they are beneficial for symptoms after covid.

“However, several large studies have shown that stronger blood thinning treatment during acute covid has little or no benefit and is potentially harmful due to increased risk of bleeding. Further studies should look at whether certain people might benefit from targeted blood thinning treatment during and after covid.

“The study looked at self-reported (subjective) thinking problems as well as those found on formal (objective) testing; this is important because though brain fog is common and disabling it does not have an accepted medical definition and probably describes more than one set of related symptoms. It is interesting that raised fibrinogen, which might have a direct effect on the brain, was associated with both objective and subjective thinking problems, suggesting a common mechanism. Whereas raised D-dimer, which is linked to lung problems, was only associated with subjective thinking problems, suggesting perhaps effects of low oxygen levels and fatigue.”



‘Acute blood biomarker profiles predict cognitive deficits 6 and 12 months after COVID-19 hospitalization’ by Maxime Taquet et al. was published in Nature Medicine at 16:00 UK time on Thursday 31 August.




Declared interests

Dr Aravinthan Varatharaj: I have been involved in nationwide surveillance for neurological complications of COVID. I have provided medical advice to the charity Headway on COVID and the brain.

For all other experts, no reply to our request for DOIs was received.

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