Blood Clues to Long-COVID Brain Fog Discovered

Summary: Researchers have discovered two blood biomarkers that could predict cognitive deficits, including “brain fog,” up to a year after a COVID-19 diagnosis. The study analyzed data from over 1,800 hospitalized patients and identified high levels of fibrinogen and d-dimer, proteins linked to blood coagulation, as being highly correlated with cognitive issues.

These findings were validated in an independent dataset comprising nearly 18,000 U.S. patients. The study offers a promising direction for managing the long-term cognitive effects of COVID-19.

Key Facts:

1. The study analyzed data from 1,837 U.K. patients hospitalized for COVID-19 and found two blood biomarkers—fibrinogen and d-dimer—linked to cognitive deficits.
2. A separate U.S. study involving 17,911 patients corroborated these findings, suggesting the specificity of d-dimer for COVID-19 cognitive issues.
3. The researchers propose that these biomarkers may help in developing models to predict, diagnose, and manage post-COVID-19 cognitive deficits, although more research is needed.

Source: Nature

Two blood biomarkers could be predictive of cognitive deficits six and 12 months after a diagnosis of COVID-19, reports a new study published in Nature Medicine.

These findings, based on data from more than 1,800 patients who were admitted to the hospital with COVID-19, were validated in an independent dataset, and provide biological insights into factors that may drive long-term cognitive dysfunction due to COVID-19.

Post-COVID-19 cognitive deficits, including “brain fog,” can be debilitating and affect day-to-day life. Their diagnosis includes both objective (clinician-based) components and subjective (patient-reported) components. However, how these post-COVID-19 cognitive deficits develop remains unknown.

Maxime Taquet and colleagues examined data collected from 1,837 patients hospitalized for COVID-19 in the U.K. between 29 January 2020 and 20 November 2021.

Blood samples were collected from these patents during admission to the hospital, and both clinician-acquired measurements and patient-reported measurements of cognition were obtained six and 12 months later.

Using a statistical approach, the authors identified two blood biomarker profiles that were highly correlated with post-acute COVID-19 cognitive deficits. The first profile identified high levels of fibrinogen, a protein associated with blood coagulation, that correlated with both objective cognitive deficits and subjective cognitive deficits.

The second profile associated elevated levels of another blood-coagulation protein, d-dimer, with subjective cognitive deficits, including “brain fog,” but also with fatigue and shortness of breath.

The findings were largely replicated in a separate study of the health records of 17,911 patients in the U.S., including comparison of post-pandemic cohorts versus pre-pandemic cohorts, which the authors suggest demonstrates the specificity of d-dimer for COVID-19.

The authors suggest that their findings may enable the development of models for post-COVID-19 cognitive deficits that could facilitate prognosis and management. However, they note that further research is needed in more cohorts.

About this Long-COVID research news

Author: Press Office
Source: Nature
Contact: Press Office – Nature
Image: The image is credited to Neuroscience News

Original Research: Open access.
“Acute blood biomarker profiles predict cognitive deficits 6 and 12 months after COVID-19 hospitalization” by Maxime Taquet et al. Nature Medicine

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Abstract

Acute blood biomarker profiles predict cognitive deficits 6 and 12 months after COVID-19 hospitalization

Post-COVID cognitive deficits, including ‘brain fog’, are clinically complex, with both objective and subjective components. They are common and debilitating, and can affect the ability to work, yet their biological underpinnings remain unknown.

In this prospective cohort study of 1,837 adults hospitalized with COVID-19, we identified two distinct biomarker profiles measured during the acute admission, which predict cognitive outcomes 6 and 12 months after COVID-19.

A first profile links elevated fibrinogen relative to C-reactive protein with both objective and subjective cognitive deficits. A second profile links elevated D-dimer relative to C-reactive protein with subjective cognitive deficits and occupational impact. This second profile was mediated by fatigue and shortness of breath.

Neither profile was significantly mediated by depression or anxiety. Results were robust across secondary analyses. They were replicated, and their specificity to COVID-19 tested, in a large-scale electronic health records dataset.

These findings provide insights into the heterogeneous biology of post-COVID cognitive deficits.