Developing a test for long COVID ‘brain fog’

Replication and generalization of the findings using electronic health records data. Kaplan–Meier curves represent the cumulative incidence of cognitive deficits between those with high versus low fibrinogen (or D-dimer) and CRP level ≤10 mg l−1. The same analysis conducted in people without COVID-19 (bottom). Curves represent the Kaplan–Meier estimates and shading around curves represents 95% CI. P values are derived from log-rank tests, are two-sided and not adjusted for multiple comparisons. Credit: Nature Medicine (2023). DOI: 10.1038/s41591-023-02525-y

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.

More information:
Maxime Taquet et al, Acute blood biomarker profiles predict cognitive deficits 6 and 12 months after COVID-19 hospitalization, Nature Medicine (2023). DOI: 10.1038/s41591-023-02525-y

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Developing a test for long COVID ‘brain fog’ (2023, September 1)
retrieved 4 September 2023

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