A Possible Biomarker for COVID-19 Cognitive Impairment

The study covered in this summary was published on medRxiv.org as a preprint and has not yet been peer reviewed.

Key Takeaways

  • This study demonstrated that participants with previous SARS-CoV-2 infections had mild to moderate cognitive impairment up to 4 months after diagnosis, independently of baseline cognitive function.

  • Mild cognitive decline is associated with kynurenine pathway (KP) activation, suggesting KP metabolites are a potential biomarker and therapeutic target.

Why This Matters

Study Design

  • The study enrolled 128 unvaccinated participants with nasopharyngeal swab-confirmed SARS-CoV-2 infection through the Sydney St. Vincent’s Hospital COVID-19 ADAPT prospective study.

    • The average age of the participants was 46.6 years (range, 20 – 79 years).

    • 42% of participants were women.

  • Cognitive and olfactive function along with blood cytokine level, neurobiomarkers, and KP metabolites were assessed 2, 4, and 12 months after confirmed diagnosis.

  • Lung function, physical health, and mental health were assessed 2 months post diagnosis.

    • Participants were divided into three acute severity groups that were based on acute COVID-19 illness history.

    • Key Results

      • Overall cognitive performance significantly declined (P < .001).

        • Cognitive impairment was more common among participants who reported anosmia 2 months post diagnosis (P = .05).

      • Mild to moderate cognitive impairment was observed in 16% of participants 2 months after diagnosis; in 23% 4 months after diagnosis; and in 26% 12 months after diagnosis.

      • Cognitive decline was significantly associated with KP metabolites, quinolinic acid, 3-hydroxyanthranilic acid, and kynurenine (P < .001).

      • Limitations

        • The overall sample size was small, as was the subsample of patients with severe cases.

        • The sample was restricted to higher socioeconomic populations of Sydney, and the findings may not be generalizable to all patient populations.


        • This study was funded by the St. Vincent’s Hospital ADAPT study at St. Vincent’s Centre for Applied Medical Research.

        • The published article contains a listing of authors’ relevant financial relationships.

        This is a summary of a preprint research study, “Post-acute COVID-19 Cognitive Impairment and Decline Uniquely Associate With Kynurenine Pathway Activation: A Longitudinal Observational Study,” written by Lucette A. Cysique from the St. Vincent’s Centre for Applied Medical Research in Australia and colleagues. It was published by medRxiv.org and is provided to you by Medscape. This study has not yet been peer reviewed. The full text of the study can be found on medRxiv.org.

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