Microstructural brain abnormalities, fatigue, and cognitive dysfunction after mild COVID-19

The study titled “Microstructural brain abnormalities, fatigue, and cognitive dysfunction after mild COVID-19” aimed to investigate cognitive dysfunction and brain changes in individuals who experienced mild SARS-CoV-2 infection. A total of 97 unvaccinated individuals, with a median age of 41 years, were examined approximately 79 days (median) after their COVID-19 diagnosis. The participants underwent semi-structured interviews, neurological examinations, 3T-MRI scans, and neuropsychological assessments. The study excluded individuals with current or a history of psychiatric symptoms, including anxiety and depression, to avoid biases related to brain changes and cognitive dysfunction associated with these conditions.

Key Findings:

  1. Symptoms Reported by Participants: The participants commonly reported memory loss (36%), fatigue (31%), and headache (29%). Quantitative analyses confirmed symptoms of fatigue (83%), excessive somnolence (35%), impaired phonemic verbal fluency (21%), impaired verbal categorical fluency (13%), and impaired logical memory immediate recall (16%).
  2. Neuroimaging Results:
    • White Matter (WM) Analyses: Diffusion tensor imaging (DTI) revealed higher axial diffusivity values in post-infected patients compared to controls. No significant differences were observed in the functional connectivity of the posterior cingulate cortex.
    • Functional Connectivity (FC) Analyses: The study focused on the default mode network (DMN) but did not identify significant differences in functional connectivity between patients and controls after applying False Discovery Rate (FDR) correction. The relationship between DMN maps and scores of fatigue and sleepiness was also investigated, with no significant results observed.
  3. Cognitive Dysfunction and COVID-19: The study confirmed post-infectious cognitive dysfunction in survivors of COVID-19. However, cognitive impairment after mild infection is not well understood. The participants presented higher rates of impairments in phonemic verbal fluency (20.8%), semantic verbal fluency (16.3%), episodic immediate verbal memory (16.3%), and processing speed.
  4. White Matter Alterations: Although some studies have demonstrated changes in white matter in hospitalized survivors, fewer have investigated alterations in individuals after a mild infection. The study found higher axial diffusivity values in post-COVID patients compared to controls but no significant correlations between neuroimaging features and neuropsychological scores.

Conclusions:

The study suggests that even mild SARS-CoV-2 infection can lead to persistent cognitive impairment and subtle white matter abnormalities. The absence of significant differences in the functional connectivity of the DMN and the lack of correlation between neuroimaging features and neuropsychological scores highlight the need for further research. The findings emphasize the importance of longitudinal follow-up of patients recovered from COVID-19, even in those mildly infected, to understand the long-term impact of the infection on cognitive function and brain structure. Specific treatment of symptoms and neurorehabilitation strategies may be necessary to improve the quality of life and cognitive function for those with persistent limitations after the acute phase​​.

Read More: https://www.nature.com/articles/s41598-024-52005-7

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