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Updated: Sep 3, 2025
A Free-breathing fMRI Method to Study Human Olfactory Function
Published on: July 30, 2017
Mid-term MRI evaluation reveals microstructural white matter alterations in COVID-19 fully recovered subjects with
Laura Pelizzari1, Marta Cazzoli1, Susanna Lipari1
1IRCCS Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy.
Background:
Little is still known about the mid/long-term effects of coronavirus disease 2019 (COVID-19) on the brain, especially in subjects who have never been hospitalized due to the infection. In this neuroimaging exploratory study, we analyzed the medium-term effect of COVID-19 on the brain of people who recovered from COVID-19, experienced anosmia during the acute phase of the disease, and have never been hospitalized due to SARS-Co-V-2 infection.
Methods:
Forty-three individuals who had (COV+, n = 22) or had not (COV-, n = 21) been infected with SARS-Co-V-2 were included in the study; the two groups were age- and sex-matched and were investigated using 3T magnetic resonance imaging (MRI). Gray matter (GM) volume, white matter (WM) hyperintensity volume, WM microstrutural integrity (i.e. fractional anisotropy [FA], mean diffusivity [MD], axial diffusivity [AD], radial diffusivity [RD]) and cerebral blood flow (CBF) differences between the two groups were tested with either analysis of covariance or voxel-wise analyses. Results were family wise error (FWE) corrected.
Results:
No significant differences between COV+ and COV- groups were observed in terms of GM volume, WM hyperintensity volume, and CBF. Conversely, local WM microstructural alterations were detected in COV+ when compared with COV- with tract-based spatial statistics. Specifically, COV+ showed lower FA (pFWE-peak = 0.035) and higher RD (pFWE-peak = 0.038) than COV- in several WM regions.
Conclusion:
COVID-19 may produce mid/long-term microstructural effect on the brain, even in case of mild-to-moderate disease not requiring hospitalization. Further investigation and additional follow-ups are warranted to assess if the alterations reported in this study totally recover over time. As brain alterations could increase the risk of cognitive decline, greater knowledge of their trajectories is crucial to aid neurorehabilitation treatments.
Insights
Mild COVID-19 can cause long-term brain microstructural changes, even without hospitalization. These alterations in white matter integrity may impact cognitive function, highlighting the need for further research and neurorehabilitation strategies.
Area of Science:
- Neuroscience
- Radiology
- Infectious Diseases
Background:
- The long-term neurological effects of coronavirus disease 2019 (COVID-19) remain largely unknown, particularly in individuals with mild infections not requiring hospitalization.
- This study focuses on individuals who recovered from COVID-19, experienced anosmia, and were never hospitalized due to SARS-CoV-2 infection.
Purpose of the Study:
- To investigate the medium-term effects of COVID-19 on the brain in non-hospitalized individuals.
- To analyze differences in brain structure and white matter integrity between individuals who had COVID-19 and a control group.
Main Methods:
- Utilized 3T magnetic resonance imaging (MRI) to compare 43 individuals (22 COVID-19 positive, 21 controls), matched for age and sex.
- Assessed gray matter (GM) volume, white matter (WM) hyperintensity volume, WM microstructural integrity (FA, MD, AD, RD), and cerebral blood flow (CBF).
- Employed analysis of covariance and voxel-wise analyses with family-wise error (FWE) correction.
Main Results:
- No significant differences were found in GM volume, WM hyperintensity volume, or CBF between the COVID-19 positive (COV+) and control (COV-) groups.
- Tract-based spatial statistics revealed significant local WM microstructural alterations in the COV+ group compared to the COV- group.
- Specifically, the COV+ group exhibited lower fractional anisotropy (FA) and higher radial diffusivity (RD) in several WM regions.
Conclusions:
- COVID-19 may induce mid/long-term microstructural brain effects, even in mild cases not requiring hospitalization.
- Further research and follow-up studies are necessary to determine if these WM alterations are reversible.
- Understanding the trajectory of these brain changes is crucial for developing effective neurorehabilitation treatments and mitigating potential cognitive decline.
