COVID-19 induces grey matter atrophy in patients with cognitive but also with only olfactory disorders
Author Block: S. Capelli1, A. Caroli1, A. Arrigoni1, A. Napolitano2, G. Pezzetti2, A. Remuzzi3, F. L. Lorini2, M. Sessa2, S. Gerevini2; 1Ranica/IT, 2Bergamo/IT, 3Dalmine/IT
Purpose: The aim of this study was to evaluate grey matter (GM) structural alterations related to COVID-19 in two separate groups of patients with the most frequent and distinctive COVID-19-related neurological manifestations - isolated olfactory disorders (COVID-OD) and cognitive disorders (COVID-CM) – compared to a control group of healthy individuals.
Methods or Background: Sixty-one COVID-CM patients (57[60–63] years, 62% females), 84 COVID-OD patients (49[35–57] years, 60% females) and 17 controls (51[41–52] years, 41% females) were included in the study. To investigate differences between patients and controls in terms of GM regional volume and voxel-wise density, Region-Based Morphometry (RBM) and Voxel-Based Morphometry (VBM) were applied to T1-weighted MRI scans. Surface-Based Morphometry (SBM) was used to investigate changes in cortical thickness.
Total intracranial volume and age were included as nuisance variables in the statistical model assessing group differences.
Results or Findings: The multi-morphometric analysis revealed statistically significant reduction in GM regional volume (RBM) and density (VBM) as well as lower cortical thickness in both COVID-CM and COVID-OD groups compared to controls. Notably, COVID-CM patients showed more widespread and severe tissue loss than COVID-OD patients.
The most affected GM regions were hippocampus, putamen, cingulate cortex, praecuneus, amygdala, lingual gyrus, and caudate nucleus. Most of the atrophic regions are known to be involved in memory processes, in the sense of smell, or both.
Conclusion: Current MRI findings indicate that, with varying degrees of severity, both COVID-19-related olfactory and cognitive disorders lead to GM atrophy, possibly reflecting neurodegeneration and neuroinflammation. The COVID-CM group showed more pronounced GM changes, suggesting a stronger inflammatory response.
Limitations: This was a retrospective and monocentric study, with a small control population. Quantitative clinical data assessing the severity of olfactory or cognitive disorders was not available.
Funding for this study: This study received partial support from Brembo SpA (Curno, Bergamo, Italy) through the "Progetto TrexUno" initiative.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The use of patient data was granted ethical approval by the local ethics committee as part of a broader observational study protocol (Reg. 118/22). Informed consent was acquired from patients or from their next of kin (in the case of ICU patients).