Cortical Grey matter volume depletion links to neurological sequelae in post COVID-19 “long haulers” 2023, Rothstein

Abstract
Objective

COVID-19 (SARS-CoV-2) has been associated with neurological sequelae even in those patients with mild respiratory symptoms. Patients experiencing cognitive symptoms such as “brain fog” and other neurologic sequelae for 8 or more weeks define “long haulers”. There is limited information regarding damage to grey matter (GM) structures occurring in COVID-19 “long haulers”. Advanced imaging techniques can quantify brain volume depletions related to COVID-19 infection which is important as conventional Brain MRI often fails to identify disease correlates. 3-dimensional voxel-based morphometry (3D VBM) analyzes, segments and quantifies key brain volumes allowing comparisons between COVID-19 “long haulers” and normative data drawn from healthy controls, with values based on percentages of intracranial volume.

Methods
This is a retrospective single center study which analyzed 24 consecutive COVID-19 infected patients with long term neurologic symptoms. Each patient underwent Brain MRI with 3D VBM at median time of 85 days following laboratory confirmation. All patients had relatively mild respiratory symptoms not requiring oxygen supplementation, hospitalization, or assisted ventilation. 3D VBM was obtained for whole brain and forebrain parenchyma, cortical grey matter (CGM), hippocampus, and thalamus.

Results
The results demonstrate a statistically significant depletion of CGM volume in 24 COVID-19 infected patients. Reduced CGM volume likely influences their long term neurological sequelae and may impair post COVID-19 patient’s quality of life and productivity.

Conclusion
This study contributes to understanding effects of COVID-19 infection on patient’s neurocognitive and neurological function, with potential for producing serious long term personal and economic consequences, and ongoing challenges to public health systems.

https://bmcneurol.biomedcentral.com/articles/10.1186/s12883-023-03049-1

 

It's at least possible that people with less grey matter than average are more likely to develop long-covid, or at least report more severe symptoms. I wonder how PWME would compare, and whether the length or severity of ME would affect the volume of grey matter.

 

See also —

Gray Matter Changes Following Mild COVID-19: An MR Morphometric Study in Healthy Young People (2023, Journal of Magnetic Resonance Imaging)

Background: Although COVID-19 is primarily an acute respiratory infection, 5%–40% of patients develop late and prolonged symptoms with frequent neurological complaints, known as long COVID syndrome. The presentation of the disease suggests that COVID infection may cause functional and/or morphological central nervous system alterations, but studies published in the literature report contradictory findings.

Purpose: To investigate the chronic effects of COVID-19 on cerebral grey matter in a group of young patients without comorbidities, with mild course of COVID infection and no medical complaints at the time of examination.

Study Type: Prospective.

Population: Thirty-eight young (age = 26.6 ± 5.0 years; male/female = 14/24), adult participants who recovered from mild COVID infection without a history of clinical long COVID and 37 healthy control subjects (age = 25.9 ± 2.8 years; male/female = 14/23).

Field Strength/Sequence: Three Tesla, 3D T1-weighted magnetization-prepared rapid gradient-echo, 2D T2-weighted turbo spin-echo.

Assessment: MRI-based morphometry and volumetry along with neuropsychological testing and self-assessed questionnaire.

Statistical Tests: Fisher’s exact test, Mann–Whitney U-test, and multiple linear regression analyses were used to assess differences between COVID and healthy control groups. P < 0.05 was used as cutoff for significance.

Results: In the COVID group, significantly lower bilateral mean cortical thickness (left/right-hemisphere: 2.51 ± 0.06 mm vs. 2.56 ± 0.07 mm, η p 2 = 0.102/2.50 ± 0.06 mm vs. 2.54 ± 0.07 mm, η p 2 = 0.101), lower subcortical gray matter (57881 ± 3998 mm 3 vs. 60470 ± 5211 mm3 , η p 2 = 0.100) and lower right olfactory bulb volume (52.28 ± 13.55 mm3 vs. 60.98 ± 15.8 mm3 , η p 2 = 0.078) were found. In patients with moderate to severe anosmia, cortical thickness was significantly lower bilaterally, as compared to patients without olfactory function loss (left/right-hemisphere: 2.50 ± 0.06 mm vs. 2.56 ± 0.05 mm, η 2 = 0.173/2.49 ± 0.06 mm vs. 2.55 ± 0.05 mm, η 2 = 0.189). Using further exploratory analysis, significantly reduced cortical thickness was detected locally in the right lateral orbitofrontal cortex in the COVID group (2.53 ± 0.10 mm vs. 2.60 ± 0.09 mm, η p 2 = 0.112).

Data Conclusion: Even without any subjective or objective neurological complaints at the time of the MR scan, subjects in the COVID group showed gray matter alterations in cortical thickness and subcortical gray matter volume.

Level of Evidence: 2 Technical Efficacy: Stage 3