Susceptibility-Weighted Magnetic Resonance Imaging Highlights Brain Alterations in COVID Recovered Patients. (preprint)

The increasing number of reports of mild to severe psychological, behavioral, and cognitive sequelae in COVID-19 survivors motivates a need for a thorough assessment of the neurological effects of the disease. In this regard, we have conducted a neuroimaging study to understand the neurotropic behavior of the coronavirus. We hypothesize that the COVID-recovered subjects have developed alterations in the brain which can be measured through susceptibility differences in various regions of the brain when compared to healthy controls (HCs). Hence, we performed our investigations on susceptibility-weighted imaging (SWI) volumes. Fatigue, being of the most common symptoms of Long COVID, has also been studied in this work. SWI volumes of 46 COVID and 30 HCs were included in this study. The COVID patients were imaged within six months of their recovery. We performed an unpaired two-sample t-test over the pre-processed SWI volumes of both groups and multiple linear regression was performed to observe group differences and correlation of fatigue with SWI values. The group analysis showed that COVID recovered subjects had significantly higher susceptibility imaging values in regions of the frontal lobe and the brain stem. The clusters obtained in the frontal lobe primarily show differences in the white matter regions. The COVID group also demonstrated significantly higher fatigue levels than the HC group. The regression analysis on the COVID group yielded clusters in the anterior cingulate gyrus and midbrain, which exhibited negative correlations with fatigue scores. This study suggests an association of Long COVID with prolonged effects on the brain and also indicates the viability of the SWI modality for analysis of post-COVID symptoms.

Assessing functional connectivity differences and work-related fatigue in surviving COVID-negative patients. (preprint)

The recent Coronavirus Disease 2019 (COVID-19) has affected all aspects of life around the world. Neuroimaging evidence suggests the novel coronavirus can attack the central nervous system (CNS), causing cerebro-vascular abnormalities in the brain. This can lead to focal changes in cerebral blood flow and metabolic oxygen consumption rate in the brain. However, the extent and spatial locations of brain alterations in COVID-19 survivors are largely unknown. In this study, we have assessed brain functional connectivity (FC) using resting-state functional MRI (RS-fMRI) in 38 (25 males) COVID patients two weeks after hospital discharge, when PCR negative and 31 (24 males) healthy subjects. FC was estimated using independent component analysis (ICA) and dual regression. The COVID group demonstrated significantly enhanced FC in regions from the Occipital and Parietal Lobes, comparing to the HC group. On the other hand, the COVID group exhibited significantly reduced FC in several vermal layers of the cerebellum. More importantly, we noticed negative correlation of FC with self-reported fatigue within regions from the Parietal lobe, which are known to be associated with fatigue. Keywords: COVID, Functional Connectivity, ICA, Fatigue, RS-fMRI

Higher Limbic and Basal Ganglia volumes in surviving COVID-negative patients and the relations to fatigue. (preprint)

BackgroundAmong systemic abnormalities caused by the novel coronavirus, little is known about the critical attack on the central nervous system (CNS). Few studies have shown cerebrovascular pathologies that indicate CNS involvement in acute patients. However, replication studies are necessary to verify if these effects persist in COVID-19 survivors more conclusively. Furthermore, recent studies indicate fatigue is highly prevalent among long-COVID patients. How morphometry in each group relate to work-related fatigue need to be investigated. MethodCOVID survivors were MRI scanned two weeks after hospital discharge. We hypothesized, these survivors will demonstrate altered gray matter volume (GMV) and experience higher fatigue levels when compared to healthy controls, leading to stronger correlation of GMV with fatigue. Voxel-based morphometry was performed on T1-weighted MRI images between 46 survivors and 30 controls. Unpaired two-sample t-test and multiple linear regression were performed to observe group differences and correlation of fatigue with GMV. ResultsThe COVID group experienced significantly higher fatigue levels and GMV of this group was significantly higher within the Limbic System and Basal Ganglia when compared to healthy controls. Moreover, while a significant positive correlation was observed across the whole group between GMV and self-reported fatigue, COVID subjects showed stronger effects within the Posterior Cingulate, Precuneus and Superior Parietal Lobule. ConclusionBrain regions with GMV alterations in our analysis align with both single case acute patient reports and current group level neuroimaging findings. We also newly report a stronger positive correlation of GMV with fatigue among COVID survivors within brain regions associated with fatigue, indicating a link between structural abnormality and brain function in this cohort.