Banca de DEFESA: DIOGENES DIEGO DE CARVALHO BISPO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : DIOGENES DIEGO DE CARVALHO BISPO
DATE: 13/12/2023
TIME: 14:30
LOCAL: Plataforma TEAMS
TITLE:

COGNITIVE, OLFACTORY AND BRAIN MICROSTRUCTURAL ASSESSMENT AFTER COVID-19

KEY WORDS:

COVID-19, Brain, Fatigue, Cognition, Olfaction, Magnetic Resonance Imaging,
Neuronal Plasticity.

PAGES: 113
BIG AREA: Ciências da Saúde
AREA: Medicina
SUMMARY:

Background. Fatigue, cognitive complaints, and olfactory disfunction are the most frequent

persistent symptoms in patients after severe acute respiratory syndrome coronavirus 2 (SARS-
CoV-2) infection. This study aimed to assess fatigue and neuropsychological performance and

investigate changes in the thickness and volume of gray matter and microstructural
abnormalities in the white matter in a group of patients with mild-to-moderate coronavirus
disease 2019 (COVID-19). Additionally, we aimed to investigate changes in olfactory bulb
volume and brain network in the white matter in patients with persistent hyposmia following
COVID-19.
Methods. We studied 56 COVID-19 patients and 37 matched controls using magnetic
resonance imaging (MRI). Cognition was assessed using Montreal Cognitive Assessment and
Cambridge Neuropsychological Test Automated Battery, and fatigue was assessed using
Chalder Fatigue Scale (CFQ-11). The Sniffin' Sticks smell identification test (SS-16) was used
to evaluate participants' ability to identify odors. T1-weighted MRI was used to assess gray
matter thickness and volume. The olfactory bulbs were manually segmented from T2-weighted
MRI. Fiber-specific apparent fiber density (FD), free water index, and diffusion tensor imaging
data were extracted using diffusion-weighted MRI (d-MRI). Network-Based Statistics (NBS)
and graph theoretical analysis were used to explore the WM. d-MRI data were correlated with
clinical, cognitive measures, and SS-16 score using partial correlations and general linear
modeling.
Results. COVID-19 patients had mild-to-moderate acute illness (95% non-hospitalized). The
average period between real-time quantitative reverse transcription polymerase chain

reaction-based diagnosis and clinical/MRI assessments was 93.3 (±26.4) days. The COVID-
19 group had higher total CFQ-11 scores than the control group (p < 0.001). There were no

differences in neuropsychological performance between groups. The COVID-19 group had
lower FD in the association, projection, and commissural tracts, but no change in gray matter.
The corona radiata, corticospinal tract, corpus callosum, arcuate fasciculus, cingulate, fornix,
inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, superior longitudinal
fasciculus, and uncinate fasciculus were involved. CFQ-11 scores, performance in reaction

time, and visual memory tests correlated with microstructural changes in patients with COVID-
19.

The COVID-19 persistent hyposmia group had reduced olfactory bulb volume compared to
controls. In NBS, COVID-19 patients showed increased structural connectivity in a subnetwork
comprising parietal brain regions. Regarding global network topological properties, patients
exhibited lower global and local efficiency and higher assortativity than controls. Concerning
local network topological properties, patients had reduced local efficiency (left lateral orbital
gyrus and pallidum), increased clustering (left lateral orbital gyrus), increased nodal strength
(right anterior orbital gyrus), and reduced nodal strength (left amygdala). SS-16 test score was
negatively correlated with clustering of whole-brain white matter in the COVID-19 group.
Conclusions. Quantitative d-MRI detected changes in the white matter microstructure of
patients recovering from COVID-19. This study suggests a possible brain substrate underlying
the symptoms caused by SARS-CoV-2 during medium- to long-term recovery. Additionally,
patients with olfactory disfunction after COVID-19 had relevant white matter network
dysfunction with increased connectivity in the parietal sensory cortex. Reduced integration and
increased segregation are observed within olfactory-related brain areas might be due to
compensatory plasticity mechanisms devoted to recovering olfactory function.

COMMITTEE MEMBERS:
Externo à Instituição - BERNARDO CORRÊA DE ALMEIDA TEIXEIRA - UFPR
Interna - 2292514 - IRUENA MORAES KESSLER
Externa ao Programa - 1122557 - MARIA CLOTILDE HENRIQUES TAVARES - nullExterno à Instituição - NASSER ALLAM - NA
Presidente - 1550653 - NEYSA APARECIDA TINOCO REGATTIERI