Scientific Reports (Aug 2023)

Altered structural connectivity in olfactory disfunction after mild COVID-19 using probabilistic tractography

  • Diógenes Diego de Carvalho Bispo,
  • Pedro Renato de Paula Brandão,
  • Danilo Assis Pereira,
  • Fernando Bisinoto Maluf,
  • Bruna Arrais Dias,
  • Hugo Rafael Paranhos,
  • Felipe von Glehn,
  • Augusto César Penalva de Oliveira,
  • Alexandre Anderson de Sousa Munhoz Soares,
  • Maxime Descoteaux,
  • Neysa Aparecida Tinoco Regattieri

DOI
https://doi.org/10.1038/s41598-023-40115-7
Journal volume & issue
Vol. 13, no. 1
pp. 1 – 12

Abstract

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Abstract We aimed to investigate changes in olfactory bulb volume and brain network in the white matter (WM) in patients with persistent olfactory disfunction (OD) following COVID-19. A cross-sectional study evaluated 38 participants with OD after mild COVID-19 and 24 controls, including Sniffin' Sticks identification test (SS-16), MoCA, and brain magnetic resonance imaging. Network-Based Statistics (NBS) and graph theoretical analysis were used to explore the WM. The COVID-19 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 WM in the COVID-19 group. Thus, patients with OD after COVID-19 had relevant WM 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.