Brain Sciences (Jul 2021)

Comparison of Brain Activation Patterns during Olfactory Stimuli between Recovered COVID-19 Patients and Healthy Controls: A Functional Near-Infrared Spectroscopy (fNIRS) Study

  • Roger C. Ho,
  • Vijay K. Sharma,
  • Benjamin Y. Q. Tan,
  • Alison Y. Y. Ng,
  • Yit-Shiang Lui,
  • Syeda Fabeha Husain,
  • Cyrus S. Ho,
  • Bach X. Tran,
  • Quang-Hai Pham,
  • Roger S. McIntyre,
  • Amanda C. Y. Chan

DOI
https://doi.org/10.3390/brainsci11080968
Journal volume & issue
Vol. 11, no. 8
p. 968

Abstract

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Impaired sense of smell occurs in a fraction of patients with COVID-19 infection, but its effect on cerebral activity is unknown. Thus, this case report investigated the effect of COVID-19 infection on frontotemporal cortex activity during olfactory stimuli. In this preliminary study, patients who recovered from COVID-19 infection (n = 6) and healthy controls who never contracted COVID-19 (n = 6) were recruited. Relative changes in frontotemporal cortex oxy-hemoglobin during olfactory stimuli was acquired using functional near-infrared spectroscopy (fNIRS). The area under curve (AUC) of oxy-hemoglobin for the time interval 5 s before and 15 s after olfactory stimuli was derived. In addition, olfactory function was assessed using the Sniffin’ Sticks 12-identification test (SIT-12). Patients had lower SIT-12 scores than healthy controls (p = 0.026), but there were no differences in oxy-hemoglobin AUC between healthy controls and patients (p > 0.05). This suggests that past COVID-19 infection may not affect frontotemporal cortex function, and these preliminary results need to be verified in larger samples.

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