Taste dysfunction after COVID-19: Analysis with functional near-infrared spectroscopy

Area of Science:

• Neuroscience
• Medical Imaging
• Infectious Diseases

Background:

• COVID-19, originating in China in December 2019, has become a global pandemic.
• Taste dysfunction (dysgeusia) is a reported symptom in some COVID-19 patients.
• Understanding the neurological underpinnings of COVID-19-related dysgeusia is crucial.

Purpose of the Study:

• To investigate differences in functional near-infrared spectroscopy (fNIRS) brain activity between convalescent COVID-19 patients and healthy controls.
• To explore potential correlations between fNIRS findings and the pathomechanism of dysgeusia in COVID-19.

Main Methods:

• A cohort of 16 participants (8 convalescent COVID-19 patients, 8 healthy controls) underwent fNIRS.
• Brain activity was assessed by analyzing changes in oxyhemoglobin (oxyHb) concentration in the cerebral cortex.
• Stimulation involved a taste stimulus (citric acid solution).

Main Results:

• No statistically significant differences were found in the amplitude of oxyHb concentration changes between the COVID-19 and control groups.
• fNIRS detected unexpected, strong stimulation in the visual cortex in response to the taste stimulus.
• This visual cortex stimulation occurred concurrently with taste cortex activation, a novel finding.

Conclusions:

• The study found no significant differences in cerebral cortex oxyHb dynamics between convalescent COVID-19 patients and healthy controls.
• The role of the occipital cortex in taste perception warrants further investigation.
• fNIRS may reveal novel aspects of sensory processing, even in the absence of group differences.