Prefrontal dysfunction in post-COVID-19 hyposmia: an EEG/fNIRS study

Area of Science:

• Neuroscience
• Infectious Diseases
• Cognitive Science

Background:

• Long COVID-19 syndrome frequently causes cognitive dysfunction and mental fatigue.
• Persistent hyposmia (reduced sense of smell) is a common symptom in long COVID-19 patients.
• Understanding the neurophysiological basis of these deficits is crucial for effective management.

Purpose of the Study:

• To correlate cognitive, neurophysiological, and olfactory function in individuals with a history of SARS-CoV-2 infection and persistent hyposmia.
• To investigate prefrontal cortex function using electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) in post-COVID-19 patients.
• To assess cognitive performance using standardized tests.

Main Methods:

• Integrated EEG-fNIRS system used during P300 odd-ball and Stroop tasks.
• Olfactory function assessed using the Sniffin' Sticks test.
• Cognitive function evaluated with the Montreal Cognitive Assessment (MoCA) and Frontal Assessment Battery (FAB).

Main Results:

• Post-COVID-19 patients exhibited lower oxyhemoglobin concentration in the prefrontal cortex during the Stroop task.
• A reduction in P3a response amplitude was observed in the post-COVID-19 group.
• Patients performed significantly worse on MoCA, Sniffin's Sticks test, and Stroop task response latency.

Conclusions:

• Post-COVID-19 patients with persistent hyposmia show mild prefrontal function deficits up to 4 months post-infection.
• These subtle deficits may have long-term implications for quality of life and cognitive health.
• Continued monitoring of cognitive impairments in long COVID-19 is essential.