Alterations of the amygdala in post-COVID olfactory dysfunction

Area of Science:

• Neuroscience
• Medical Imaging
• Infectious Diseases

Background:

• Olfactory dysfunction (OD) is a common COVID-19 symptom, often transient but sometimes persistent.
• Central nervous system involvement is increasingly implicated in persistent post-COVID OD.
• Understanding the neural underpinnings of persistent OD is crucial.

Purpose of the Study:

• To investigate white matter integrity in olfactory processing regions using diffusion tensor imaging (DTI).
• To compare brain structural connectivity in patients with persistent post-COVID OD versus controls.
• To explore potential links between brain changes, OD, and psychological symptoms.

Main Methods:

• Diffusion tensor imaging (DTI) MRI was used on 61 participants (31 with post-COVID OD, 30 controls).
• Region of interest (ROI)-based analysis and voxelwise statistics were applied.
• Fractional anisotropy (FA) and radial diffusivity (RD) were measured in olfactory-related brain areas.

Main Results:

• Higher FA in the left amygdala and higher RD in the right amygdala were observed in the post-COVID OD group.
• Patients with persistent OD reported higher scores for depression and anxiety.
• Olfactory-related brain regions (amygdala, putamen, piriform cortex) showed associations with psychological scores.

Conclusions:

• Persistent post-COVID OD is associated with altered white matter integrity in olfactory brain regions.
• Changes in myelination or axonal diameter in the amygdala may underlie persistent OD.
• A potential interrelationship exists between persistent post-COVID OD, depression, and anxiety, warranting further investigation.