# Long-term effects of SARS-CoV-2 infection in patients with and without chemosensory disorders at disease onset: a psychophysical and magnetic resonance imaging exploratory study

## TL;DR

This study explores long-term effects of SARS-CoV-2 on smell and taste in patients with and without initial chemosensory issues, using tests and brain imaging.

## Contribution

The study provides new insights into long-term chemosensory impairments and brain volumetric changes in post-COVID-19 patients.

## Key findings

- Olfactory impairment was more severe in patients with initial chemosensory issues.
- Dysgeusia was only present in patients with initial chemosensory issues.
- Brain volumetric analysis showed a significant difference in the right caudate nucleus among groups.

## Abstract

A preserved sense of smell and taste allows us to understand many environmental “messages” and results in meaningfully improvements to quality of life. With the COVID-19 pandemic, it became clear how important these senses are for social and nutritional status and catapulted this niche chemosensory research area towards widespread interest. In the current exploratory work, we assessed two groups of post-COVID-19 patients who reported having had (Group 1) or not (Group 2) a smell/taste impairment at the disease onset. The aim was to compare them using validated smell and taste tests as well as with brain magnetic resonance imaging volumetric analysis. Normative data were used for smell scores comparison and a pool of healthy subjects, recruited before the pandemic, served as controls for taste scores. The majority of patients in both groups showed an olfactory impairment, which was more severe in Group 1 (median UPSIT scores: 24.5 Group 1 vs 31.0 Group 2, p = 0.008), particularly among women (p = 0.014). No significant differences emerged comparing taste scores between Group 1 and Group 2, but dysgeusia was only present in Group 1 patients. However, for taste scores, a significant difference was found between Group 1 and controls (p = 0.005). No MRI anatomical abnormalities emerged in any patients while brain volumetric analysis suggested a significant difference among groups for the right caudate nucleus (p = 0.028), although this was not retained following Benjamini–Hochberg correction. This exploratory study could add new information in COVID-19 chemosensory long-lasting impairment and address future investigations on the post-COVID-19 patients’ research.

The online version contains supplementary material available at 10.1007/s10072-024-07429-4.