A comparison of post-Covid-19 and Parkinson’s disease olfactory disorders
DOI:
https://doi.org/10.61989/fbb8ad35Keywords:
Parkinson’s disease, COVID-19, Sniffin’ Sticks Test , speech therapy, olfaction, olfactory disordersAbstract
Context. Olfactory disorders, long regarded as secondary, gained new visibility following the COVID-19 pandemic. At the same time, dysosmias are now recognized as a major prodromal sign of idiopathic Parkinson’s disease (IPD).
Objectives. This study aims to compare subjective and objective olfactory profiles in patients with IPD and post-COVID-19 patients, in order to identify discriminant markers and better understand the underlying mechanisms of dysosmia through a psychophysical approach.
Methods. Two groups of 20 patients were matched for age and sex : one group with early-stage IPD (disease duration < 3years), and one post-COVID-19 group presenting olfactory disorders. Both groups were recruited from Assistance Publique – Hôpitaux de Marseille. The Sniffin’ Sticks Test (SST), a reference test for olfaction, was administered to all patients (with a detection threshold score, a discrimination score, an identification score, and a total score). A clinical interview was also conducted to collect relevant data, complemented by clinical scales (EVA, HAD, Starkstein, RBDQ).
Results. Our findings demonstrate that olfactory disorders related to IPD and COVID-19 present different profiles : IPD patients exhibit more diffuse olfactory impairment, with lower discrimination and total score, whereas post-COVID-19 patients report stronger subjective complaints and more qualitative disturbances (parosmias and phantosmias). Combining two measures : EVA and discrimination, or EVA and total score, reliably distinguishes the two groups. Significant correlations were also found between certain olfactory performances and clinical variables in patients with IPD (age, disease duration, motor score UPDRS-III, REM-sleep behavior disorders, anxiety and apathy).
Conclusion. This study highlights two distinct olfactory profiles depending on etiology. It also suggests that olfactory rehabilitation protocols developed for COVID-19 could represent a complementary approach to the overall speech and language therapy management of patients with IPD, particularly through sensory stimulation.
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Copyright (c) 2026 Léa Guerra, Laurane Bessi, Corentin Gaillard, Yoran Marchi, Thomas Radulesco, Justin Michel, Jean-Philippe Azulay, Emmanuelle Albert, Stephan Grimaldi
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