Study of the Evolution of Olfactory Disorders in Patients With Persistent Loss of Smell Following COVID-19

Summary

The COVID-19 pandemic is a novel medical challenge, particularly because of the systemic nature of this disease. Indeed, COVID-19 affects several organs and systems at once. The brain is affected in several ways: direct infection of nerve cells by SARS-CoV-2, inflammation of the central nervous system, severe systemic inflammation damaging nerve cells, global cerebral ischaemia related to respiratory failure, thromboembolic events related to increased intravascular coagulation and severe psychological stress. As a result, COVID-19 sometimes manifests as neurological and neuropsychiatric symptoms such as dizziness, sleep disturbances, cognitive deficits, delirium, or severe depression.

Sudden loss of smell is a common symptom associated with COVID-19 and SARS-CoV-2 infection of neurons in the olfactory system has been reported in both hamsters and humans. The vast majority of COVID-19 patients recover their olfactory function within a few weeks. However, a significant minority of infected individuals (1 in 5 cases) still suffers from olfactory disorders (anosmia, hyposmia and/or parosmia) several months after the primary infection. These olfactory disorders are frequently associated with depressive behaviour and cognitive complaints. In PET scans, it is even possible to correlate this cognitive dysfunction with hypometabolism of certain brain regions, including the olfactory gyrus.

This project proposes, during one year, to evaluate and follow the evolution of the olfactory capacities of patients suffering from persistent smell disorder since one year (+/- 4 months) following COVID-19. The issue is to study the link between viral persistence in the olfactory sensory organ, chronic inflammation, and central damage to the olfactory system. The follow-up of the evolution of olfactory and neurocognitive capacities, in an integrative way by means of molecular, physiological and behavioural approaches, will inform us on the specificities of "COVID-long" and on the level of peripheral and/or central damage of the olfactory system.

Conditions

• SARS-CoV-2 Acute Respiratory Disease

Interventions

OTHER

Clinical examination

The investigator will conduct a clinical examination to rule out other causes of olfactory impairment independent of COVID-19. The investigator will also collect the following information: socio-demographic data (age, sex, blood type, weight, height, etc.), history of olfaction disorder symptoms, past or current treatments received and tobacco/alcohol consumption.

OTHER

Blood collection

12ml-blood sample

OTHER

Olfactory evoked potentials

Olfactory evoked potentials will be recorded during olfactory tests.

OTHER

Brushing of olfactory slits

collection of olfactory slits cells.

OTHER

Neurological examination and neuropsychological assessment

* MOCA, BREF * CVLT * WAIS IV, MEM III * Right-side and left-side empan, Trail Making Test A and B (TMT), verbal fluency tests, PASAT, Attention Assessment Test * Benton's Line Judgement, VOSP * Assessment of psychological status, fatigue and screening for psychiatric comorbidities: depression \& anxiety scales (HAD scale, mADRS depression scale, STAI anxiety scale), Fatigue Severity Scale.

OTHER

Nasal endoscopy

Nasal endoscopy

OTHER

Assessment of olfactory and taste functions

* scales: VAS and TSS * Sniffin Stick test

Sponsors & Collaborators

• Hopital Lariboisière

  collaborator OTHER

• Institut Pasteur

  lead INDUSTRY

Principal Investigators

• Pierre-Marie Lledo, Prof. · Institut Pasteur

Study Design

Allocation

NA

Purpose

BASIC_SCIENCE

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

18 Years

Max Age

55 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2022-06-20

Primary Completion

2024-10-15

Completion

2024-10-15

Countries

• France

Study Locations