To date, the mechanisms underlying the development of anosmia in a new coronavirus infection (COVID-19) are not completely recognized, and in some of those recovered, the disorders continue years later. Anosmia may be selective rather than total, manifesting as the inability to perceive specific odors.
OBJECTIVE
To study the occurrence and composition of selective anosmia to several monomolecular aromatic compounds in an open cohort of young individuals, including those with a history of COVID-19.
PATIENTS AND METHODS
The study systematically enrolled eligible participants instructed to inhale blotters infused with aromatic compounds, including monomolecular odorants, controls, and placebos. The participants completed a questionnaire that rated the intensity of the perceived odor for each substance on a 10-point scale and described the odor features in free form. The study involved 188 participants (median age was 19 years); after some questionnaires were excluded, data from 158 respondents was assessed (75.3% were females).
RESULTS
We observed prevalent selective anosmia to some substances (the percentage of participants identifying these substances as having a strong odor is provided in parentheses): methylcam phenylcyclohexanone — 41.1% (22.8%), methyl dihydrojasmonate — 29.7% (22.1%), patchouli ethanone — 22.8% (29.1%), galaxolid — 10.7% (31%), maltol — 7.0% (34.2%). The selective nature of anosmia is demonstrated by the fact that the same individuals classified other substances as intense. Only 10.8% of respondents experienced no reduction in sensitivity to any substances. No definitive correlation with the history of COVID-19 was found.
CONCLUSION
The prevalence of selective hyposmia and anosmia in the population is far higher than anticipated. The role of COVID-19 in the emergence of olfactory abnormalities is unclear. No substantial difference in selective anosmia to natural substances has been observed compared to non-natural substances. Assessing olfactory response to monomolecular odorants, rather than establishing a sensory threshold or identifying the odor, may represent a promising method for clinical research.
