Age and Subtle Cognitive Impairment Are Associated With Long-term Olfactory Dysfunction After COVID-19 Infection

Viviana Cristillo MD; Andrea Pilotto MD; Stefano Cotti Piccinelli MD; Nicola Zoppi MD; Giulio Bonzi MSc; Stefano Gipponi MD; Davide Sattin Psy; Silvia Schiavolin Psy; Alberto Raggi Psy; Michela Bezzi MD; Matilde Leonardi MD; Alessandro Padovani MD, PhD;

Disclosures

J Am Geriatr Soc. 2021;69(10):2778-2780. 

In This Article

Discussion

The prevalence of objective hyposmia in our cohort of hospitalized patients was 50%, definitively higher compared to prevalence of hyposmia in the general population in the sixth decade of age.[5] This prevalence fits well with recent reports adopting sniffing sticks in independent cohorts of SARS-CoV-2 patients.[6]

Older age was the most important factor associated with long-term hyposmia as patients older than 75 years of age were at three-fold risk of long-term hyposmia compared to younger subjects. Conversely, we failed to find an association between olfactory dysfunction and the severity of COVID-19, thus supporting the claim that hyposmia is independent from the degree of respiratory involvement.[7] Our study went also further, by showing an association between long-term hyposmia and cognitive impairment, after controlling for age, gender, and education. These findings corroborate the well-known association between subtle cognitive deficits and olfactory dysfunction in the older subjects.[8] Although the mechanisms underlying long-term central nervous system impact of SARS-CoV-2 are still unclear,[9,10] these preliminary results seem to suggest that older subjects with subtle cognitive deficits are a "vulnerable" population with a higher risk of long-term olfactory dysfunction.

We acknowledge that this study entails different limitations. First, we limited the observation to patients presenting with mild to moderate COVD-19; second, patients were evaluated only for orthonasal olfaction, whereas taste disorders were not assessed. Furthermore, no data about preexisting objective hyposmia or cognitive deficits were available, although we accurately excluded subjects with premorbid cognitive impairment or subjective hyposmia from the analyses.

Despite these limitations, the study underlined the high prevalence of objective hyposmia 6 months after COVID and identified age and subtle cognitive deficits as factors strongly associated with long-term olfactory dysfunction. Further studies evaluating the nature and progression of cognitive changes and olfactory function would be necessary over time.

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