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;


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

In This Article


A total of 168 patients hospitalized for mild to moderate COVID-19 were evaluated at 6 months after discharge. Of these, 106 patients were assessed in presence through a standardized assessment. Five patients (5.7%) were excluded from the study for allergic rhinitis, resulting in a final dataset of 101 patients.

The Sniffin' Sticks test[4] identified 50 patients with an abnormal score ≤ 8, including 11 patients with severe (score < 4) hyposmia (4/11 of them reported subjective olfactory dysfunction) (Table 1). Patients with subjective hyposmia exhibited lower Sniffin' Sticks total score (5.3 ± 3.5 vs. 8.1 ± 2.4, p = 0.012) but three of them exhibited normal scores. Conversely, patients with long-term subjective hypogeusia exhibited similar Sniffin' Sticks total scores compared to subjects without complaints (7.8 ± 2.5 vs. 7.8 ± 2.8, respectively, p = 0.70). Hyposmia and hypogeusia reported during hospitalization did not predict long-term objective hyposmia (odds ratio [OR] 1.1; 95% confidence interval [CI] 0.75–1.7) or subjective hyposmia (OR 1.03; 95% CI 0.70–1.5, p = 0.52).

Compared to patients with normal olfactory function, those with objective hyposmia were older (68.2 ± 11.3 vs. 58.2 ± 12.1 years, p = <0.001) but exhibited similar comorbidity score at admission and during hospitalization and did not differ for duration of hospitalization, oxygen therapy, and severity of COVID-19 (OR 1.5; 95% CI 0.83–2.7, p = 0.10). Age was confirmed as the only predictor of long-term objective hyposmia in logistic regression analyses (Wald 6.4, exp[B] = 0.09, p = 0.01); subjects older than 65 years exhibited a 1.86 increased risk of hyposmia (95% CI 1.19–2.9) and subjects older than 75 years of 2.67 (95% CI 1.10–6.5).

No difference of either self-reported neurological symptoms at the neuro-checklist or objective neurological signs was documented between patients with normal olfactory function and hyposmia (Table S1). Patients with hyposmia exhibited lower MoCA (Montreal Cognitive Assessment) total score (23.2 ± 3.4 vs. 25.7 ± 2.5) compared to subjects with normal olfactory function in logistic regression analyses adjusted for age, sex, and educational levels (Wald 5.8, exp[B] = 1.2, p = 0.01).