The COVid cohORT on Smell loss

Smell loss is one of the most frequent symptoms -and predictor- of Covid-19, can be long-lasting and have devastating impact on eating behavior and daily life. In particular, patients often report that after a period of smell loss (anosmia), they develop a distorted sense of smell (parosmia). Yet the course and frequency of this conversion is unknown, and treatment or advice and prognosis is currently still lacking. Therefore, we will investigate both the natural course of smell alterations in relation to Covid-19 and differences in neural activity between anosmia and parosmia. This will be done in a prospective cohort study. A subset of patients will be included in an observational case-control study with one time follow-up, where we will perform neuroimaging. Every 3 months, patients will be objectively tested on their smell and taste ability, including parosmia. In addition, patients will fill out online questionnaires related to their smell and taste ability, trigeminal sensations, eating behavior, quality of life, and perform an at-home test every month. For the neuroimaging part, patients will participate in two scanning sessions (upon inclusion, and follow-up after 6 months), including structural and functional MRI in which patients are exposed to different olfactory stimuli.

We expect that smell and taste function will be decreased shortly after infection, but that smell and taste function will recover over time. Part of the patients will develop parosmia. Smell loss due to a Covid-19 infection will affect structure and function of olfaction-related areas in the brain.

The study involves a maximum of 20 test sessions (T0 – T12, plus the additional objective tests at T0, T3, T6, T9 and T12, plus 2 neuroimaging sessions). Test sessions will take place each month.

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