Olfaction and anosmia: From ancient times to COVID-19

Olfaction, one of our five main qualitative sensory abilities, is the action of smelling or the capacity to smell. Olfactory impairment can be a sign of a medical problem, from a benign nasal/sinus problem up to a potentially serious brain injury. However, although clinicians (neurologists or not) usually test the olfactory nerves in specific clinical situations (for example, when a neurodegenerative disorder is suspected), they may omit such tests in many other situations. With the recent COVID-19 pandemic, the resurgence of anosmia has reminded us of the importance of testing this sensorineural function. We retrace here the main historical steps and discoveries concerning olfaction and anosmia. [Display omitted] •Olfaction is an important physiological function, its impairment contributing to reduce quality of life.•For centuries, numerous anatomical and physiological studies have contributed to a better understanding of olfaction.•Olfactory dysfunction may be due to various causes, neurological or not.•A link between olfaction and neurodegenerative disorders was established.•With the current pandemic (COVID-19), new interests in olfaction and new hypothesis emerged.