Barrie Smith was diagnosed with Parkinson's Disease in his 50s, but 18 years before he was given his diagnosis, he developed a very strange and permanent symptom. One day he detected "a strong smoky smell, like burning wires", he says. Since then, he has never smelt anything again. At the time, flummoxed, Smith's doctor attributed the loss of his sense of smell to his scuba diving, as deep diving is known to sometimes cause smell impairments. If only the doctor was right.

Smell loss can have sinister origins beyond scuba diving, and in Smith's case, that proved to be true. In today's world, most would automatically attribute the loss of smell to Covid-19, but it is also a common symptom of neurodegenerative diseases, including Multiple Sclerosis, Parkinson's disease and Alzheimer's disease.

— Read more about efforts to develop smell-related diagnostic tests (and how to retrain your olfactory system) in How your sense of smell predicts your overall health at BBC.

If smell was ignored before, off in the hinterlands, you could say that Covid put it on the map. But studying smell, scientist after scientist told me, had already reshaped the way they thought about the world and their place in it. They went, they said, from thinking of smell as a “bonus sense” to a dominant one, and “from a secondary sense to one of the primary things that influences our life.” The geography had shifted even as they were working to chart it.

— That's the last paragraph of a very long article about the Covid pandemic and olfaction, written by Brooke Jarvis, who has anosmia. Even if, like me, you feel you've now read enough on the subject of Covid-related loss of smell, you might want to read this one (or listen to the 55 minute audio recording). See What Can Covid-19 Teach Us About the Mysteries of Smell? The virus’s strangest symptom has opened new doors to understanding our most neglected sense. at The New York Times. Hat tip to Kevin!