The Cinderella Sense

How Covid has brought it to the world’s attention

Photo by 🇸🇮 Janko Ferlič on Unsplash

We have five basic senses, touch, sight, hearing, smell and taste. Smell is often referred to as the ‘Cinderella sense’, the one which has interested scientists least. Charles Darwin concluded in 1874 that olfaction (sense of smell) was “of extremely slight service” to mankind. Surveys regularly conclude that we value this sense least. A 2018 YouGov survey of 20,000 Americans, asked which of the five senses they would miss the most; 70% said sight, 7% hearing, in last place was smell with 2%. A separate one of 7,000, 16 to 22 year olds, concluded that more than half would prefer to disable smell rather than their smartphone or computer.

Covid can kill your smell

Somewhere between 44-77% of Covid patients experience a complete loss of smell (anosmia) in the acute stage of their illness. Even when evidence was pouring in from South Korea, China and Italy suggesting a link, it did not appear on the official symptoms list for months in the UK. Claire Hopkins, the head of the British Rhinological Society, told the New York Times she believed officials were slow to act partly because smell has never itself been regarded as “serious”.

Traditional medical perceptions are now changing because the Cars-coV-2 virus is particularly good at killing our sense of smell. In one hospital study, two-thirds of the 100 hospitalised patients regained their smell function within 6-8 weeks. But what about outside hospitals? Danielle Reed, associate director at the Monell Chemical Senses Center in Philadelphia, Pennsylvania, says half who lost their sense of smell still have problems and 5-10% have a total or near total loss of smell. In the UK alone, over 300,000 people are suffering from extended Covid smell loss. It’s significant and shouldn’t be ignored.

Covid anosmia is unusual. Unlike the common cold it happens immediately and without any congestion. A blocked nose stops odour-active molecules getting to the top of the nasal cavity. With Covid, an international collaboration have identified what is probably going on. The ACE2 proteins the virus needs to enter the body were not found on the olfactory neurons. But they were found next door on supporting cells which are likely to be damaged by the virus. Our immune response causes swelling which subsides when the virus has been dealt with. A clear route is restored for the aroma molecules and our sense of smell returns. When the inflammation is severe, the olfactory neurons can be damaged. In rare cases they could be destroyed making recovery unlikely.

What is taste?

It’s worth quickly clearing up any confusion over taste. We have 2-4,000 taste buds located on the tip and sides of our tongue. They allow us to differentiate between salty, sweet, sour and bitter tastes. A fifth has been added called umami or savoury. Spicy is not a taste and is ironically defined as a pain signal. 

Research undertaken by John McGann, a neuroscientist at Rutgers University-New Brunswick in New Jersey, has revealed that humans may be able to smell 1 trillion scents, just as many as super smellers like dogs. We have 400 smelling receptors in the olfactory cleft, not as many as Fido, but our much more complicated brain makes up for the difference. It’s those smells that provide food with those rich depths of distinctive flavours. Coffee is a good example.

Anyone for coffee?

I can speak from experience. I have hyposmia, a reduced sense of smell, as a result of concussion suffered during a football match. I loved coffee and rarely drank tea before my accident. I couldn’t drink another cup and here’s why. Imagine an ashtray full of cigarette butts and cold ash. Now add a small amount of cold water to it, just enough to make a sludge. Take a good sniff. That is what coffee smells like to me now - burnt, bitter and acrid. There are no subtle hints of vanilla or that rich roasting smell when coffee has been freshly ground. I also probably have a touch of parosmia, a distorted sense of smell (to go with my humour).

Experts believe it is also a sign of recovery, although the results, temporary or otherwise, can be far more disconcerting than mine. Some people complain that their favourite foods now smell like dead fish. Others, that they can’t stand the smell of their partner anymore. What if you have an acute sense of smell and something changes?

Joy Milne has a super power

10 years after Joy married Les, his smell changed. To her nose the male musk had gone, replaced with a nasty yeasty smell. She nagged him a bit about showering more often, but the smell didn’t go away. 14 years later, a doctor diagnosed Les with Parkinson’s disease. At some point after that shock, they decided to attend a support group meeting for sufferers and Joy reported that the smell in the room was overwhelming. Could it be that this incurable disease had a smell?

There was a lot of scepticism at first so a test was arranged. A group with Parkinson’s were asked to wear a white t-shirt overnight as were a control group. Joy was then given all the shirts to smell the next day. She was incredibly accurate, only making one mistake, identifying a person from the control group as a Parkinson’s sufferer. He was also later diagnosed.

As a result, researchers, including Perdita Barran at the University of Manchester have used Joy’s super smelling abilities to identify 10 compounds which are linked to Parkinson’s. They might not be able to cure it, but early diagnosis will help.

There’s more to smell than smell

Ann-Sophie Barwich a cognitive scientist who recently wrote, Smellosophy, explains the impact of losing this sense.

“You’ve basically got two effects with smell loss. You’ve got your own landscape of experience that’s changed; and there’s also the lack of a common social space.”

She relates it to a “sensory version of social media”. If you don’t participate, if you’re not on the platform, there are so many points of contact which are now completely inaccessible.

Hope in smell training

Covid recoverers and other smell sufferers can improve their sense of smell through regular training. You need a simple kit of 4 essential oils, rose, lemon, clove and eucalyptus. Make a note of what you can smell before you start, then compare notes after a couple of months. The idea is to smell each essential oil in turn, twice a day. Give each one a gentle sniff for about 20 seconds, before moving onto the next. All the details can be found on the abScent web site, https://abscent.org