New Hope for People With No Sense of Smell

To avoid seeing something they don’t want to see, children often cover their eyes with their hands. Similarly with their ears. Older children might explain that they’re pretending to be blind or to be deaf.

What about when they encounter an unpleasant stench? Perhaps, analogously, they’ll pinch their noses shut. But if you’d ask them what they’re pretending to be, chances are you’d be met by a blank stare.

Blind and deaf (as well as partially-sighted and hard of hearing) are familiar terms. Few adults would have any difficulty explaining that they refer to a complete or partial loss of the senses of sight or hearing.

Yet the terms "anosmia," referring to the loss of the sense of smell, and "hyposmia" (the partial variant) are little known. Why the big difference?

Measuring and Testing

Scientists have been experimenting with measuring aromas since the 18th century. The first "olfactometer" was developed a century ago by the Dutch physiologist Hendrik Zwaardemaker.

Devices for measuring aromas depend on a sensor that responds differently to different concentrations of aromatic substances in the environment. Over the years, techniques have improved enormously. Thus, while early experiments used chemically coated electrodes, recent studies use living cells and "neurochips."

Commercial aroma-sensing devices have been available for years. They are used in the food industries, for testing whether a product is fresh, ready to eat, or has gone "off." In medicine, it’s also used to test for bad breath, which may be a sign of something serious.

Yet unlike with sights or with sounds, there’s no way for laypeople to record aromas. We go into the countryside and photograph the rolling hills. We record the chirping of the birds. We love the scent of the new-mown hay. But we can’t record it.

Also unlike seeing or hearing, people’s olfaction is not routinely measured. Loss of sight or of hearing are considered significant disabilities. Children are typically screened at an early age and there are well-established tests for both sight and hearing.

Experience teaches that as we get older, our eyes and our ears perform less well. Statistics confirm that the prevalence both of defective hearing and vision increases with age. Each condition affects about 6 percent of middle-aged Americans.

What about olfaction? We might be less aware of it, but this too declines with age. Though no statistics are collected routinely, it’s been estimated that 13 million adults in the United States are affected.

Assistive Devices

In wealthy societies, when we experience problems of sight or hearing, testing is easy to arrange. And if there is a problem then—provided we or our insurance can cover the cost—we know what we need.

Spectacles have been around for centuries. Electrical hearing aids were developed at the beginning of the 20th century, though there had been simple mechanical things (such as ear trumpets) for much longer. With the development of the audiometer, hearing aids could be calibrated to correct individual patterns of hearing loss. Advances in science, technology, and surgical technique are leading to increasingly sophisticated devices and procedures (cochlear implants for example, or corneal grafts).

For olfaction, the measuring technology (analogous to the audiometer) exists. So why can’t you get an assistive device equivalent to the hearing aid or the cochlear implant?

Hierarchies of the Senses

It can’t be because the loss of a sense of smell doesn’t affect people. There’s evidence from various studies that loss of smell can seriously affect quality of life. It does so in a number of ways, ranging from insensitivity to personal hygiene, to difficulties in preparing food, and inability to detect signs of danger (such as poisonous fumes). So why isn’t there any kind of assistive technology?

Perhaps the answer is partly to do with how the experiences associated with olfaction differ from those associated with sight or hearing. In the 18th century, philosophers decided that whereas sight was the sense associated with reason and civilization, smell was something more animal.

Smell is associated with bodily things—a baby’s recognition of its mother’s smell, for example. Less familiar, research has shown that women’s tears contain chemicals that decrease sexual arousal in men.

Scent Essential Reads

Are Scent Preferences Universal?

Sniff Test: Research Is Unraveling The Mysteries of Smell

In many cultures, odor is a mark of "us" and "them." People who "aren’t us" are said to smell differently. We don’t talk much about odors—except the ones we buy in bottles. But historians and anthropologists who study the senses have shown that this hierarchy of senses actually changed over time and differs between cultures.

Recognition, Post-Pandemic

The lack of a "smelling aid" was not because sufferers don’t want one. An Austrian study carried out in 2018 found that more than 30 percent of people suffering from anosmia said they would want it. But prior to the COVID-19 pandemic, their preferences were scarcely acknowledged either by the medical profession or by industry.

That changed when about 50 percent of people diagnosed with COVID-19 complained of loss of the ability to smell. In many cases, this persists as a symptom of long COVID. Hypotheses as to how and why this might be are now emerging

A possibly unexpected consequence of the pandemic is growing interest in developing an olfactory prosthetic, a bionic implant. Technology and surgical techniques are moving forwards, offering new hope to people who’d like to smell the roses again.