Don't ignore your sense of smell

Hello friends,

Our sense of smell is our most undervalued sense. Last year I struggled with losing it for a few weeks.

The honeydew tasted like a sugary potato. That was my first clue that something was wrong.

I pride myself on having a keen sense of smell, sometimes to my disadvantage in putrid places. So you can imagine my dismay when, just days after returning from Thailand last year, I temporarily lost my sense of smell.

It was a rough time. As the American saying goes, the best part of coffee is waking up to smell it.

What could be done? I immediately bought a smell training kit online with vials of lemon, clove, eucalyptus, and rose, and whiffed them regularly morning and night. Fortunately, my sense of smell returned to normal within weeks, and I soon forgot about that chapter.

But many others aren't so lucky.

The Covid-19 pandemic thrust anosmia into public consciousness, revealing how common and distressing smell loss can be. Before the pandemic, many people didn't even know that infections could steal this sense. Now we know that weird misfiring of smell is a hallmark of Covid and its aftermath, with many never fully regaining what they've lost.

But what most people still don't realize is that losing your sense of smell might predict something far more serious than a viral infection.

As neurobiologist Michael Leon from the University of California, Irvine, recently said: "By middle age, your all-cause mortality can be predicted by your olfactory ability."

Let’s think about that for a moment.

This astounding claim seems to be backed by science. A landmark study following over 3,000 older people found that 39% of those with complete smell loss died within five years, compared to just 10% of those with normal smell.

This study tracked older adults (average age 76) who were otherwise living independently. Even after researchers accounted for existing health conditions, smoking, and other risk factors, smell loss remained a powerful predictor of mortality.

After accounting for other health factors, anosmia emerged as a surprisingly strong predictor of five-year mortality—putting it in the same category of risk as having a diagnosis of heart failure or severe diabetes.

To be clear, losing your smell doesn't doom you to an early death. Rather, it's a warning that something else might go wrong.

But the implications extend far beyond mortality statistics.

The connection goes beyond life and death. Losing the sense of smell has been linked to more than 100 conditions, from Parkinson's and Alzheimer's to cardiovascular disease and arthritis.

Perhaps most concerning for daily life: The worse your sense of smell, studies show, the worse you perform on cognitive tests.

But why would smell loss predict such dire outcomes?

The answer lies in our nose's unique wiring. Unlike other senses that route through the brain's central relay station, smells take the express lane directly to regions controlling emotion, memory, and decision-making. This superhighway explains why certain scents can instantly transport us to childhood memories.

When it breaks down, we lose a vital source of mental stimulation.

The olfactory system also serves as an early warning system.

Pathological proteins associated with neurodegenerative diseases accumulate in smell-related brain regions years before classic symptoms appear. Meanwhile, our nose's direct exposure to the environment makes it vulnerable to damage from pollution and pathogens, damage that may reflect broader health problems.

In other words, your nose is the canary in the coal mine for your health.

When it stops working properly, it might be telling you about inflammation lurking elsewhere, stem cells that aren't regenerating like they used to, or even everyday dangers you can no longer detect.

Given these implications, I find it remarkable how little we value this sense.

Surveys consistently show people would rather give up smell than their smartphones.

The good news is that smell training appears to work. Studies show that people who regularly sniff distinct odors can improve their olfactory sensitivity. The basic technique involves choosing four different strong scents—like rose, lemon, clove, and eucalyptus—and smelling each one for 15 seconds twice daily while concentrating on the memory of what they should smell like.

One particularly intriguing study found that people exposed to different scents while sleeping showed dramatic improvements in memory. Researchers had participants sleep with a device that released different fragrances throughout the night for six months. This resulted in remarkable 226% improvement in cognitive performance compared to the control group. Though we need more research to know if this works for everyone, the implications for brain health are tantalizing.

And here's something fascinating about the diagnostic power of smell working both ways.

Joy Milne, a Scottish nurse, noticed her husband's body odor had changed to a "musty" smell 12 years before he was diagnosed with Parkinson's disease. When she later attended a support group and realized everyone with Parkinson's had the same distinctive scent, she approached researchers who confirmed her ability.

She could identify Parkinson's patients by smell alone, even detecting one case well before clinical symptoms appeared.

So what should you do with this information? Start paying attention to your nose. If you notice persistent changes in your sense of smell (especially after age 50) don't dismiss them as "just getting older."

Consider a simple smell test: grab four different strong-smelling items from your kitchen (coffee, vanilla, lemon, garlic) and see if you can identify them with your eyes closed. If you struggle, it might be worth mentioning to your doctor.

Most importantly, remember that your sense of smell is providing your brain with constant stimulation and environmental information.

My own brief episode of smell loss gave me a glimpse into this hidden world. Now, when I smell my coffee brewing, I'm reminded that the signs of good health might be right under our noses.

Until next time,

Anirban

P.S. Have you ever noticed changes in your sense of smell?