Health news Health & Medical News Mystifying disorder affects sense of smell

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Mystifying disorder affects sense of smell

I can't wake up and smell the coffee.

I can't smell the roses, either, the ones that I bought from a man who wrapped them in crisp white paper and that shed their aromatic petals onto our dining room table.

I am not speaking in metaphor here. I'm talking about a total olfactory wipeout.
It happened four years ago. One day, the world was my snuffbox: Ginger sputtering in olive oil, peppermint gum, pinot noir, the cat's litter pan, my daughter's Tea Tree-scented shampoo. The next day: nothing.

My sense of smell wasn't muted, the way it is with a bad cold. It was gone. Kaput. Like when a fuse blows in the basement, and no matter how much you toggle the wall switch, the light will not turn on.

There's a name for my affliction: anosmia. There's also a Wikipedia entry, a foundation with a message board, and plentiful company - about two million Americans suffer taste and smell disorders. We're numerous, but not noticeable; unlike a blind woman with her guide dog, unlike the deaf speaking volumes with their hands, the anosmic appear, well, the same as you and me.

The bad news about anosmia is that the human olfactory system - how odor travels from that brimming cup of Sumatra to your brain, which processes the news in a microsecond and thinks "coffee" - is still largely a mystery.
"The human nose is not understood," says Richard Doty, director of the University of Pennsylvania's Smell and Taste Center. "And there's not a lot of sympathy out there for smell disorders. It's not a broken leg; it's not visible."

The good news is that Doty and others are starting to make sense of scent.

They are learning that olfaction isn't a one-size-fits-all operation; that is, a rose (or a pheromone from uncastrated boars) doesn't carry the same odor for everyone. To some, the smell of skunk evokes fresh-squeezed lemonade, not the astringent reek that makes most people want to run.

"The foundation of smell is genetic," says Charles Wysocki, a neuroscientist at the Monell Chemical Senses Center in Philadelphia. "But experience and environmental factors also affect how people respond to smell. To the swine farmer, the pit under the barn smells like money. A child who experiences the smell of roses on a walk with his mother . . . that's much different from the child whose first experience with roses is at his mother's funeral."

New research on olfaction shows that it involves the brain as much as the nose, and, like the rest of the brain, the system is constantly adapting. In some cases, experiments have shown, people can train their noses to know better.

Here's what scientists understand about the process of smell: Odor molecules, from a Jersey tomato, say, enter your nose and travel up to a patch of membrane called the nasal epithelium, where each odorant locks into a receptor neuron.

Humans have about 350 different types of odor-receptor neurons (mice, those savvy sniffers, have 1,000), each designed to fit specific types of odor molecules. It's a lock-and-key system, but a complicated one, with multiple keys (the odor molecules) able to fit into several types of neurons (the locks). Since most smells are complex - a wine might have notes of blackberry, citron, and oak - it's the overall pattern of molecules binding to odor receptors that we recognize as cabernet, vanilla, or sweat.

The receptor neurons - some of the only neurons that continuously regenerate - then fire electrical signals up to the olfactory bulb, the brain's smell-processing center. From there, other signals fan out to parts of the brain involved with emotion, memory, and cognition. Scientists are just beginning to understand how that happens.

"There are circuits in the olfactory bulb that very quickly decide, 'OK, this is a nice coffee,' or 'This does not smell good,' " says Diego Restrepo, codirector of the Rocky Mountain Taste and Smell Center at the University of Colorado. Different parts of the brain swiftly determine "not just how does it smell, but what does it mean" - a survival strategy that keeps us safe from moldy food, toxic leaks, and fire.

That's what happens when the system works. But what about anosmics like me? Some degree of smell loss is inevitable and age-related; about 75 percent of people over age 80 have lost some smell sensitivity. Younger people can lose their sense of smell if odor molecules are blocked by nasal inflammation - the root of my problem - or if a virus has damaged the receptors. Sinus disease or upper respiratory infections are the most common causes.

Head trauma can also obliterate smell. Molly Birnbaum was 22, a recent college graduate and aspiring chef, when she was hit by a car while jogging. Her head shattered the windshield, and when her brain jounced against the inside of her skull, it sheared off the olfactory neurons.

Birnbaum, who lives in Boston, remembers the moment she realized that, along with a broken pelvis and torn knee tendons, she had no sense of smell. "My stepmother had baked an apple crisp. Everyone was exclaiming about the smell - the apples, cinnamon, and butter - and I couldn't smell it," she says.

"I felt devastated. I wanted nothing more than to be a chef. Without a sense of smell, that was impossible. I couldn't perceive flavor." Several doctors told Birnbaum there was little hope, after such a traumatic injury, that her olfactory neurons would regenerate. But they did: About four months after her accident, Birnbaum could smell rosemary. Chocolate was next. Gradually, over five years, the whole palette of odors returned.

Birnbaum chronicled her experience in a memoir, Season to Taste: How I Lost My Sense of Smell and Found My Way, published in June. She interviewed scientists at Monell and elsewhere, enrolled in perfume school in France, and began to cook again. She also talked with other people who suffered from anosmia.

"It made me realize I was not alone in feeling that my world had turned upside-down . . . We don't realize the power of smell until it's gone."

I know exactly what she means. Without the ability to smell, I can't tell if my favorite shirt is too rank to wear again, if the guacamole has gone bad, or if the chocolate-chip cookies are starting to scorch in the oven. It's difficult to describe the absence of odor: a blank page? An empty room? A white sink scoured clean? My contact lenses bring the visual world into sharper focus; if I can't hear the DVD, I turn up the sound. But there is no device to jack up the intensity of scent.

A year ago, I experienced brief, ecstatic relief: A fusillade of medicine, including oral steroids and two different nasal sprays, succeeded in restoring my sense of smell. After three days of treatment - and despite the side effects of the steroids, which left me thirsty, flushed, and irritable - I hugged my mother and smelled her perfume for the first time in years.

A week later, I took the real olfactory test: I strolled down Eighth Avenue in New York City, inhaling honey-roasted cashews, grilled kielbasa, and warm, yeasty pretzels. Overripe banana mixed with bus exhaust stirred with french fry oil layered with stale beer from a shattered bottle of Sam Adams by the curb.

Memories returned, tethered to particular smells. A stack of hot tomato pies vaulted me back to nights I spent copy-editing my college newspaper, when we gorged ourselves at 9 p.m. on pizza so greasy we had to blot it with paper towels.

But the rush of scent was short-lived. "The secret of maintaining your sense of smell after treatment is pretty intractable," says Doty of Penn's Smell and Taste Center. Only about 20 percent of the patients he sees - those with some loss of smell - return to a normal range. Of those with total anosmia, only 10 percent recover. Systemic steroids can shrink inflammation in the nose, but unless you stay on the medicine - not advisable, since steroids have a host of side effects - the inflammation tends to come back.

Birnbaum's experience gives me hope, though. So does some of the newest research at Monell, showing that even older people with reduced senses of smell can boost their sensitivity with a kind of olfactory calisthenics.

In a recent pilot study involving participants over 65, some sniffed jars of "complex smells" - licorice, wintergreen, banana, and rose - each morning and evening for a period of 12 weeks. Researchers tested their ability to detect those smells at the start of the study, at six weeks, and at the end; about half of those who had done the sniffing exercises showed improvement. "Olfaction is a learned sense," says Beverly Cowart, the Monell psychologist who conducted the pilot study and will soon launch a similar experiment involving younger participants. "Exposure to odors can lead to increased odor sensitivity."

A similar study in Germany, published in Laryngoscope in 2009, also showed some positive effects from "smell training" with odors of rose, eucalyptus, lemon, and cloves.

Last week, while making jambalaya, I leaned over the kettle where chopped onions, carrots, and celery sizzled in olive oil. Steam enveloped my face, but I got zilch from the aromatic contents of the pot. Perhaps I'll try what the good doctors order, though: line up some jars from the spice cabinet - cumin and cayenne, cinnamon and sage - and attempt to sniff my olfactory system awake.

Source: Philly.com Health News , By Anndee Hochman"For The Inquirer"

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