Taste and Smell
By JANE E. BRODY
New York Times: April 18, 2011
Dr. Ronald DeVere, a neurologist in Austin, Tex., was baffled. In 1995, after recovering from a viral infection, something happened to his sense of smell. Fresh milk smelled sour, the dirty dog pen smelled good, and other odors couldn’t be detected at all
After weeks passed without improvement, he consulted experts at the University of Pennsylvania Smell and Taste Center, one of 11 such clinics now scattered around the country. Tests there showed that as a result of his illness, he’d lost 70 percent of his ability to smell.
In the years since, Dr. DeVere has recovered much of his ability to smell and taste. But the experience inspired him to open his own clinic for smell and taste disorders and, most recently, to write a book, “Navigating Smell and Taste Disorders” (Demos Health), about this poorly understood and often unrecognized problem.
In an interview, Dr. DeVere said he hoped the book would help not only patients with smell and taste disorders but also their physicians, most of whom know little about these problems, he said, and often tell sufferers that “nothing can be done — you’ll have to live with it.”
The book was written with his sister-in-law, Marjorie Calvert, an accomplished cook who provided a food preparation guide and dozens of recipes — some contributed by patients — that can help restore dining pleasure to those affected. Taste is mostly a result of odor detection, so the recipes emphasize spice, texture and temperature, sensations that remain unimpaired even when smell malfunctions.
You’ve no doubt experienced a temporary disruption in smell and taste while suffering from a cold or sinus infection. Try to imagine your life if the problem lasted indefinitely and you could no longer enjoy the flavor of an orange or chocolate or taste the difference between chicken and steak.
But smell and taste disorders can affect more than the ability to “smell the roses” in life and toenjoy food. Also affected is the ability to detect and correct unpleasant smells, like body odor or a dirty diaper in need of changing. For people like professional cooks and firefighters, the problem can force an occupational switch.
Most important, smell disorders can be downright dangerous for those who cannot detect the odor of smoke, burning or spoiled food, natural gas or other noxious aromas.
An Underrecognized Problem
While reliable statistics are hard to come by, several million Americans are thought to suffer from the major smell disorders: hyposmia, a reduced ability to detect certain odors; anosmia, an inability to detect any odors at all; or dysosmia, in which pleasant odors can smell foul or vice versa.
Most people who think they have a taste disorder, usually because food has lost its flavor, turn out to have a smell problem, according to Richard M. Costanzo, a neurophysiologist at Virginia Commonwealth University. The smell disorders clinic there receives regular inquiries from distressed patients; one of them said his inability to taste food flavors was “a very life-altering experience, and most normal people cannot understand the impact it has on one’s life.”
There are many common causes. In addition to viral infections like colds and flu, they include disorders of the nose (for example, polyps) or sinuses; injuries to the nose or head; medications like blood pressure drugs, antibiotics, cholesterol-lowering drugs, antidepressants and cancer chemotherapy; radiation therapy of the head and neck; exposure to toxins like formaldehyde and pesticides; smoking and alcohol abuse; diseases of the thyroid, kidneys, liver or pancreas; and neurological disorders like Parkinson’s disease, Lewy body disease, multiple sclerosis and various kinds of dementia.
Half of all people with diabetes have a diminished sense of smell and taste, and 90 percent of those with Alzheimer’s disease have impaired smell capacity, Dr. DeVere said.
By far the leading cause — and the one least often recognized — is advancing age. Whereas only 1 percent to 2 percent of young people are affected, a quarter of those over 55 and nearly two-thirds of those over 80 have a diminished sense of smell.
But unlike vision or hearing loss, which is often apparent to others, if not to the afflicted person, a loss of smell sensitivity with age is often undetected because it occurs gradually. The result can be a diminished interest in food and gradual weight loss, or a tendency to over-season foods with salt or sugar, which may impair control of high blood pressure or diabetes, common problems in the elderly.
Depending on the cause of a smell disorder, therapeutic possibilities include treatment with nasal decongestants, antihistamines, or antibiotics; surgery to remove nasal polyps; use of a nasal saline solution; correction of hormonal or nutrient deficiencies; and stopping smoking.
Dr. DeVere said that over time smell disorders may gradually diminish in intensity, as his did. Nonetheless, Dr. Costanzo said: “We have to be fair to patients. There’s no magic bullet. Some smell problems are treatable, most are not.”
Especially challenging are those that result from head injuries, whether minor or severe, that disrupt the function of the body’s smell receptors — olfactory nerve cells that lie outside the brain. These cells pick up odor molecules high in the nose and transmit scent messages to the brain’s olfactory bulb, he explained.
A head blow can injure or tear olfactory nerves. Damaged olfactory nerve cells can regenerate, but don’t always reconnect properly in the brain. Dr. Costanzo and colleagues are working on grafts and transplants that may one day overcome current treatment limitations.
While everyone should have working smoke detectors in their homes, a person with a smell disorder should also have a detector for natural gas or propane, lest a leak go undetected and result in an explosion.
Perishable foods should be dated and kept refrigerated, and discarded when they expire. It may be wise for a person with normal olfactory function to check these foods before someone with an impaired sense of smell eats them.
Make sure all cleaning and garden products are properly labeled and stored separately from foods.
When cooking or baking, check periodically to make sure nothing is burning, and set a timer to ring when the food will be done.
Since you can’t rely on a “sniff test,” be sure to bathe and launder clothes regularly. Use underarm deodorant, and go easy with cologne. Regularly check diapers for visual signs that a change is needed.
For more information, consult the Web site of the National Institute on Deafness and Other Communication Disorders at www.nidcd.nih.gov