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Losing Your Sense of Smell? The Causes Might Surprise You

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If you’ve noticed that your sense of smell (aka olfaction) isn’t what it used to be, you’re not alone. For some 20 million Americans, the ability to detect everyday smells, from baking bread to burning wood, is slipping away…or even gone. 

Why this matters: Even though primary care physicians rarely ask patients about loss of smell, it can be an early red flag for certain chronic medical conditions.

A Multitasking Sense

Few people appreciate the multitude of daily functions tied to their sense of smell. This all-too-often neglected sense serves as…

A key to appetite. Smell is responsible for most of our sense of taste. People with a diminished sense of smell often have a poor appetite, remarking that food is tasteless or just doesn’t taste the same. While taste buds can distinguish basic levels of sweet, sour, bitter, salty and umami (a savory, earthy taste), smell also plays an important but often underappreciated role in our ability to taste foods. 

A harbinger of serious disorders. A diminished sense of smell is often an early symptom of Parkinson’s disease and Alzheimer’s disease. In fact, smell dysfunction is the most common early symptom reported by Parkinson’s patients even before they suffer motor-­related symptoms, such as tremors or walking difficulties. 

A Hard-to-Spot Deficiency

Because few primary care physicians test for smell problems, you need to be alert for any suspected loss of this sense. 

This can be challenging because the loss of smell that tends to occur with aging happens gradually, and most people with health problems don’t recognize that they have lost their sense of smell. For example, loss of smell is present in about 90% of people with Parkinson’s disease, but most don’t recognize that they have a problem.

Self-defense: Even if you only suspect a change, you should report this to your doctor. If there is no obvious reason for the loss of smell, such as a cold, allergies or nasal congestion, then smell testing is recommended. 

Smell Testing

A number of tests are available to assess one’s ability to smell. These range from simple three-item scratch-and-sniff screening tests…the 16-item Sniffin’ Sticks odor identification test that uses felt-tip pens to dispense odors…to longer tests, such as the 40-item University of Pennsylvania Smell Identification Test (UPSIT).* With the 15-minute UPSIT, you are asked to smell a series of odors (such as rose, pizza, cinnamon and mint) and identify each odor from a list of choices. 

The UPSIT, which can be ordered by physicians online for a nominal cost, helps doctors to determine both the absolute and relative (to one’s age and sex) degrees of smell loss.

Treatment Options

The first step in treatment is to identify the cause of the smell loss. Olfactory problems related to Parkinson’s disease or brain damage are generally believed to be irreversible, but early detection is helpful in planning medical treatment. 

There is strong evidence in a 2013 paper published in JAMA Otolaryngology–­Head & Neck Surgery that regular exercise can help to maintain the ability to smell in later life, much like it can help to avert or delay the onset of dementia. However, it is not known whether exercise can reverse such impairment once it is present.

If the loss is due to simple inflammation, including that caused by chronic sinusitis, then treatment with powerful anti-inflammatories (such as corticosteroids) may bring back some sense of smell. Oral steroids typically restore smell function within about a week. Continued topical therapy with steroid sprays or washes can, in some cases, maintain the restored function. If nasal polyps are to blame, surgical removal can be helpful.

Promising therapy: Some evidence shows that the antioxidant alpha-lipoic acid may help one regain the sense of smell in certain cases, such as long-­lasting dysfunction due to upper respiratory infections. The suggested dosage is ­400 mg to 600 mg daily.  

Important: Before trying alpha-lipoic acid, talk to your doctor. This supplement has been shown to lower blood sugar, so people with diabetes need to use caution. It could also interact with some medications, including antibiotics, anti-inflammatories, tranquilizers, heart medications and chemotherapy drugs. 

Another option: Small amounts of smell-restoring alpha-lipoic acid can be found in foods. Good sources: Organ meats (such as kidneys and liver)…spinach…and broccoli. 

Are You at Risk?

 There are dozens of possible causes for smell loss. Among the most common…

Aging. With age, the nerves that are involved in smell weaken, and odor-detecting membranes lining the nose become thin and dry. 

Smoking. Because it irritates nasal passages, smoking impairs one’s sense of smell. The good news is that normal smelling function can return in less than a year after quitting in light smokers and over the course of several years in heavy smokers—providing another reason to quit.

Air pollution. Research published in 2016 in Environmental Health Perspectives noted that the tiny particulates in polluted air enter the nose, cross through the olfactory bulb and actually enter the brain. There the stray microparticles, commonly found in diesel exhaust and air pollutants, can induce an inflammatory response that can lead to brain tissue damage, the development of Alzheimer’s-like pathology and a loss of smell.

Certain medications. More than 70 medications can affect one’s sense of smell. The list includes heart drugs, such as the cholesterol-lowering medication atorvastatin (Lipitor) and blood pressure drugs such as amlodipine (Norvasc) and enalapril (Vasotec), and some decongestant nasal sprays. Unfortunately, there is not much data indicating whether stopping such drugs will reverse smell loss.

Head injury. Even a relatively minor head injury, as might occur when one hits the back of the head on the pavement after slipping on ice, can permanently damage the delicate nerve connections to the brain that control your sense of smell. 

*Dr. Doty is president of Sensonics International, the manufacturer and distributor of the UPSIT.

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Source: Richard L. Doty, PhD, FAAN, director of the Smell and Taste Center and professor of psychology in otorhinolaryngology: head and neck surgery at the Perelman School of Medicine, University of Pennsylvania, Philadelphia. He is an internationally recognized expert on taste and smell dysfunction and author or editor of 11 books, including The Great Pheromone Myth and Smell and Taste Disorders. Date: May 1, 2019 Publication: Bottom Line Health
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