Phantom Smells Affect More Noses Than You Think
About 6 percent of Americans detect bad smells that aren't actually there.
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Have you ever thought you smelled something awful and distinct, like burning rubber or spoiled milk, only to realize that actually, there's nothing there? If so, you and your misleading nose are not alone. About 6 percent of Americans over age 40 experience mysterious "phantom" odors, a new study suggests.

Phantom odor perception has been observed in medical clinics, but it wasn't clear how common this condition was, said lead study author Kathleen Bainbridge, an epidemiologist at the National Institute on Deafness and Other Communication Disorders (NIDCD), part of the National Institutes of Health (NIH). [Photos: Stinky 'Corpse Flower' Blooms]

To answer that question, the researchers turned to the National Health and Nutrition Examination Survey (NHANES), a national survey on the health of Americans. The surveys conducted between 2011 and 2014 contained a single question about odor perception: "Do you sometimes smell an unpleasant, bad, or burning odor when nothing is there?"

The survey results, from more than 7,300 participants ages 40 or older, led the study authors to estimate that 6.5 percent of American adults in that age group perceive phantom odors. About two-thirds of the people with deceptive noses were women, and the trait was more common among people who described their health as fair to poor, compared with those who said they were in good health. Other factors that were associated with increased frequency of phantom odors were persistent dry mouth and a history of serious head injury.

Bainbridge told Live Science that what surprised her and her colleagues was that the rates of phantom odors decreased among participants over 60 years old, from 6.5 percent in younger participants to 5.4 percent in the older participants.

The researchers compared their results to a similar study of Swedish adults between ages 60 and 90, published last year in the journal Chemical Senses, which found that just 4.9 percent of participants experienced phantom odors. But like the NHANES study, the Swedish study also found that the trait was more common in women.

Scientists don't yet understand the root cause of a misleading schnoz. "The condition could be related to overactive odor sensing cells in the nasal cavity or perhaps a malfunction in the part of the brain that understands odor signals," Bainbridge said in a statement.

Only 11 percent of the people who experienced phantom odors said they had ever discussed them with a clinician — evidence that the sense of smell is often overlooked, despite its importance. Smells "can have a big impact on appetite, food preferences, and the ability to smell danger signals such as a fire, gas leaks, and spoiled food," Judith Cooper, acting director of NIDCD, said in the statement.

The researchers weren't able to assess how health conditions such as seizures, migraine headaches or mental illness may affect the ability of people to accurately perceive smells, but they hope to do this in future studies.

The results from this part of the NHANES study were published today (Aug. 16) in the journal JAMA Otolaryngology-Head & Neck Surgery.

Original article on Live Science.