A new study published in JAMA Otolaryngology-Head and Neck Surgery finds that 1 in 15 Americans over age of 40 detect strange odours like burning hair or rotting food when nothing is there in real. The study is the first in the US to estimate how common the phenomenon is in nationally representative data. Phantom odour 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.

To answer the question, researchers used data from a survey conducted on participants over 40 years of age in 2011 to 2014 from National Health and Nutrition Examination Survey. The survey conducted on more than 7,300 participants contained a single question about odour perception: ‘Do you sometimes smell an unpleasant, bad or burning odour when nothing is there?’ The survey results led the study authors to estimate that 6.5% of American adults in that age group perceive phantom odours. The trait was more common among people who described their health as fair to poor. Other factors that were associated with increased frequency of phantom odours were persistent dry mouth and a history of serious head injury, as reported by Live Science.

Scientists don’t understand the root cause of a misleading schnoz. “The condition could be related to overactive odour sensing cells in the nasal cavity or perhaps a malfunction in the part of the brain that understands odour signals,” Bainbridge said in a statement. Only 11% of the people who experienced phantom odours said they had ever discussed them with a clinician. 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,” said Judith Cooper, acting director of NIDCD said in a statement.

The researchers couldn’t assess how health conditions such as seizures, migraine headaches or mental illness may affect the ability of people to accurately perceive smells. Millions of Americans experience some type of olfactory problem such as anosmia (inability to smell), hyposmia (decreased ability to smell) and parosmia (distorted perception of smell). Many people with smelling disorders also have issues with taste, because smell and taste are inextricably linked.

(The above story first appeared on LatestLY on Aug 22, 2018 11:21 AM IST. For more news and updates on politics, world, sports, entertainment and lifestyle, log on to our website latestly.com).