Why do I smell like poop

Enigmatic phantom smells

Quirky perceptual disorder: some people smell odors that are not there. As has now been shown, such phantom smells occur more frequently than previously thought. One in 15 people aged 40 and over suffers from such an olfactory disorder, and in women between 40 and 60 it is even one in ten, as a US study reveals. What triggers these olfactory hallucinations is so far only partially known.

Imagine smelling the foul smell of burnt hair, feces, or old cigarette smoke - but no one else is noticing it. Because the smells so clearly and unpleasantly smelled by them are not even there. You are an olfactory hallucination, a sensation that only exists in your head. Doctors refer to this olfactory disorder as phantosmia or phantom odor.

"The perception of phantom odors can seriously affect those affected," explain Kathleen Bainbridge of the US National Institutes of Health in Maryland and her colleagues. Because the phantom smells usually contain unpleasant scents, those affected lose their appetite, for example, and they eat too little.

Causes mysterious

But how this olfactory disorder develops and how many people suffer from it is only partially known. “The causes are not yet understood. This disorder could be related to overactive olfactory cells in the nose, but also to a malfunction in the part of the brain that processes olfactory signals, ”explains Bainbridge. It only seems clear that such phantom smells occur mainly in older people.

To provide more clarity, Bainbridge and her team have now evaluated the data from 7,417 women and men aged 40 and over who participated in a national health study from 2011 to 2014. By including information about living conditions, health status and possible risk factors such as smoking, alcohol consumption or head injuries, they hoped to learn more about the triggers of phantosmia.

Especially common in middle-aged women

The result: a total of 6.5 percent of the participants suffered from phantom odors - roughly one in 15 people aged 40 and over. This rich disorder occurs particularly frequently among women: on average, they suffer from it twice as often as men, as the researchers report. But despite the often high level of suffering, apparently only very few of those affected talk about it: Only eleven percent of the participants had already turned to a doctor with their problem.

Also surprising: Contrary to previous assumptions, phantom odors do not simply become more common with increasing age. Instead, people between the ages of 40 and 60 are particularly likely to suffer from phantom odors, the study found. Among women, the proportion of those affected in this age group even reached ten percent. In the over-60s, it was only 7.5 percent, according to the scientists.

Environmental toxins or drug side effects?

But what had triggered these olfactory disorders in the participants? As the researchers found, the phantom odors were particularly common in connection with head injuries, but also generally in poor health. People from lower income groups were also affected 60 percent more often than rich people. Also noticeable: The phantosmias were particularly often associated with a persistently dry mouth.

According to the scientists, this indicates that phantom odors occur not only as a result of head trauma, but also as a result of the chronic influences of certain environmental toxins. For example, poorer people in particular could be exposed to more toxic substances in their surroundings or at work. “The association with poor general health and persistently dry mouth could also point to a drug side effect as a possible cause, said Bainbridge and her colleagues.

In the search for the causes of this puzzling perception disorder, a lot of manhunt is necessary, as the researchers emphasize. The first step, however, is to look for conspicuous clusters of cases, as they have done. "From here, other scientists can come up with ideas about where to look for possible causes," says Bainbridge. (JAMA Otolaryngology-Head and Neck Surgery, 2018; doi: 10.1001 / jamaoto.2018.1446)

(NIH / National Institute on Deafness and Other Communication Disorders, 08/17/2018 - NPO)

17th August 2018