Enigmatic phantom smells

Unpleasant smelling disorders affect more people than expected

It stinks without any smell being there: Phantom smells are still a riotous disturbance of perception. filistimlyanin / iStock
Read out

Quirky Perception Disorder: Some people smell odors that are not there. As it turns out, such phantom smells are more common than previously thought. In the over-40s, every 15th person suffers from such an olfactory disorder, in females between 40 and 60 years, it is even one in ten, as a US study revealed. What triggers these olfactory hallucinations, however, is only partially known.

Imagine you smell the foul smell of burnt hair, feces or old cigarette smoke - but no one else perceives it. Because the fragrances that are so clearly and unpleasantly smelled are not there at all. They are an olfactory hallucination, a sensation that only exists in your head. Doctors refer to this smell disorder as phantosmia or phantom smell.

"The perception of phantom smells can seriously affect sufferers, " said Kathleen Bainbridge of the US National Institutes of Health in Maryland and her colleagues. Because the phantom smells usually include unpleasant odor notes, the sufferer, for example, loses their appetite and they eat too little.

Causes puzzling

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

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

Especially common in middle-aged women

The result: Overall, 6.5 percent of the participants suffered from phantom smells - roughly equivalent to every 15th person over the age of 40. This disorder is particularly common among women: they suffer on average twice as often as men, as the researchers report. But despite the often high level of suffering, apparently only very few people are talking about it: Only eleven percent of the participants had already turned to a doctor with their problem.

Surprising, too: Contrary to previous assumptions, phantom smells do not just become more common with increasing age. Instead, middle-aged people between the ages of 40 and 60 are more likely to suffer from phantom scurf, the study found. For women, the proportion of those affected in this age group even reached ten percent. For the over-60s, however, it was only 7.5 percent, the researchers say.

Environmental toxins or drug side effect?

But what had triggered these olfactory disturbances among the participants? The researchers found that phantom smells were particularly associated with head injuries, but also a generally poor state of health. People from lower income groups were also 60 percent more affected than rich. Noticeable too: Especially often the phantosmia went along with a persistent dry mouth.

According to the scientists, this suggests that phantom smells not only occur as a result of head trauma, but also through chronic effects of certain environmental toxins. For example, older people may be exposed to more toxic substances in their environment or at work. "However, the association with poorer general health and persistent dry mouth may also indicate a drug side effect as a possible cause, Bainbridge and her colleagues say.

In the search for the causes of this mysterious disturbance of perception is therefore still a lot of search needed, as the researchers emphasize. The first step, however, is to look for conspicuous heaps of fells as they did. "From here, other scientists can come up with ideas on 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, Aug. 17, 2018 - NPO)