Why do I smell 1

Suddenly it smells so strange. Somehow burned or spoiled. Or are these chemicals that exude this odor? That is quite irritating, because a cause of the unpleasant smell cannot be found at all. And people around you don't smell anything - it stinks a lot here. Should one really only imagine this stink?

The phenomenon of olfactory hallucinations is not that extraordinary. Around one in every fifteen adults repeatedly takes smells and smells for which no cause can be found even after a meticulous search for sources and which must therefore be regarded as non-existent. With the help of a large nationwide survey, doctors from the USA have now attempted to characterize the extent and forms of these phantom odors. In the trade magazine JAMA Otolaryngology - Head & Neck Surgery present your results.

Kathleen Bainbridge's team from the National Institutes of Health in the USA (NIH) analyzed data from more than 7,400 adults over the age of 40. It was found that 6.5 percent of the participants occasionally perceive phantom smells. Women complained much more often about the non-existent odors than men; in the current study, they made up more than two thirds of those affected. Apparently it is particularly bad between the ages of 40 and 60. During this phase, around ten percent of women occasionally experience the unpleasant sensations, men of this age group are less familiar with the phenomenon half as often.

Those affected can at least comfort themselves with the fact that the wrong smell perceptions subside with increasing age. Over the age of 60, only 7.5 percent of women have anything to do with it, from 70 onwards only 5.5 percent. The fact that olfactory sensitivity and olfactory hallucinations decrease with age has to do with the gradual loss of olfactory nerves, their declining function and a generally reduced sensory perception.

"Problems with the sense of smell are often overlooked, even though they are so important," says Judith Cooper, who researches sensory disorders at the NIH. "They can affect appetite and food preferences, as well as impairing the ability to perceive danger signals such as the smell of fire, gas, or rotten food."

The exact reason for olfactory hallucinations, as the phantom smells are also called, is still unclear. Presumably, the nerves that transmit odors to the brain are easy to irritate or send false signals. Sometimes they are also disturbed or damaged. This fits in with the fact that phantom smells occur more frequently after cranial brain injuries, unconsciousness or chronic inflammations in the head area. "It could also be due to overactive sensory cells in the nasal cavity - or a malfunction in the region of the brain where the nerve signals are processed," says Bainbridge. "In a first step we tried to describe the phenomenon on a larger database." Previous analyzes have been limited to individual case reports or limited age groups.

The ability of some people to perceive their senses in a coupled manner probably also has to do with overexcitation of the corresponding brain centers. So-called synaesthetes perceive sounds as colors or tastes as shapes. "The taste of my food does not have enough points, it is rather spherical," a person affected is said to have said in a famous case. For others, the sound of the shower sounds "yellow" and a rain shower sounds "green-brown" or letters are always colored in their minds and take up a position in the room.

It is still uncertain whether overexcitability or simply misdirected signals trigger the olfactory hallucinations. The fact that and why women generally react more sensitively to smells and therefore smell phantom smells more often is not only a concern of long-standing partnerships, but also of science. "Women are better at naming smells and are more bothered by the smells around them," write David Hsu and Jeffrey Suh of the University of California at Los Angeles in an accompanying comment: "In addition to their greater sensitivity to smells, there is their lower threshold to complain about unpleasant smells. " When men even notice exhausting scents, they seem to be more stoic about it than asking for fresh air or a deodorant.

No wonder that particularly odor-sensitive men like Frank Slade played by Al Pacino in "The Scent of Women" or Jean-Baptiste Grenouille in Patrick Süskind's novel "Parfum" exert a great fascination - especially when they are like the two novel- and film heroes have no or a beguiling smell of their own.

Phantom smells, on the other hand, are seldom described as seductive, but typically as unpleasant and characterized using terms such as "lazy", "rotten" or "chemical". "Patients who perceive particularly strong phantom odors often have a poor quality of life, their food is spoiled and they cannot maintain a healthy weight," warns Donald Leopold, olfactory researcher from the University of Vermont.