The scent of fresh coffee or warm, home-baked bread – wonderful! The breeze of salt and sun in the sea air – great summer feeling! Smells, fragrances and flavors accompany us throughout our lives. Our sense of smell develops in the womb before all other senses. An infant can recognize its mother by the familiar smell just three hours after birth. And 90 percent of mothers are able to identify their baby by its scent after an hour. But our nose can do even more. Science has only recently started to focus on how decisively it shapes moods and behavior. dr Rachel Herz, odor expert at Brown University in Rhode Island, USA, explains exciting findings from olfactory research. The fact that many essential oils have a healing effect has been adequately documented by studies. But smells can toocause disease ? In the case of toxic and allergenic substances, this is not a question. But what about everyday smells?
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effect of bad smells
»BAD SMELL CAN CAUSE DISCOMFORT«
A number of odor-induced health problems without medically visible signs are summarized under the collective term “multiple chemical intolerance syndrome” (MCS). Those affected complain of a wide variety of symptoms such as exhaustion, headache, dizziness, body aches, tachycardia or shortness of breath. “Everyday scents that others perceive as positive, such as fruit aromas or perfume, are cited as triggers,” says Dr. Heart.
Whether MCS is a real disease is controversial. One thing is certain: from a medical point of view, MCS patients are physically healthy. Since around 75 percent of those affected also suffer from psychological problems such as anxiety disorders, a psychological explanation suggests itself. But what about the remaining 25 percent? In her testing laboratory, Dr. heart, how strongly scents are linked to positive and, above all, negative experiences. Their result: “A smell can trigger the same emotions as the original situation.” So there is much to suggest that the smells themselves do not cause illness. They only initiate a learned chain of reactions.
Moments when our nose reacts particularly sensitively
WONDER WORLD OF SMELLING
- Humans can perceive more than 10,000 different scents. Olfactory cells inside the nose, the roof of the nose, absorb tiny scent components from the air. Corresponding signals are sent to the brain via nerve tracts.
- The brain areas in the limbic system that process smells and feelings are closely connected. That’s why the interactions are so strong. Smells activate the amygdala, our emotional center in the brain. Imaging methods were able to show this.
- With special examination methods, the ENT doctor can check the sense of smell and taste. Under certain circumstances, the brain waves are measured during various olfactory stimuli. In some cases, x-rays of the sinus, CT scans of the skull, and neurological tests can help with the diagnosis.
- BOOK TIP: Rachel Herz: “Because I can smell you”, Herbig, 268 pages, 19.95 euros
Basically, men and women can smell equally well. But a woman’s ability to smell fluctuates during the menstrual cycle. The sense of smell is particularly well developed around the time of ovulation, “because then it is important to choose the biologically best possible partner,” explains the biologist and psychologist. Studies by the University of Bern have shown that women prefer the smell of men who have an immune system that is as different as possible from theirs. This offers the offspring the best possible chance of surviving diseases and environmental pollution unscathed. So what we think of as magical attraction or love at first sight is at least also a matter of body chemistry. Characterized by the archaic program to ensure the survival of the species – and guided by our incorruptible sense of smell.
Olfactory disorders and their consequences
»SOME DISEASES ARE ASSOCIATED WITH A LOSS OF SMELLING«
A smell test for diagnosis? Precisely this approach could possibly help in the future to identify and treat degenerative diseases of the nervous system such as Alzheimer’s or Parkinson’s at an early stage. This is before typical symptoms such as memory loss or motor disorders appear. Studies have shown that in up to 80 percent of those affected, the sense of smell is impaired in the early stages. A study by Chicago’s Rush University came to the conclusion that the stronger the olfactory impairment, the more pronounced the later brain changes. Olfactory disorders caused by respiratory infections, allergy-related inflammations in the nasal cavity, polyps or a deviated nasal septum can also reduce the ability to smell. Only when the cause has been eliminated – for example by medication or an operation – scents are perceived more intensively again. Cortisone, which has a decongestant and anti-inflammatory effect, often helps. In some cases, an impairment remains. Then, under certain circumstances, olfactory training can help: the olfactory cells can develop new nerve fibers through the targeted perception of certain scents.
The situation is completely different for migraine patients, who react particularly sensitively to odors shortly before and during an attack. Here, sensory perception returns to normal quickly after the seizure. It becomes difficult in the case of sports or traffic accidents: If nerve pathways important for the sense of smell are damaged as a result of a skull injury, the sense of smell may not be able to be restored.
Other triggers for olfactory disorders can be diabetes, high blood pressure, hypothyroidism, but also some medications. According to current estimates, around 5 percent of the population suffer from a loss of the sense of smell (medical: anosmia), which is not caused by a chronic disease of the nose.
Relationship between the sense of smell and the psyche
»SMELLING DISORDERS CAN INVOLVE MENTAL PROBLEMS«
The inability to smell the environment, to perceive familiar people and situations through their scent, often has a massive impact on the quality of life of those affected. dr Herz speaks of a “negative domino effect on the healthy functions of the emotional system”. If the amygdala (see box on the left) is not stimulated by the olfactory cells, its functionality suffers. It can even shrink. It is not uncommon for depression to be the result, which should be treated medically. Because the typical symptoms of lack of drive to sleep and concentration disorders to suicidal thoughts usually increase without therapy. Conversely, the emotional world also influences our nose. Studies have shown that severely depressed people are often unable to perceive fragrances in normal concentrations.
»IF THE SENSE OF SMELL DECREASES, THE WEIGHT OFTEN CHANGES AS WELL«
“Food flavors stimulate the appetite,” says Dr. Heart. Because taste and smell are inextricably linked. If the sense of smell is lost, the feeling for normal food quantities and intervals often also disappears. If you can’t smell what you’re eating, everything feels bland. And those who can no longer enjoy meals often automatically eat less. In addition, food flavorings can no longer fulfill their function as a memory aid – according to the motto “Attention, it’s time to eat something again!”. This problem arises for many older people when, from the age of 65, the sense of smell and taste decreases more and more. But there are also people who shovel food indiscriminately when their nose and tongue no longer give feedback.
