lavender, eucalyptus or rose
The researchers invited 43 people between the ages of 60 and 85 to participate in the study. None of them had cognitive impairment or dementia. 20 volunteers were given a diffuser and seven packets each containing a natural essential oil. The bottles smell of lavender, rose, orange, eucalyptus, lemon, mint, and rosemary. When the subjects went to bed, they put a different canister in the diffuser and one scent stayed in the air for two hours. The other 23 people who made up the control group also got an aroma diffuser and turned it on before going to bed, but their devices only released a subtle fragrance for a few minutes.
Half a year later, the volunteers sat down to do the tests. One of them was the Ray test, which is used to test memory. It consists in that the person being tested has to repeat 15 simple words that he heard a moment ago. Then he does the task five more times, but each time a different list of 15 words is read out. At the end of the test, the participant is asked to repeat the memorized words from the first list.
Just under ten years ago, scientists proved that humans can distinguish and remember a trillion odors.
It turned out that the volunteers whose bedrooms smelled nice not only slept more peacefully and slept better, but also achieved up to 226% more. Better scores on memory tests than those in the control group. The improvement in memory ability was also noted in the MRI brain scans. In these people, a brain region called the Hamat bundle, which connects the amygdala to the prefrontal cortex and is associated with memory, worked more efficiently. This study confirms the relationship between smell and memory, but more importantly, it suggests that smelling pleasant scents can stimulate the brain and protect against memory loss.
Smell can also help young people remember, as scientists from Northumbria University in Great Britain have shown. The researchers sprayed rosemary oil in a classroom and asked the students to take memory tests. The young men performed better and felt less tired than the volunteers who underwent the same tests but in an odorless room. For Dr. Alan Hirsch of the Smell and Taste Research and Therapy Foundation, who has been researching the sense of smell for years, there was nothing surprising about this. And his research shows that if we’re in a place that smells good – like violets or coffee – our brain works more efficiently and takes less time to learn a lot of material than when there’s no smell in the room.
Burnt and then coffee
It is not known whether aromatherapy, proposed by researchers at the University of California, would help people already diagnosed with cognitive loss, as well as those with other health problems. An inability to perceive smells can be an early sign not only of Alzheimer’s disease and dementia, but also of nearly 70 neurological and psychiatric diseases, including Parkinson’s disease, schizophrenia and alcoholism.
More than 40% of people suffer from smell disorders. People suffering from COVID-19. Patients experience olfactory hallucinations or incorrectly identify smell – when the smell of coffee is in the air, they smell burnt. They are also more sensitive to bad smells than good ones. They smell a fire, cigarette smoke, or burning rubber, but they don’t smell their favorite perfume or flowers. for the prof. This isn’t surprising, says Dr. Piotr Skrzyński, an otolaryngologist from the Institute of Hearing Physiology and Pathology. Our sense of smell serves, among other things, to protect us from danger. That is why we can easily and quickly detect odors associated with danger or bad mood – says the professor. Skrzynsky.
The difference between the perception of pleasant and unpleasant odors was demonstrated by scientists from the University of Tokyo, who recorded brain reactions using an EEG. Japanese scientists have shown that the brain detects the smell of rotten fruit and spoiled fat much faster than the smell of fruits and flowers. Information about an unpleasant odor in the environment appears in the conscious brain after 300 ms, and about a pleasant smell – only after 500 ms.
Sniff the chocolate
Smell has long been the least known human sense. He does not seem particularly affectionate or particularly demanding. Yes, it warns of danger: fire, rotten or burnt food and provides valuable information about the world around, but that’s all there is to it. For years, it was believed that humans could distinguish between only 10,000 odors. And just less than ten years ago, scientists from the Rockefeller University in New York proved that humans can distinguish and remember a trillion odors, which is 100 million times more than previously thought. So why not use our nose as efficiently as we can? Because our ancestors decided that sight and hearing would provide us with more information about the surrounding world, they began to develop these two senses. They helped them get food or find their way home.
However, we still have the ability to use our sense of smell, as the experiment of scientists from the University of California at Berkeley has shown. The researchers asked 32 students to wear blindfolds and earplugs on their ears and to use their sense of smell to find objects with different scents. At first, the young men do not cope well with the task, but after several attempts they start to find the hidden objects.
The same effect was achieved in the following experiment. The scientists blindfolded a group of people, blocked their ears, and placed special pillows on their hands, elbows and knees. The volunteers prepared in this way had to feel the smell of chocolate on the grass on all fours and, guided by this smell, overcome a 10-meter track. After several attempts, they were able to overcome the scent-marked path. They did it almost as well as dogs, although a dog’s nose is equipped with 220 million receptors that pick up odor molecules, while a human’s has only 5-20 million.
in fetal life
The concept of the human nose changed after 2004, when the Nobel Prize was awarded for such seemingly simple discoveries. It was picked up by Richard Axel of Columbia University in New York and Linda P. Buck of Cancer Research Center in Seattle, who showed that up to three percent of our genes are responsible for the formation of olfactory receptors on the surface of cells.
The Nobel laureates determined that all olfactory receptors have a similar structure, but differ in details, because each acts on different substances. Most odors are complex – the aromatic bouquet of substances acts on different olfactory cells with different intensities. We can recognize and remember the scent patterns created in this way.
It was also shown that the olfactory receptors begin to become active already in the 21st week of pregnancy. Thanks to them, the fetus learns to recognize the taste and smell of mother’s milk and itself. Therefore, immediately after birth, the newborn easily finds his way to his breast and, after a few days, unmistakably recognizes the smell of his own milk. This shows how important this sense is and that it is he, and not hearing or sight, that will most likely and quickly warn of danger.
Today, humans are known to have about 400 different types of specialized olfactory receptors in their noses. A single odor molecule can activate several different olfactory receptors, while a particular receptor can be activated by several different odor molecules. This comprehensive olfactory system enables us to recognize the presence, quality (whether it be the scent of cherries or smoke) and intensity of millions, perhaps even trillions, of different odors.
The road to obesity
The sense of smell not only informs us of dangers, but also evokes memories and adds flavor to dishes. Odorless food loses its flavor and can have a surprising effect on metabolism, scientists from Andrew Dillen’s team at the University of California, Berkeley, have shown. Scientists gave genetically engineered mice a toxin that temporarily blocks odor-sensing neurons. In this way, they suppressed the animals’ sense of smell. They then fed the rodents one group was given a normal diet and the other group was given fatty foods, the equivalent of cheesecake and pizza, which usually made them fat.
After more than three months of eating normal food, the odorless mice weighed slightly less than the mice whose sense of smell was intact. Surprisingly, the mice that were odorless and fed a high-fat diet lost more weight than the other groups. Their weight was 16 percent. Fewer than the mice that received the odors. The explanation for this difference seemed obvious: mice with a poor sense of smell ate less food because they didn’t like the food, but this turned out to be a mistake. All animals ate food with the same caloric content and did the same amount of exercise.
Other studies showed that mice that couldn’t smell stayed slimmer because they burned more calories. Dr. Dillin believes that when a mouse can’t smell food, it may feel like it’s eating more than it’s actually eating, causing it to expend more energy. According to the scientist, this study indicates that the sense of smell modifies the amount of energy that animals save and consume.
It is not known whether humans react the same way to loss of smell. Dr. Thomas Hamel of the Technical University of Dresden has serious doubts about this. For many years, he has studied people who were unable to detect odors due to head injuries or other reasons. Few of them lost weight.
