Vital Tips to Get Better at Maintenance of Brain Health at the Workplace. Part IV. Smell or Olfaction.
Evgenia Leonova, PhD, MBA
Life Sciences Executive, Entrepreneur, Lecturer, Speaker
Older people with smell loss have three times the likelihood of earlier death than their peers with no smell loss, leading to the suggestion that smell function is a sign of overall brain health,”- Dr. D.P. Devanand, et al
Smell deficits are associated with a number of medical conditions known to have viral underpinnings, including numerous cardiovascular, endocrine, immune, metabolic, and neurodegenerative diseases,” – Dr. R.L. Doty
In the animal kingdom olfaction is the main and the most important sense. By smell, animals find prey, a mate, and a safe place for rest. For humans, the importance of olfaction is often got overlooked. Usually, a sense of smell is considered to be poorly functioning in the human body, but still, it determines a lot of human behavior. We can get alerts by the smell of leaking natural gas, fire, spoiled food, and environmental toxins. We identify how clean the environment, clothes, etc are for us by the smell. We decide how nice a person is by smell as well.
How does the smell actually work?
Volatile Organic Compounds (VOC), which are small molecules with a high vapor pressure at room temperature and low solubility in water, travel with inhalation way through the human nasal airway and reach special receptors in the olfactory bulb. Those small molecules are usually a product of decomposition from the environment. By structure, they are aldehydes or esters that easily can be converted to the corresponding acids and alcohols Ref. 3.
The interesting fact about the molecules, VOCs, that a human can detect via smell is that the VOCs that humans exhale are considered to be a “human phenotype”,and currently used for detection of multiple diseases. The exhaling breath contains products of body metabolism and can identify a range of issues from cancer to gastroenteric problems. This method is called “breath biopsy.”
Getting back to the smell factory…
“Odorant-laden air must first traverse the upper airway, penetrate the narrow olfactory cleft, and absorb into a specialized mucus that covers the neuroepithelium in which the ciliated olfactory receptors are embedded,” – Dr. Doty
The mucus contains around 2500 proteins that are responsible for protection from viruses and bacteria, identification, and transfer of the VOCs to the smell receptors through the aqueous environment. Those proteins are antioxidants, growth factors, immune factors, peptides, antimicrobial and regulatory proteins etc.
In 2004 Buck and Axel from Howard Hughes Medical Institute (HHMI) won the Nobel Prize in Physiology or Medicine by shedding light on how the smell receptors actually work.
As it turned out the smell receptors are from the same family as visual receptors. This family of proteins is called G – proteins and this family of proteins has thousands of members Ref. 4.
“Half of all drugs work through G-protein receptors of a different type,” – Dr. Axel and Dr. Buck
After the VOCs got interacted with the G-receptors, the second messengers get released cAMP, which opens ion channels and generates an action potential that goes to the brain. There are several neurons that are responsible for the transfer of the impulses from the G-receptors to the brain: mitral cells, tufted relay neurons, granule cells, and periglomerular neurons.
The part of the brain that gets the impulses is called the olfactory cortex: entorhinal cortex, piriform cortex. This cortex is located in the periamygdaloid cortex. It covers the amygdala.
The most important thing about this part of the brain is that this region has a significant contribution to the processing of spatial information. The spatial information often refers to geospatial data or geographic information that connects location, people, and activities. Also, this brain’s region is responsible for the expression of the stored memory.
"Among viruses capable of entering the brain in animal models via the olfactory nerves or perineural spaces are the Japanese encephalitis virus, influenza A virus, herpesviruses, poliovirus, paramyxoviruses, vesicular stomatitis virus, rabies virus, parainfluenza virus, adenoviruses, West Nile virus, chikungunya virus, La Crosse virus, mouse hepatitis virus, and bunyaviruses" Ref. 5.
So we got to know that smell has the strongest connection to human memory. But the interesting fact is the memories associated with the smell are very individual. Moreover, Dr. Doty in his book claims that there is no such a thing as pheromones, everything is very individual. For example, in the study conducted by Dr. Blumenthal, it was shown that the smell of happiness and nostalgia is connected to childhood location and age. So, for the people who grew up on the East coast flowers were the most nostalgic odor; for the ones from South it was the smell of fresh air, in the Midwest it was farm animals, on the West coast it was meat barbequing odor.
“Differentiation of the odor- inducing nostalgia based on age demonstrated that those born from 1900-1930 were more likely to describe natural smells such as trees, hay, horses, pines, and meadows whereas those born from 1930-1980 were more likely to describe artificial smells that made them nostalgic for their childhood. These smells included Play-Doh, PEZ(R), SWEETARTS, Vicks VapoRub(R), and jet fuel,” – Ref. 6
RECOMMENDATIONS FOR YOUR WORKPLACE
VOCs often can NOT be consciously detectable by humans and dangerous in many senses. Some VOCs can cause headaches, can be a reason for cancer development and spread dangerous diseases.
The best thing you can do for yourself is to be sure the filters and your air conditioners are up to date and capable of catching VOCs. Also, a personal air purifier can help.
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The study, conducted by several scientists, shows that the olfactory sensory and brain work’ sharpness are interconnected and many doctors recommend improving your olfactory capabilities via training.
“MRI data analysis revealed that the classical OT leads to increases in cortical thickness/density of several brain regions, including the right superior and middle frontal gyrus, and bilateral cerebellums.
Both olfactory training methods can improve olfactory function and the improvement is associated with changes in the structure of olfactory processing areas of the brain,” – Ref. 7
Most people consider the smell of jasmine, citrus, and peppermint to be the most energizing and awakening. But for some, the smell of a new car or a book can have a better effect.
“Why do books smell, though, and why do we find the smell so intoxicating, bordering on the addictive?
"Bibliosmia or book-smell is caused by the chemical breakdown of compounds within the paper. What we’re smelling is the slow death of the book, albeit over a very long period of time (paper nevertheless endures for centuries, sometimes longer), which also explains why, as a general rule, the older the book, the better the smell. The paper contains cellulose and lignin (a polymer of aromatic alcohols which is also responsible for the pages of your old books turning yellow), although old books also contain a number of other chemicals, including benzaldehyde, vanillin, ethyl hexanaol, toluene, and ethyl benzene. As the name of vanillin suggests, the resultant bibliosmia is sweet in both a figurative and a most literal sense" - From to the Secret Library by Dr Oliver Tearle
Blog post for Healthy Happy HelpFul, by Dr. Evgenia Leonova
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