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Unlocking the Science and Impact of Our Sense of Smell

  • Audrey Bresar
    • The science of smell

    We don’t notice our sense of smell until something pungent or delightful permeates the air. It allows us to enjoy the fresh scent of cut flowers or plug our noses when a skunk wanders into the neighbourhood. 

    The science of smell is not just about fragrances. It is a powerful part of our general well-being and influences our emotions, memories, and health. 

    The Science Behind Smell 

    When we breath in, tiny particles called odour molecules enter our nose. These molecules attach themselves to special receptors that then send signals to the part of our brain called the olfactory bulb. Here, our brain says, “Hey, I smell something,” and can connect it to memory or feelings. 

    Studies have shown that smell influences human interaction, mood, and sexuality. Our olfactory system directly connects to the parts of the brain that process emotion and form memories. Scents trigger immediate reactions. A pleasant odour can stir up feelings of happiness, while foul-smelling scents can make you cringe. The emotions tied to scents can also evoke specific memories. Pheromones, while not a strong or identifiable scent, can trigger responses in the brain that influence sexual attraction.  

    Play Doh

    Have you ever smelled Play-Doh and been transported back to your grade 1 classroom? I bet that even at the mention of it, you were able to smell it, right? The intense emotion connected with the smell is so powerful that in 2018, Hasbro trademarked the scent.

    The olfactory system can detect and process over 1 trillion odours. Smell can affect emotional and physiological responses. When our noses detect cookies baking or smoke, signals travel from our nose to the olfactory bulb and then to the amygdala.

    The amygdala is the part of the brain that processes emotions, like fear or stress, which can trigger the release of cortisol. Calming or pleasant odours that make us happy release the “feel-good” chemicals in our brain, like dopamine and serotonin. 

    The role of smell is important to our well-being. It influences two key areas that contribute to our quality of life: nutrition and social behaviour.

    Nutrition – Smell influences our food choices. If something smells pleasant, we enjoy our food while steering clear of unpleasant-smelling food. The olfactory system also helps us determine if something is spoiled or dangerous to consume, which helps in avoiding illness. Not only does smell influence our food preferences, but it is also integral to taste.  Smell and taste create flavour perception that adds to the enjoyment of food. 

    Social Behaviour – An odour can evoke strong emotions and memories for you, good or bad, and this can influence your relationships and interactions with people. Scent also affects your mood, for example, lavender for calming and citrus for uplifting. In certain cultures, scent is used in ritual or ceremonial practice, such as frankincense, which attaches  meaning to a collective tradition. 

    Although our sense of smell is so exact and expansive, it is still weak compared to other animals.  Animals use scent to communicate, mark territory, ward off predators, attract prey, and show they are ready to mate. 

    Smell Disorders and Causes

    As one of the five senses, smell connects us to the world around us. Smell is crucial for taste, identifying harmful foods, and evoking memories and emotions. During the pandemic, loss of smell, or anosmia, was frequently reported as a symptom of COVID-19. Approximately  27% of Canadians still report a loss of sense of smell due to the illness. 

    However, there are other smell disorders, including:

    How Loss of Smell Affects Your Health

    Studies in older adults have shown that loss of smell can be related to higher levels of frailty, fatigue, and reduced physical activity and can be an early sign of broader health issues such as physical and cognitive decline.

    Loss of smell is often one of the first senses affected in conditions such as dementia and cardiovascular disease. Early detection of smell loss through screening can help identify individuals at higher risk and potentially slow down their physical and cognitive decline.  

    No matter how old you are or what level of loss you experience, the loss of smell can affect the quality of life. People suffering from anosmia can experience depression and isolation due to the disconnect between smell and emotion.

    Food choices and experience are affected. Meals may be less enjoyable, you may eat less, or you may ingest spoiled foods. Loss of smell can also impact your safety by not alerting you to hazardous chemicals, gas leaks, or fire. 

    Nose-Blindness

    We have all seen the television commercials for air fresheners to eliminate odours we can’t smell anymore. Olfactory fatigue, or nose-blindness, occurs when we are continually exposed to a specific smell and become less sensitive to it.

    For example, if you have pets or fry food, you may not smell the odours lingering in the air; however, if you go outside and come back in, you will smell those odours again. This is why we can’t smell our own bad breath. These familiar, habitual scents fade into the background, changing how we react to them.

    Scent Free Policies

    The adoption of scent-free workspaces is becoming more prevalent across the country. About 3% of Canadians suffer from a chronic condition called environmental sensitivity that detects scents at very low levels. Workplaces and organizations, like nursing homes and health care facilities, are creating policies that address sensitivity from exposure to scented products.

    It isn’t just perfume; these products can range from shampoo to deodorant to hand soap to cleaning products. People who suffer from environmental sensitivity can experience headaches, dizziness, nausea, and shortness of breath. 

    Restoring Smell with Innovation

    Since the pandemic, more research has been done to understand loss of smell and how science and technology can help. At the University of Western Ontario, a novel treatment is being studied on test participants to alleviate parosmia and anosmia.

    A stellate ganglion block is injected into the nerves at the base of the neck which alters the body’s sympathetic responses. One participant who had suffered from parosmia after contracting Covid-19 found relief within two weeks after the injection.

    Smell training is another tool to help with smell distortion. After suffering from loss of smell due to Covid-19, two Canadian entrepreneurs created Sniffly, a rehab program to help regain your sense of smell based off the 2009 research by Thomas Hummel. The cost of this virtual smell rehabilitation program is approx $10, and users can access lessons that guide you through the training. 

    An electronic nose system is used to help detect smells by simulating the way the olfactory system works. It uses sensors to identify and classify odours through machine learning. 

    Scientists are studying how stem cells can help restore the sense of smell by repairing damaged cells in the nose. This treatment could be helpful for people who have lost their sense of smell due to illnesses like Covid-19. 

    Another innovation to help with anosmia is a digital nose device that fits in the nostrils and uses electrical signals to create odours that people can sense. The technology can also detect smells from different directions, which we now do by sniffing and moving our heads around. 

    The Future of Smell

    Richard Costanzo [left] and Daniel Coelho [right] demonstrate the external components of their olfactory prosthetic. In a complete system, after the sensor detects an odor, the transmitter would send a signal to a stimulator implanted in the brain. Photo credit DeAudrea ‘Sha’ Aguado

    Scientists are working on a new bionic nose that uses sensors to pick up scents in the air. A stimulator implanted in the brain would receive the signals and recreate the experience of smelling. This could be a game-changer for people suffering from anosmia. 

    Digital smell creates, transmits, or simulates scents in digital formats. Although the technology is still in its early stages, it could be used in areas like entertainment, healthcare, and even advertising. Imagine if you could smell the cookies baking on screen when you are watching a movie, or smell the roses while in the middle of VR game, or smell that new car scent in an advertisement? Using odours in these applications creates a memorable experience that can potentially influence use and purchase decisions. 

    Odours bring the world around you to life. They unlock tucked-away memories, making us feel happy or sad. They alert us to danger and give us pleasure. They add complexity and depth to our days, from the fresh odour of coffee in the morning to the lingering scent of a candlelit bath.  

    Most times, treating the underlying condition will help with loss of smell, as with sinus infections or colds. Surgery may be required in instances where a blockage or deviated septum causes the loss. 

    Treatment

    If you are concerned about your sense of smell, visit a healthcare professional for a referral to an ENT who will conduct simple sniff and smell tests to determine any issues with smell. Further tests like an MRI or CT scan may be required. While covered by medicare, wait times to see an ENT can be anywhere from 3 to 12 months, and in some cases longer depending on where you live.

    Private options are available for those with the means or who have insurance that may cover some of the expenses. Note that you will have to leave your home province to seek out private care. For those who may be interested in this option, booking a consultation with a clinic will provide more information on services and cost of treatment based upon your situation. 

    Other options lie within the scope of medical tourism. According to the online magazine Medical Tourism, Canadians can find “high quality, low cost facilities” globally that provide the treatment they require. Platforms can connect you with ENTs around the world. 

    Tips to make your own smell training jars:

    Be patient and consistent. It may take some people longer than others to notice a difference. Your sense of smell is important and exploring avenues to treat any potential disorder is crucial to your overall well-being.

    “Nothing is more memorable than a smell. One scent can be unexpected, momentary and fleeting, yet conjure up a childhood summer beside a lake in the mountains; another, a moonlit beach; a third, a family dinner of pot roast and sweet potatoes during a myrtle-mad August in a Midwestern town. Smells detonate softly in our memory like poignant land mines hidden under the weedy mass of years. Hit a trip wire of smell and memories explode all at once. A complex vision leaps out of the undergrowth” 

    ~Diane Ackerman, poet and essayist

    ~Read more from The Health Insider~

    The information provided on TheHealthInsider.ca is for educational purposes only and does not substitute for professional medical advice. TheHealthInsider.ca advises consulting a medical professional or healthcare provider when seeking medical advice, diagnoses, or treatment.

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