What’s That Smell?

Endless days in pajamas. Replaying board games that previously collected dust. Predominantly only speaking to family in your home. Who wouldn’t expect loneliness, boredom, anxiety, depression, and anger? At least that’s what the American Psychological Association states are potential outcomes without our typical access to fulfilling activities, socialization, and a normal volume of sensory stimuli. Despite states entering phase II, our normal day full of both good and bad smells is not yet normal.

Smell has been proven to evoke memories through a complicated neuroanatomical connection. The person smells freshly cut grass and although some would say it’s not as pleasant as ripe, freshly cut strawberries, it can instantly transport an adult to their 7 year old summer of running through sprinklers, eating popsicles, and laughing with friends. A rush of happiness ensues reducing stress and lowering systemic inflammation. It’s fulfilling to have an arsenal of happy memories that are triggered by sudden identification of scents. Imagine walking down the street about to enter your office building to deliver a critical presentation that could shape your career and you’re hit by the smell of sizzling hot dogs and exploding popcorn. Instantly you are taken back to the baseball game that you enjoyed yesterday. A smile falls across your face, you inhale deeply, and notice your muscles relax. You’re happy and ready to take on your presentation.

Whether big like humans or small like one cell organisms, both are drawn towards or repelled by smells. Chemotaxis, or the ability of a one cell organism to move away from or towards a substance depicts the earliest importance of identifying smells to avoid harm or find food. Studies have demonstrated that movement of the organism can be experimentally repeated indicating that even a one celled organism requires a connection between smell and memory for survival. This has persisted as a necessary trait throughout evolution.

Humans have evolved to be a bit more complex. Olfactory learning occurs during all major life events and again has been shown to be essential for survival. What if you couldn’t identify that spoiled milk in your fridge? The unpleasant bathroom effect could occur again if humans were unable to learn from the experience. Scientists have developed an animal model for olfactory research to ascertain the nuances of emotional learning with well defined experiments that continue to support the theory that smell is tightly linked with emotions and subsequently happiness. This can be applied theoretically to how the human brain functions.

In our current state of physical distancing and debated mask wear, have we reduced the malleability of our brains because we are missing out on a typical day full of pleasant and malodorous stimuli? Will returning to a new normal feel difficult or impossible? And what is it like for someone who cannot smell?

Anosmia, or loss of sense of smell, can be life altering. Kathy Smith*, a retired realtor and grandmother who suffers from anosmia states “I used to be awed by my grandchildren’s intoxicating infant smell that provided me so much happiness. I can no longer enjoy this”. Her life is impacted daily. “I do exercises to help me remember the smells that I knew so well. I can feel the coolness of ice cream and see that it’s vanilla. In my mind, I can evoke the smell from my memory, but I do feel I am missing a huge part of what my life used to be.”

If You Don’t Use It, Do You Lose It? 

This is true for sensory input related to touch. A complicated neurologic syndrome called Complex Regional Pain Syndrome is theorized to occur when a limb is immobilized in response to an injury. The neurological pathways change to respond to all touch signaling the brain that even gentle stimuli evokes pain. How crazy is that? It’s real and quite a challenge to treat.

Surprisingly, studies performed on individuals with nasal obstruction due to congestion have shown an increase in odor sensitivity once olfaction is fully restored. Do you too miss the smell of your beloved relatives’ home, a particular dessert from a favorite restaurant that has remained closed, and maybe even the inside of an airplane that will whisk you away to your premier destination? Each smell is tied to a memory that elicits emotion. Emotions that we all want to experience. Will these emotions be further heightened when the smell that links to that memory is again identified? In the meantime, we could all buy the game, WooWee What’s That Smell, to keep up with stimuli and ultimately, happiness.

What about those individuals who are experiencing a temporary loss of smell as a symptom of COVID-19 while remaining mostly at home?

Sally Wilson*, a city dweller in her 30s and property marketing specialist temporarily lost her sense of smell after attending a conference in March. At the time she was unable to be tested to confirm infection with COVID-19. “I didn’t realize I had lost my sense of smell until it came back”, she states. “One day, all of the sudden it was like I could smell and taste my cooking again. It was intense. I then wanted more curbside takeout.”

Smell, memory, and happiness are intertwined and enhance our lives. There’s hope that we can eventually return to the HD version of living, but what’s to come when we finally come out of the first surge? Will it quickly be followed by a second surge and subsequent return to reduced stimuli? We can only wait and smell. 

References:

Complex Regional Pain Syndrome Fact Sheet. (n.d.). Retrieved from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Complex-Regional-Pain-Syndrome-Fact-Sheet

Gotfried, JA and Wilson, D.A. (2011). Smell In Gotfried, JA (Ed), Neurobiology of Sensation and Reward (p.102-15). Boca Raton, FL: CRC Press/Taylor & Francis.

Herz, R. (2016). The Role of Odor-Evoked Memory in Psychological and Physiological Health. Brain Sciences, 6(1), 22. 

Mouly, A.M. (2010). Memory and Plasticity in the Olfactory System: From Infancy to Adulthood In Menini, A. (Ed), The Neurobiology of Olfaction (p. 204-214). Boca Raton, FL: CRC Press/Taylor & Francis. 

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