How Scent Affects Our Mental Health

By Dr. Will Cole

Have you ever had a smell take you instantly back to a single memory? The smell of fresh cut grass in the summer acts as a reminder of the seemingly endless summer days spent playing in the backyard as a kid. The smell of freshly baked chocolate chip cookies sends you right back to grandma’s kitchen. Or the smell of tires evokes memories of trips to the auto shop with your dad on a random weekend.

Scents have long been tied to memories and feelings of nostalgia. Even the great novelist Marcel Proost famously wrote about it when describing how his biscuit and tea transported him back to a childhood memory. Because of this, odor-evoked memory is now often referred to as the “Proust phenomenon”.

And when it comes to food specifically, these fond-memories can even play a role in why you crave certain foods. Studies have shown that memories triggered by odors evoke more of an emotional response than memories provoked by other stimuli such as sight or sound. In my functional medicine telehealth clinic, I often see this emotional tie to these “comfort” foods as a reason why people have trouble adopting healthier eating habits and giving up foods that they know exhausterbate their chronic health problems.

The Psychophysical Connection

The olfactory bulb is responsible for how we process smells. This structure in the front area of our brain sends information to the other areas of our body for further processing. Smells are directly sent to the amygdala region of the brain responsible for processing emotional experiences and the hippocampus region of the brain responsible for associative learning. 

And even the act of eating further perpetuates the scent-emotion phenomenon. When you eat, the food molecules drift up into your nasal passage making a lot of what you experience as “taste” is also how your brain interprets it’s smell. Interestingly enough, that’s why you can hold your breath and pinch your nose and it diminishes the flavor of whatever you are eating. When you look at our other senses, none of them have the same connection with these specific areas of the brain as smell does.

It makes sense though considering the fact that our sense of smell is the first and only developed sense we have while growing in the womb and is one of our strongest senses in childhood. Therefore, seeing how closely smell and emotions are tied physically, no wonder why we develop such strong emotional ties around smells and flavors since childhood is when we are creating our foundational memories that we build our whole perception of life around.

The Health Benefits of Odor-Evoked Memory

Taking into account that scent is linked to associative learning, we can see the physiological benefits of indulging in aromatherapy.

1. Stress reduction

Studies have found that those who smelled scents that were associated with a positive memory or calming event experienced a slowing of breath and reduced stress, similar to what is seen in meditation.

2. Reduced inflammation

Odors associated with positive memories were also linked to reduced inflammation. One study compared levels of TNF-a - an inflammatory signaling protein - after smelling a scent associated with a good memory and after smelling a neutral scent. Researchers found that the levels of TNF-a were significantly lower after being exposed to the emotional-associated scent.

3. Curbed cravings

Interestingly enough, just how certain smells can trigger emotional cravings, certain scents can also curb cravings. While this has less to do with odor-evoked memory, studies have shown that specific essential oils - grapefruit in particular - can help reduce cravings. This can be seen through its ability to activate sympathetic nerve activity to facilitate lipolysis which can inhibit weight gain.

So, next time you catch a whiff of a nostalgic scent, breathe it in and take advantage of it's stress-reducing benefits!