Smells Of Home

by Zoe Gemmel

Strange, isn’t it? How the simplest scent can stop us in our tracks and send us spiralling back in time to a forgotten or cherished place of our past; the welcoming aroma of freshly baked cookies; the combined fragrance of the salty ocean breeze with the richness of melting ice cream; the lingering scent of mildew and nicotine clinging to the curtains and wallpaper. Our sense of smell is invariably linked to our memories, much like our senses of sight, sound, and taste.

This linkage goes far beyond flowery metaphors and instinctual feelings, however, as there is a very real science behind it. When, say, smelling a daffodil, the chemicals responsible for said smell are drawn up through the nostrils and dissolved in the mucus lining the nasal cavity. This step is crucial, as once dissolved, these chemicals are detected by olfactory receptor neurons. Essentially, these neurons are scouts, tasked with gathering information on smell and sending it to the olfactory bulb for identification.

Located just above the nasal cavity is an incredibly complex, five-layer structure called the olfactory bulb. Despite its rather small size (only measuring an average of 3mm) this section of the forebrain has direct connections to two points of interest within the brain to allow smells to influence emotions and memory more efficiently. The first point of interest being the Amygdala, which is often referred to as the brain’s emotional centre; primarily tasked with handling emotions, processing memory, making decisions, and co-ordinating fight-or-flight responses. The Amygdala closely gauges the environment sur- rounding us by receiving inputs from our sensory organs and other areas of the brain itself- which includes our second point of interest; the Hippocampus. This section of the brain is incredibly im- portant as it handles both long- and short-term memory, alongside spatial awareness, and learning.

Anosmia (noun) : The condition of having no sense of smell or being unable to smell certain things.

However, due to such a powerful linkage being forged between the nose and brain, it can often be trou- bling when this connection is severed. Losing the perception of smell (a condition known formally as “Anosmia”) can and does negatively impact our memory. Numerous groups from a variety of institutions have been conducting research into the phenomenon and have shown that a loss of smell is linked to a decreased recall in memory. Often, Anosmia is an impermanent condition, caused by inflammation or blockages within the nasal cavity. Interestingly, this condition has received notable media coverage as of late, as the most common symptom of COVID-19 is a sudden decrease in taste/smell perception.

The sudden onset of Anosmia can be a troubling sign, spe- cifically in older patients, as the loss of smell has been identified as a developmental indicator of both Alzheimer’s Disease and Parkinson’s Disease. With Alzheimer’s Disease in particular, the perception of smell (alongside oth- er tactile senses) deteriorates as the disease progresses.

But where the loss of the connection is a troubling sign of a weakening memory, that same link can be used to strengthen a mind as well. Aromatherapy is an excellent supplementary treatment, acting as a viable option in easing the symp- toms of “Behavioural and Psychological Symptoms of Dementia” (BPSD) for patients in later stages. Scents such as Laven- der and Lemon Balm are commonly utilised in soothing the aggression and confusion commonplace within these stages.