OLFACTION AND BRAIN HEALTH

By Ana Elena Sastrias, Certified Natural Perfumer and Aromatherapist

Can You Train Your Brain Through Your Nose?
For the last 7 years there has been much more scientific interest in recognising the importance of the sense of smell or “Olfaction” in our lives as well as in applying the Olfaction Training methodology for reversing several conditions like “anosmia”, the loss of the sense of smell. The partial or total loss of sense of smell can be due to injury or infection creating an olfactory dysfunction.
The Olfactory Neural System is complex and is able to replace olfactory dead cells with new olfactory cells from the Olfactory Bulb to the Cerebral Cortex and the Limbic System every few months.
Olfaction Training also has been proven to boost brain health, activating brain regions
that govern emotion and memory, bypassing the Thalamus. This training of the sense of smell assists in the increment of grey matter in the Hippocampus and the Orbitofrontal Cortex, by using short, daily sessions of intentional scent exposure to protect the brain from the risk of cognitive decline in ageing populations.

New generations, influenced from the social effects from the COVID-19 and post viral
controls, have experienced a life intimately linked to computers and screens constantly.  They spend more time secluded in offices or home watching screens browsing social media on their phones, than experiencing real sensory reality, like going to the bush, a park, a garden, re-connecting with Nature, and relating physically with people and animals. This generation requires attention, as some of them already suffer “anosmia” and have not been appropriately treated for this condition.

What could be the effects of not having Olfactive stimulation?

• Loss of Sense of Smell: Not being able to detect something that can be poisonous or dangerous, so our sense of safety and alarm warning does not get activated.
• Not able to enjoy pleasant smells and flavours in the food. Feeling depressed.
• Food tastes different or bland.
• Not be able to relate well with other people or not be able to feel what other people feel (meaning, lack of empathy), having low or unbalanced moods.
• Loss of Cognitive Capabilities: Without a proper Olfaction Training, Verbal capabilities deteriorate.  As the Scent Smell training works on Memory, Semantic and Verbal fluency, this can activate some neural connections related to those areas.

There have been Olfaction Training studies on patients with Parkinson’s and Alzheimer’s diseases bringing some measurable improvements in Olfactory, Memory and Cognition areas.
So, there are still people suffering from an Olfactory Dysfunction that do not consider
the effects of losing the sense od smell partially or totally important and take it for granted as an irrelevant sense compared to Vision or Hearing. All senses are important, but the Sense of Smell, Olfaction, since the last century has been completely culturally erased from the senses’ priority list not knowing that indeed Olfaction is an important and primary sense.

When we were born, before we could see and recognise visually, we smelled and tasted.
We related through the sense of smell to our mother even when being in our mother’s womb. We used our taste buds to recognise the taste of our mother’s milk.
Having previous Olfactory experiences can open a door to re-training our brain and re-
connecting with our memory and olfactory sensors in our brain and body, so we can compare what was in our memory of that smell, how we actually smell, and what associated feeling or emotion we had. We need to activate neural connections through a routine of Olfaction Training.
Some other people are fearful about Scents or Aromas in public spaces, cosmetics like
creams and soaps, candles, diffusers and the use of detergents as they have been exposed to allergens experiencing skin irritation, asthma attacks, dermatitis or psoriasis, rhinitis or sinusitis. It is true that there is a population affected by the environment. In these cases, it is recommended to only use the Scents of Nature going to to these places. This will also be true regarding the scent of foods.
Avoiding synthetic and strong concentrated fragrances in the environment will be key for the detoxification process as well as having proper ventilation.

Key Health Benefits and Neuroplasticity​
When smelling scents, it is recommended to smell Nature, Food, and Essential Oils as they are in Nature, since we have the advantage of smelling the healing properties of Scent molecules.
Our brains have the ability to continuously change in response to the experience, called “Neuroplasticity”, and this ability may be key to the way in which smell training works.
Neuroplasticity involves the generation of new and/or strengthened connections
between neurons (brain cells), which may in turn lead to changes in thinking skills or
behaviours. We can see evidence of Neuroplasticity when we practice a skill like playing an instrument or learning a new language.
The olfactory network in our brains is particularly neuroplastic. When we frequently use the many parts of the brain involved in the process of smelling through repeated exposure to odours, this process may lead to increased olfactory abilities and cognition. It’s possible then that we could ‘train the brain through the nose.’

Another important factor that is not widely discussed is having a good, healthy diet.
What we ingest, can alter our digestive system and our sense of smell. It has been recently acknowledged in science that there are olfactory sensors in our digestive system. These sensors send signal information to our brain. It is now recognised that certain cases of Anxiety and Depression and other sensitivities have origins coming from problems in our Digestive System. Taste is related to Smell.
The Vagus Nerve is the longest cranial nerve in the body and is intimately linked in the
regulation of our gut, cardiovascular system, respiratory and endocrine systems.

So, what does the Vagus Nerve have to do with our sense of smell and taste?
The Hypothalamus and the Vagus Nerve communicate in a highway exchange fashion
between the gut where the vagus nerve entangles its way through, and the brain that provides feedback. When the distension of the gastric wall changes during the intake of food, the sensitivity of olfactory neurons changes to induce and almost repulse food odors in order to signify that we are satisfied and do not require more. This is fascinating!!

Most recent studies are starting to integrate AI and collection of data from databases to enable personalised treatment for Olfactory Dysfunction.
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The International Perfume Foundation provides an in-depth Olfaction Training Certification Course on re-training our Sense of Smell.  This course is not just for people interested in Natural Perfumery and Aromatherapy, but also for those interested in improving their own or other people’s health.

REFERENCES:
1. Dr. Wolf - Anna & Bahar-Fuchs, Alex - “HEALTH & MEDICINE - How smelling can help
your brain” - 14 March 2019 https://pursuit.unimelb.edu.au/articles/how-smelling-can-help-your-brain.
2. Nazareth, Lynn - “CSIRO - You can train your nose - and 4 other surprising facts about your sense of smell” - 23 January, 2025 https://www.csiro.au/en/news/all/articles/2025/january/train-your-nose
3. Liu, Xialei , Yin, Junjei et al - “ The potential of Olfactory Training and dietary interventions in the treatment of Olfactory Dysfunction: A review” - Trends in Food Science and Technology - Volume 167 - January 2026 https://www.sciencedirect.com/science/article/abs/pii/S0924224425005965
4. ATP, Science - “Olfactory - The First Steps of Digestion” July 30, 2020 https://
atpscience.com.au/blogs/blog/olfactory-the-first-steps-of-digestion
5. Matiashova, Lolita; Hoogkamer,Anouk Lisa; Timper,Katharina - “ The Role of Olfactory
System in Obesity and Metabolism in Humans” Metabolites 2024, 25 December 2023