Olfactory Training: How Smell Shapes Memory and the Brain

The relationship between olfaction and memory is one of the deepest neurobiological connections in the human body. It is not just about identifying a pleasant or unpleasant aroma; the olfactory system has a direct anatomical link to the brain’s emotion and memory centers, such as the amygdala and the hippocampus.

This unique architecture explains why olfaction plays an essential role in cognitive health, impacting everything from the evocation of complex memories to the modulation of our well-being. Olfactory Training (OT) thus emerges as a structured tool to enhance this connection, with significant implications for the brain’s ability to adapt, known as neuroplasticity.

Olfaction as a Sentinel for Mental Health

The depth of this connection is clinically relevant. Longitudinal studies show that severe olfactory dysfunction (anosmia) is one of the earliest symptoms of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s. This sign can manifest years before motor or memory deficits.

Neuroimaging research provides the basis for this link: patients with olfactory dysfunction show greater atrophy in regions critical for memory. Furthermore, pathological markers of Alzheimer’s (such as tau and Aß protein aggregates) are often found early in the olfactory bulb.

The good news is that the olfactory system can be an ally in treatment. Research indicates that interventions focused on the olfactory mucosa can help attenuate cognitive decline and reduce neuroinflammation.

The Mechanics of Olfactory Memory

Olfaction acts as a powerful contextual trigger. The simple act of smelling a scent can evoke vivid and emotionally charged autobiographical memories—a phenomenon known as the “Proust Phenomenon.”

This occurs because the brain does not process odors in isolation; it perceives them synthetically, creating “odor objects.” A smell, like that of coffee, is a cognitive construct learned through the association between molecules and a source. Olfactory training is based on structured exposure to these odors to stimulate neuroplasticity.

How Does Olfactory Training Modify the Brain?

The benefits of training are linked to two key processes: neuroplasticity and adult neurogenesis.

The olfactory bulb is one of the few regions of the adult brain where new neurons are continuously generated. Olfactory training acts as a modulator of this plasticity. Repeated exposure to a specific odor selectively accelerates the birth of sensory neurons that respond to that smell. Furthermore, learning not only replaces cells but increases the density of “connection points” (dendritic spines) between neurons, strengthening communication between the nose and the cerebral cortex.

Olfactory Training for Everyone

Olfactory training is beneficial in different contexts. In patients with post-infectious olfactory dysfunction, training has been shown to induce lasting effects.

For healthy individuals, training acts as a cognitive exercise. The difficulty in naming odors is a known limitation of human cognition, and training challenges this ability. Professionals like perfumers and sommeliers, who practice verbalizing odors, strengthen semantic neural networks, consolidating the practice as a complete brain exercise.

September and Alzheimer’s Awareness

September is the month dedicated to Alzheimer’s awareness. Research on olfaction is not limited to early diagnosis; it is at the frontier of therapeutics. Recent discoveries show that olfactory receptors are also found in the brain and may be involved in the pathophysiology of neurodegeneration.

Therefore, Grupo Boticário, through the Olfaction Research Center (Centro de Pesquisa do Olfato), reinforces its commitment to cognitive health by annually supporting the event “Awakening Society to Brain Health,” promoted by the Supera Institute.

The 6th edition of the event, which was free and hybrid, was recorded and is available for those who wish to discover how to cultivate a lifestyle beneficial to the brain.

Watch the full recording at the link: 

Box: Practice at Home

3 Olfactory Stimulation Exercises

For those who want to start stimulating their brain through olfaction, we have separated three simple exercises based on scientific protocols that can be performed at home.

1. The Classic Protocol (Discrimination Training)

This is the most widely used method in research for rehabilitation and cognitive stimulation.

• What you need: 4 vials containing essential oils or natural items with distinct smells. The classic combination is: Rose (floral), Eucalyptus (resinous), Lemon (fruity), and Clove (spicy).
• How to do it: Twice a day (morning and night), smell each vial for approximately 20 seconds.
• The secret: While inhaling, try to mentally visualize the object that produces that smell. Mindfulness is fundamental to activating neural pathways.

2. The Guessing Test (Cognitive Challenge)

This exercise increases the cognitive load, forcing the brain to search for information in memory without visual aid.

• What you need: Ask someone for help or use opaque/blindfolded vials containing items from your kitchen (coffee, cinnamon, vanilla, mint) or even your favorite perfumes.
• How to do it: Shuffle the vials and try to identify the smell without looking at the contents.
• Variation: Try to rate the smell’s intensity on a scale of 1 to 10. This forces the brain to process the odor analytically.

3. Olfactory Mindfulness

This exercise integrates olfaction into the daily routine, combating the habitual inattention to smells caused by routine.

• How to do it: Choose three moments in your day to focus exclusively on the smell of your environment, ignoring sight and sound for a few seconds.
  • Example 1: When you wake up, smell your pillow or the morning air.
  • Example 2: During your shower, focus on the smell of the soap or shampoo, trying to mentally describe its notes (is it sweet? citrusy? woody?).
  • Example 3: Before eating, dedicate 15 seconds just to smelling the aroma of the food before the first bite.

Bibliographic References:

Doty RL. Odors as cognitive constructs: History of odor classification and attempts to map odor percepts to physical and chemical parameters. Chem Senses. 2025. DOI: 10.1093/chemse/bjaf022.

Hossain K, Smith M, Rufenacht KE, O’Rourke R, Santoro SW. In mice, discrete odors can selectively promote the neurogenesis of sensory neuron subtypes that they stimulate. eLife. 2025 ;13:RP96152. DOI: 10.7554/eLife.96152.

Keusters E, Clijsters M, Vansteelandt K, Van Gerven L, Bouckaert F. The influence of olfactory training on depressive symptoms and olfactory function in patients with olfactory dysfunction – A prospective observational pilot study. J Affect Disord Rep. 2025 ;20:100887 . DOI: 10.1016/j.jadr.2025.100887.

Franco R, Garrigós C, Lillo J. The olfactory trail of neurodegenerative diseases. Cells. 2024 ;13(7):615. DOI: 10.3390/cells13070615.

Gillmeister A, Pieniak M, Hummel T. Investigating plasticity of the olfactory system through the lens of specific anosmia. Cortex. 2025 ;192:53-63. DOI: 10.1016/j.cortex.2025.08.012.

Li Z, Li SB, Tan S, Liu LL, Yan C, Zou LQ. Neural correlates of olfactory working memory in the human brain. Neuroimage. 2025 ;306:121005 . DOI: 10.1016/j.neuroimage.2025.121005.

Naffaa MM. Neurogenesis dynamics in the olfactory bulb: deciphering circuitry organization, function, and adaptive plasticity. Neural Regen Res. 2025 ;20(6):1565-81. DOI: 10.4103/NRR.NRR-D-24-00312.

Hu X, Ma YN, Peng J, Wang Z, Liang Y, Xia Y. Exosomes derived from olfactory mucosa mesenchymal stem cells attenuate cognitive impairment in a mouse model of Alzheimer’s disease. Biosci Trends. 2025. DOI: 10.5582/bst.2025.01065.

Kawabata K, Bagarinao E, Seppi K, Poewe W. Longitudinal brain changes in Parkinson’s disease with severe olfactory deficit. Parkinsonism Relat Disord. 2024 ;122:106072. DOI: 10.1016/j.parkreldis.2024.106072.

Pützer A, Wolf OT. Odours as context cues of emotional memories – The role of semantic relatedness. Acta Psychol (Amst). 2021 ;219:103377. DOI: 10.1016/j.actpsy.2021.103377.