Ellie Knox (Author) and Alice Xu (Mentor)

Have you ever wondered why certain smells can trigger a rush of memories from the past? Imagine someone walking into the room wearing a floral perfume, suddenly bringing back memories of an old friend who favored the same scent. The structure of our brains explains the link between smell and cognition that can give rise to these recollections. Unlike other sensory systems that route information through the thalamus to be processed before the information reaches the corresponding cortical areas, scent signals are sent directly to the olfactory bulb, efficiently cutting out the middleman. The olfactory structure is in close contact with the amygdala and hippocampus, which are critical brain areas for memory and learning (Mouly & Sullivan, 2010). This neural pathway explains why scents can sometimes trigger memories more vividly than some other types of sensory information, forming the basis for aromatherapy, which harnesses the power of scents, usually through periodic diffusion and inhalation of essential oils, to improve memory and other cognitive functions.

Remembering is Right Under Your Nose

Memory is one of the most valuable facets of the human mind. Essential to retaining learned information, it allows us to hold details about everything that matters in our lives, even trivial things like where we left our keys. Considering memory’s pivotal role in our day-to-day function, it is no wonder that strategies to improve memory are highly coveted. Amazingly enough, the solution to improve recall may lie within our own senses. Research shows that smell can enhance memory (Filiptsova et al., 2017; Moss et al., 2017).

In one study, participants were tasked with two memory assessments, one asking them to reconstruct images they had previously seen and another requiring them to recall two-digit numbers. The group tested in a room diffused with rosemary oil performed better in both tasks than those working in the absence of the essence (Filiptsova et al., 2017). The difference in performance indicates a heightened ability to remember visual images and numbers due to aromatic treatment. 

These effects might be especially useful in educational settings. Another study separated schoolchildren ages nine to eleven into two rooms—one room sprayed with rosemary essential oils and the other unscented. Children were given five memory tasks, including remembering a list of ordered words, a list of numbers, the last word in each sentence in a set of sentences, the amount of dots counted on multiple pages, and, at the end, the words from the first game. The students in the aromatherapy room obtained significantly better memory results in three out of five tasks (Moss et al., 2017). Clearly, memory retrieval is improved when facilitated by the use of smell.

Smarter with Smell

Can smell be a secret weapon in boosting cognitive abilities? Research suggests it could be. Not only has aromatherapy been found to improve memory capacity, but it has also been shown to enhance other brain functions. Cognition is crucial to long-term health and healthy aging (Morley et al., 2015), underscoring the importance of sharpening mental skills to maintain quality of life. Aromatherapy has demonstrated significant effects on our mental acuity, attention, and alertness, making it a valuable tool in both everyday life and clinical settings. 

In a study involving math calculations, participants showed faster response times when exposed to lavender and rosemary aromas. Lavender specifically improved accuracy, while rosemary raised both self-evaluated alertness and brain waves that indicate heightened alertness (Diego et al., 2009). These findings, showing significant improvements in mathematical ability and alertness, demonstrate enhanced performance on mental tasks as a result of the inhalation of fragrances.

Aromatherapy’s value to the brain extends far past solving math problems. Stimulating the olfactory sense with lavender oil has been shown to affect even higher-order cognitive abilities, such as attentional shift and cognitive flexibility. Study participants aged twenty-two to forty-two wore EEG caps, which measure brain activity, and performed the task-switching paradigm: a set of functions that evaluate an individual’s competency when both switching between different tasks (think answering an email in the midst of doing homework problems, but much more complicated), and completing different tasks that are mixed together. Executing these functions involves perceiving visual input, modifying mental strategies for tasks requiring different approaches, changing selective attention, and managing issues that arise, all while attempting to minimize the lapse in efficiency that occurs when adjusting to perform unassociated tasks. After completion, participants took five large breaths of lavender oil and repeated the paradigm. Following this intervention, they reacted faster and with greater precision. Frontal lobe EEG waves linked to clear-mindedness, relaxation, and quick thinking increased. In contrast, waves linked to subconscious thinking decreased (Afghan et al., 2024), showing heightened awareness and greater presence of mind following the whiffs of the oil. The shocking findings concerning the performance of such a complex procedure, including an increased ability to manage mental loads, switch between concepts, and direct attention, exemplify the augmentation of high-order cognitive processes due to aromatherapy.

Aromatic Intervention for Neurological Disorders

The onset of neurological disorders occurs in conjunction with the loss of the sense of smell; intriguingly, this sensory loss can predict Alzheimer’s effects (Tian et al., 2022). The observation of this association has led researchers to hypothesize that stimulating the olfactory areas of the brain could potentially rehabilitate the cognitive decline involved in these conditions. The hypothesis has been supported by multiple studies regarding memory and cognitive function in those suffering from neurological disorders.

In one such study, assessments measuring cognitive dysfunction were administered to elderly patients with vascular dementia and Alzheimer’s before and after a twenty-eight-day period of aromatherapy. During this time, patients were exposed to rosemary and lemon essential oil in the mornings and lavender and orange during the evenings. These tests concluded a greater level of cognitive function, comprehension of concepts, and abstract reasoning following the exposure to the oil aromas (Jimbo et al., 2010).

Moreover, olfactory-related cognitive improvements are not limited to dementia patients. Another study evaluated individuals with Multiple Sclerosis based on their accuracy in recognizing whether or not a sentence is semantically sound, as in it makes logical sense, and their memory of those sentences. Those exposed to lavender essential oil achieved considerably higher scores on the cognitive test than their counterparts subjected to the placebo (Mohammed Rezaie et al., 2021). Therapeutic use of lavender scent improved the patients’ working memory and mental acuity in discerning the validity of the sentences.

Such discoveries unveil the potential for aromatherapy to not only delay the onset of neurological disorders but also to improve cognitive functions in those already affected by such conditions. Future long-term studies could illuminate just how valuable aromatherapy might be in rehabilitating individuals with neurological disorders.

Making Scents of It All

For most of us, our sense of smell is one tool that isn’t used nearly enough to activate the areas responsible for memory and learning and to maximize our brain health. With this evidence, hopefully, you are convinced of the power of aromatherapy in fortifying your own brain power. However, before implementing aromatherapy into your routine to reap the cognitive rewards, it is wise to ensure you are well-informed on methods of safe use. Essential oils should always be inhaled in a well-ventilated room. To be cautious, avoid directly inhaling the essential oils for over fifteen minutes. Instead, use a diffuser to implement aromatherapy. Diffusion should be done in a periodic schedule, alternating from diffusing for thirty minutes to one hour, taking a break for thirty minutes to one hour, and so on. The body becomes less responsive to the essential oils after continuous exposure, therefore, the interval method ensures both safety and efficient use (Tisserand Institute, 2015-2024). Next time you need to boost your memory while studying for an important exam, or even want to be extra alert the morning of a big presentation, consider putting a few drops of lavender oil into a diffuser or burning a rosemary candle. You might be impressed by the mental benefits!

References

Afghan, R., Heysieattalab, S., Zangbar, H., Ebrahimi-Kalan, A., Jafari-Koshi, T., Samadzadehaghdam, N. (2024) Lavender Essential Oil Inhalation Improves Attentional Shifting and Accuracy: Evidence from Dynamic Changes of Cognitive Flexibility and Power Spectral Density of Electroencephalogram Signals. Journal of Medical Signals & Sensors, 14(4), 12. journals.lww.com/jmss/fulltext/2024/04180/lavender_essential_oil_inhalation_improves.3.aspx.

Diego, M., Jones, N., Field, T., Hernandez-reif, M., Schanberg, S., Kuhn, C., Galamaga, M., McAdam, V., & Galamaga, R. (2009). Aromatherapy Positively Affects Mood, Eeg Patterns of Alertness and Math Computations. International Journal of Neuroscience, 96(3-4), 217-224. www.tandfonline.com/doi/abs/10.3109/00207459808986469.

Filiptsova, O.V., Gazzavi-Rogozina, L.V., Timoshyna, I.A., Naboka, O.I., Dyomina, Te.V., & Ochkur, A.V. (2018). The essential oil of rosemary and its effect on the human image and numerical short-term memory. Egyptian Journal of Basic and Applied Sciences, 4(2), 107-111. www.sciencedirect.com/science/article/pii/S2314808X16301890.

Jimbo, D., Kimura, Y., Taniguchi, M., Inoue, M., & Urakami, K. (2010). Effect of aromatherapy on patients with Alzheimer’s disease. Psychogeriatrics: The Official Journal of the Japanese Psychogeriatric Society, 9(4), 173-179. onlinelibrary.wiley.com/doi/full/10.1111/j.1479-8301.2009.00299.x.

Mohammed Rezaie, S., Shahabinejad, M., Loripoor, M., & Reza Sayadi, A. (2021). The effect of aromatherapy with lavender essential oil on the working memory of women with multiple sclerosis. Journal of Medicine and Life, 14(6), 776-781. www.ncbi.nlm.nih.gov/pmc/articles/PMC8811666/.

Morley, John, et al. (2015). Brain Health: The Importance of Recognizing Cognitive Impairment: An IAGG Consensus Conference. Journal of the American Medical Directors Association, 16(9), 731-739. www.sciencedirect.com/science/article/pii/S1525861015004387?via%3Dihub. 

Moss, M., Earl, V., & Heffernan, T. (2017). Any Sense in Classroom Scents? Aroma of Rosemary Essential Oil Significantly Improves Cognition in Young School Children. Northumbria University Research Link, 7(4), 450-463.  nrl.northumbria.ac.uk/id/eprint/32447/.

Mouly, A., & Sullivan, R. (2010). Memory and Plasticity in the Olfactory System: From Infancy to Adulthood. The Neurobiology of Olfaction, Chapter 15. www.ncbi.nlm.nih.gov/books/NBK55967/.

Tian, Q., Bilgel, M., Moghekar, A., Ferrucci, L., Resnick, S. (2022). Olfaction, Cognitive Impairment, and PET Biomarkers in Community-Dwelling Older Adults. Journal of Alzheimer’s Disease, 86(3), 1275-1285. pubmed.ncbi.nlm.nih.gov/35180111/.

Tisserand Institute. (2015-2024). How to Use Essential Oils Safely. Tisserand Institute. tisserandinstitute.org/safety-guidelines/.