Alzheimer's / Dementia

8/28/2023 | By Steven Marshall

The link between smell and memory goes beyond the occasional nostalgic whiff! Research has demonstrated that smell therapy can minimize memory loss in older adults.

Have you found yourself recalling fond memories when you are exposed to a certain smell? Perhaps when you encounter the smell of a pie baking, you recall your grandmother’s kitchen, waiting for her to finish the delicious treat. While the link between smell and memory seems merely quirky, there may be a meaningful way to utilize the connection. Researchers are exploring the potential of smell therapy, also called olfactory training, to improve learning and memory – and to minimize memory loss and dementia in older adults.

Why is this link so strong?

The sense of smell is only one or two connections away from the areas of the brain responsible for cognition and emotion. In comparison, hearing and sight are several connections away from these brain areas. Because of its faster route, the sense of smell has a more significant impact on memory than our other senses.

How important is smell?

Our society seems to prefer odor-free environments, but that may be harming us as we age. Research shows that exposure to smell is an important factor in cognitive functions like memory and learning.

During the COVID-19 pandemic, approximately 15 million people lost their sense of smell, from a few months to possibly permanently. For these people, the olfactory areas of the brain, responsible for the sense of smell, show evidence of degeneration. It is believed that this degeneration could result in cases of “post-COVID dementia.”

What studies have shown so far

Sensory stimulation testing and intensive olfactory training (IOT) are two methods used to study the impact of smell on our cognitive abilities.

lighted turquoise aromatherapy diffuser. Image by Altitudevs. Article on smell therapy  and intensive olfactory training (IOT) for dementia prevention and treatment.

Researchers note that several neurological conditions are associated with the loss of smell. These conditions include Alzheimer’s, Parkinson’s, schizophrenia, and depression. Several factors contribute to the damage of our sense of smell, including smoking, head injury, menopause, and even chronic nasal congestion. In previous studies, this damage to the sense of smell has been linked to memory loss. In addition, the brain pathway known as the left uncinate fasciculus, which plays a role in memory encoding and retrieval, weakens with age.

A study published in the January 2022 issue of Geriatrics & Gerontology International Journal explains the impact of IOT. A group of 34 patients with dementia were exposed to 40 odors twice a day for 15 days. Results were compared to a separate group of 31 patients with dementia that did not complete IOT. Both groups of patients completed olfactory testing, depression screening, and detailed cognitive function tests. Researchers compared the tests completed before and after the 15-day study. Results showed an improvement in depression, attention levels, and memory functions in the group that completed the IOT. The researchers concluded that there was potential for IOT as a non-drug-based solution to treat dementia symptoms.

More recent studies have examined the effects of exposure to various smells during sleep. The sense of smell, unlike sound or touch, are less likely to awaken us from sleep, because sound and touch are routed through the brain’s thalamus, which is connected to sleep, while smell does not follow this path.

A study published July 24, 2023, in the Frontiers of Neuroscience, explored sensory stimulation in older adults. A group of 43 people aged 60 to 85 were divided into two groups. One group was provided with a diffuser and seven regular-strength essential oils, one odor each night of the week. The other group was provided with seven solutions with insignificant amounts of essential oils that would be difficult for the user to detect. Users continued the odor rotation for six months. Researchers completed word-list recall and other short-term memory tasks before and after the six months. Upon examination of the data, there was a notable 226% increase in results for the group that received the regular-strength essential oils compared to the results for the other group. These results show that olfactory enrichment, or smell stimulation, may improve brain health.

Moving forward

With the 226% improvement in cognitive function following smell therapy, researchers recommend adding olfactory stimulation to your daily routine.

To bring the potential impact of smell therapy to the general public, one group of researchers has formed the company Memory Air. They are creating a diffuser capable of providing the user with up to 40 different smells each night.

In the meantime, soak up the smells around you – or provide your older loved ones with plenty of pleasant odors. Since aromatherapy using essential oils offers a wealth of benefits, you can’t go wrong.

Related: The positive effects of sensory stimulation for Alzheimer’s patients

Steven Marshall

Dr. Steven Marshall, DNP, MSN, BSN, RN is a freelance health and medical writer with over 35 years of health care experience. He has worked in clinical and leadership roles throughout settings, including critical care, emergency care, air and ground transport, inpatient rehabilitation, oncology, infectious disease, ambulatory care clinics, and infusion therapy. He founded See Doc Nurse Write in 2023 to provide content sharing his clinical knowledge and experience across larger audiences.