Has the smell of warm chocolate chip cookies ever transported you back to childhood? Or does the scent of roses remind you of your grandmother’s lotion? Indeed, our sense of smell plays a huge role in memory recall and knowing this, scientists wanted to know if it could be used intentionally to help improve memory in older adults.

In a small but promising new study of the effects of aromatherapy essential oils on memory in healthy adults ages 60 to 85, researchers determined that olfactory enrichment may provide a low-cost approach to reduce neurological impairment in older adults.

How did a study about scents get on the radar of neuroscientists?

Consider that past research has shown that cognitive decline is either accompanied by—or sometimes preceded by—loss of sense of smell in some of neurological disorders, including dementia, Alzheimer’s, and Parkinson’s. Factor in that previous research has suggested that exposing older adults to multiple scents or odorants can be beneficial to cognitive abilities.

The Research

A team of scientists from the University of California, Irvine, conducted a clinical study to see if a 6-month intervention of nightly aromatherapy could improve cognitive skills in older adults. All participants were assessed at baseline and again after the 6-month intervention using the following:

• tests of olfactory performance

• questionnaires on quality of life and depression

• fMRIs (functional magnetic resonance imaging) to check for changes in brain structural connectivity and changes in brain structures

• cognitive assessments (e.g., a pattern separation test to determine the ability to distinguish between two similar stimuli)

The 43 participants who were divided into two groups:

• The experimental group (20 participants), who were exposed to one different essential oil every night for a week for 2 hours using a diffuser

• The control group (23 participants), who were exposed to only trace amounts of odorants for the same amount of time

The seven scents, which were from The Essential Oil Company in Oregon, were: rose, orange, lemon, rosemary, lavender, peppermint, and eucalyptus.

It’s worth noting that due to the pandemic, many participants were unable or unwilling to return to the campus for cognitive assessments at the end of the intervention. This reduced the cognitive assessment dataset to 23 participants, of whom only 12 experienced olfactory enrichment. In addition, none of the volunteers had cognitive impairment.

The Results

 Of the 12 cognitive measures analyzed, one produced a significant difference: participants in the experimental group displayed a 226% improvement in their performance on the Rey Auditory Verbal Learning Test. The test, which includes word list recall, assesses verbal learning and memory.

In addition, the researchers observed improved functioning in the left uncinate fasciculus, which was assessed by the average water diffusion rate within brain tissue. The uncinate fasciculus is a brain pathway that deteriorates with both age and Alzheimer’s disease. It plays a crucial role in learning and memory.

Why would scent improve memory in some older adults?

“It was known that the loss of olfactory stimulation causes the memory centers of the brain to deteriorate,” explains Dr. Michael Leon, senior author on the study and professor emeritus of neurobiology and behavior at the University of California Irvine. “The olfactory sense is the only sense that has direct access to the memory centers of the brain and [aromatherapy] is a good way to stimulate those centers with little effort.”

The results of the study were published in the July 24, 2023 edition of the journal Frontiers in Neuroscience.

MBJ

Wendy Burt-Thomas writes about the brain, mental health and parenting.

Check out the original research:

https://www.frontiersin.org/articles/10.3389/fnins.2023.1200448/full