RESEARCH

Overnight Olfactory Enrichment Using an Odorant Diffuser Improves Memory and Modifies the Uncinate Fasciculus in Older Adults

The study found that the group who received the real smells showed a statistically significant 226% greater improvement on a verbal learning and memory test called the Rey Auditory Verbal Learning Test compared to the control group. Additionally, the enriched group showed improved functioning in the left uncinate fasciculus, as measured by a change in mean diffusivity on the fMRI scans (p = 0.043).

Program Types: Therapeutic

Population Groups: Older Adults/Seniors, Dementia/Traumatic & Acquired Brain Injuries

Setting or Context: Homes/Private Residences

Health and Wellness Outcomes: Improved Cognitive Function, Longevity & Aging Well, Improved Quality of Life

Allied Profession Intersections: Occupational Therapy

Type of Activity: Sensory Stimulation

Evidence Type: Peer-Reviewed Studies, Randomized Controlled Trials, Quantitative Research

Measurement and Evaluation: Patient-Reported Outcomes, Standardized Assessment Tools, Longitudinal Studies

Access: Free

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Summary

This study wanted to see if using pleasant smells at night could help older adults’ memory and brain function. Researchers enrolled 43 healthy older adults between 60 and 85 years old. These participants were randomly divided into two groups: one group received real smells (olfactory enriched group), and the other group received very small, almost unnoticeable amounts of odor (control group). For six months, the enriched group used a diffuser that released one of seven different pleasant smells (like rose, orange, eucalyptus, etc.) for two hours each night when they went to sleep. The control group used the same diffuser but with bottles containing mostly distilled water with a tiny bit of odor.

Before and after the six-month period, all participants took memory and thinking tests. They also had brain scans using fMRI to look at changes in their brain structure. The researchers specifically looked at a brain pathway called the uncinate fasciculus, which is important for memory and tends to deteriorate with age. They compared the changes in test scores and brain scans between the two groups to see if the nightly smells had any effect. The study took steps to make sure participants followed the instructions, like weighing the odorant bottles and contacting them monthly.

Link

Woo, C., Miranda, B., Sathishkumar, M. et al. (2023). Overnight olfactory enrichment using an odorant diffuser improves memory and modifies the uncinate fasciculus in older adults. Front. Neurosci., 17

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