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Review
. 2023 Jul 24:17:1200448.
doi: 10.3389/fnins.2023.1200448. eCollection 2023.

Overnight olfactory enrichment using an odorant diffuser improves memory and modifies the uncinate fasciculus in older adults

Cynthia C Woo  1 , Blake Miranda  1   2 , Mithra Sathishkumar  1   2 , Farideh Dehkordi-Vakil  3 , Michael A Yassa  1   2 , Michael Leon  1   2   4
Affiliations
Review

Overnight olfactory enrichment using an odorant diffuser improves memory and modifies the uncinate fasciculus in older adults

Cynthia C Woo et al. Front Neurosci. .

Abstract

Objective: Cognitive loss in older adults is a growing issue in our society, and there is a need to develop inexpensive, simple, effective in-home treatments. This study was conducted to explore the use of olfactory enrichment at night to improve cognitive ability in healthy older adults.

Methods: Male and female older adults (N = 43), age 60-85, were enrolled in the study and randomly assigned to an Olfactory Enriched or Control group. Individuals in the enriched group were exposed to 7 different odorants a week, one per night, for 2 h, using an odorant diffuser. Individuals in the control group had the same experience with de minimis amounts of odorant. Neuropsychological assessments and fMRI scans were administered at the beginning of the study and after 6 months.

Results: A statistically significant 226% improvement was observed in the enriched group compared to the control group on the Rey Auditory Verbal Learning Test and improved functioning was observed in the left uncinate fasciculus, as assessed by mean diffusivity.

Conclusion: Minimal olfactory enrichment administered at night produces improvements in both cognitive and neural functioning. Thus, olfactory enrichment may provide an effective and low-effort pathway to improved brain health.

Keywords: cognitive loss; environmental enrichment; fMRI; olfaction; olfactory training; uncinate fasciculus.

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Conflict of interest statement

ML and MY have received travel expenses and compensation following presentations at P&G. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Flow chart for subject participation. Bold font denotes subgroups that were included in the statistical analyses (Pre-Covid Finishers, for neuropsychological assessments; and MRI Finishers, for MRI analyses).
Figure 2
Figure 2
Mean difference between pre- and post-measurements for the Rey Auditory Verbal Learning Test (RAVLT – A5). Statistically significant difference between groups using an ANOVA with repeated measures (p = 0.02).
Figure 3
Figure 3
Shows the mean diffusivity difference between olfactory-enriched and control older adults. Statistically significant difference between groups using an ANOVA with repeated measures (p = 0.04). Error bars denote standard error of the mean (SEM).
See this image and copyright information in PMC

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