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. 2024 Mar;34(1):155-191.
doi: 10.1007/s11065-022-09573-0. Epub 2023 Feb 2.

Does Olfactory Training Improve Brain Function and Cognition? A Systematic Review

David E Vance  1 , Victor A Del Bene  2 , Vidyulata Kamath  3 , Jennifer Sandson Frank  4 , Rebecca Billings  5 , Do-Yeon Cho  6 , Jun Y Byun  4 , Alexandra Jacob  7 , Joseph N Anderson  8 , Kristina Visscher  9 , Kristen Triebel  8 , Karli M Martin  8 , Wei Li  10 , Frank Puga  4 , Pariya L Fazeli  4
Affiliations

Does Olfactory Training Improve Brain Function and Cognition? A Systematic Review

David E Vance et al. Neuropsychol Rev. 2024 Mar.

Abstract

Olfactory training (OT), or smell training,consists of repeated exposure to odorants over time with the intended neuroplastic effect of improving or remediating olfactory functioning. Declines in olfaction parallel declines in cognition in various pathological conditions and aging. Research suggests a dynamic neural connection exists between olfaction and cognition. Thus, if OT can improve olfaction, could OT also improve cognition and support brain function? To answer this question, we conducted a systematic review of the literature to determine whether there is evidence that OT translates to improved cognition or altered brain morphology and connectivity that supports cognition. Across three databases (MEDLINE, Scopus, & Embase), 18 articles were identified in this systematic review. Overall, the reviewed studies provided emerging evidence that OT is associated with improved global cognition, and in particular, verbal fluency and verbal learning/memory. OT is also associated with increases in the volume/size of olfactory-related brain regions, including the olfactory bulb and hippocampus, and altered functional connectivity. Interestingly, these positive effects were not limited to patients with smell loss (i.e., hyposmia & anosmia) but normosmic (i.e., normal ability to smell) participants benefitted as well. Implications for practice and research are provided.

Keywords: Aroma; Neuroplasticity; Odorant; Olfaction; Olfactory bulb; Smell training.

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Conflict of interest statement

The authors report no real or perceived vested interest that relate to this article that could be construed as a conflict of interest.

Figures

Fig. 1
Fig. 1
Overview of olfactory training and olfactory system connections
Fig. 2
Fig. 2
PRISMA diagram demonstrating screening method for literature search
See this image and copyright information in PMC

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