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Updated: Aug 23, 2025

A Free-breathing fMRI Method to Study Human Olfactory Function
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Olfactory identification ability in patients with mild cognitive impairment and Alzheimer's disease

Masashi Yoshitake1,2, Etsuko Maeshima2, Shinichiro Maeshima3

  • 1Faculty of Health Sciences, Kinjo University: 1200 Kasama-machi, Hakusan-shi, Ishikawa 924-8511, Japan.

Journal of Physical Therapy Science
|November 7, 2022
PubMed

Insights

Individuals with mild cognitive impairment (MCI) and Alzheimer's disease (AD) show reduced olfactory identification abilities. This suggests smell tests may aid in early dementia diagnosis and intervention planning.

Area of Science:

  • Neurology
  • Gerontology
  • Olfactory Science

Background:

  • Olfactory dysfunction is increasingly recognized as an early non-motor symptom in neurodegenerative diseases.
  • Mild cognitive impairment (MCI) and Alzheimer's disease (AD) can affect sensory processing, including smell.

Purpose of the Study:

  • To investigate olfactory identification abilities in individuals with MCI and AD.
  • To identify specific odors that are difficult to recognize in these populations.

Main Methods:

  • A Japanese odor stick identification test (OSIT-J) was administered to three groups: MCI patients (n=12), AD patients (n=17), and cognitively healthy controls (n=30).
  • Scores were compared across groups, and the ratio of correct responses for individual odors was analyzed to pinpoint difficult-to-identify scents.

Main Results:

  • Both MCI and AD groups exhibited significantly lower OSIT-J scores compared to controls.
  • While pungent odor identification was similar across groups, AD patients could not identify cooking gas odor.
  • Food-related odor identification was impaired in both MCI and AD groups.

Conclusions:

  • Reduced olfactory identification ability is characteristic of MCI and AD compared to cognitively healthy older adults.
  • Olfactory assessment may be a valuable tool for early detection and intervention in dementia.
  • Consideration of olfactory function is important when planning therapeutic interventions involving olfactory stimuli for dementia patients.
Keywords:
Alzheimer’s diseaseMild cognitive impairmentOlfactory impairment

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