Related Experiment Video
Updated: Mar 9, 2026
10:42
A Free-breathing fMRI Method to Study Human Olfactory Function
Published on: July 30, 2017
10.2K
A quantitative meta-analysis of olfactory dysfunction in mild cognitive impairment
David R Roalf1, Madelyn J Moberg1, Bruce I Turetsky1
1Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA.
Journal of Neurology, Neurosurgery, and Psychiatry
|January 1, 2017
Summary
Olfactory deficits are common in mild cognitive impairment (MCI), particularly in odour identification. This suggests smell tests could help screen for Alzheimer's disease (AD) risk.
Area of Science:
- Neuroscience
- Gerontology
- Psychology
Background:
- Alzheimer's disease (AD) is linked to olfactory deficits.
- Olfactory dysfunction may indicate cognitive decline and dementia.
- Mild cognitive impairment (MCI) is a transitional stage between normal aging and dementia.
Purpose of the Study:
- To conduct a meta-analysis on olfactory deficits in MCI.
- To characterize the nature and extent of olfactory impairments in MCI patients.
Main Methods:
- Comprehensive literature search of PubMed, MEDLINE, and PsychInfo databases up to June 2016.
- Meta-analysis of 31 articles including 1993 MCI patients and 2861 healthy older adults (HOA).
- Weighted effect size computation to control for sample size differences.
Main Results:
- Significant, moderate-to-large olfactory deficits found in MCI compared to HOA (d=-0.76).
- Odour identification tests showed larger effect sizes than detection or memory tests.
- Male MCI patients exhibited greater olfactory deficits; older females performed better.
Conclusions:
- Olfactory deficits are a robust finding in MCI.
- Impaired odour identification in MCI mirrors deficits seen in AD.
- Odour identification tests are recommended for screening individuals at risk for AD.
Related Concept Videos
01:25Olfaction
49.4K
The sense of smell is achieved through the activities of the olfactory system. It starts when an airborne odorant enters the nasal cavity and reaches olfactory epithelium (OE). The OE is protected by a thin layer of mucus, which also serves the purpose of dissolving more complex compounds into simpler chemical odorants. The size of the OE and the density of sensory neurons varies among species; in humans, the OE is only about 9-10 cm2.
The olfactory receptors are embedded in the cilia of the...
The olfactory receptors are embedded in the cilia of the...
49.4K
01:03Olfactory Receptors: Location and Structure
13.6K
The process of olfaction, also known as the sense of smell, is a sophisticated chemical response system. The specialized sensory neurons that facilitate this process, known as olfactory receptor neurons, are situated in an upper segment of the nasal cavity, known as the olfactory epithelium. Olfactory sensory neurons are bipolar, with their dendrites extending from the epithelium's apex into the mucus that lines the nasal cavity. Airborne molecules, when inhaled, traverse the olfactory...
13.6K