Olfactory Decline in Older Adults with Mild Cognitive Impairment with and without Comorbidities.

Katerina Touliou,Evangelos Bekiaris,Nicos Maglaveras

doi:10.3390/diagnostics11122228

Abstract

Over the past two decades, several studies have measured olfactory performance in Mild Cognitive Impairment (MCI). Deficits are observed in multiple olfactory domains, including odour detection threshold, identification, discrimination, and memory. In this study, the psychophysiological Sniffin’ Sticks smell screening test was administered to examine olfactory functioning in 145 older adults with MCI, a group with MCI and chronic comorbid conditions, and a healthy age-matched comparison group. We hypothesised that olfactory performance will deteriorate in the two MCI groups compared to the control group, even after assessing the known contributions of age and gender. The higher olfactory deterioration in the group with the MCI and the comorbidities in the first year disappeared in the second. This could mean that early consideration of the potential effect of other comorbidities that might affect olfaction should be taken and addressed, as they could easily mask the effect of cognitive decline and/or contribute to it. This study also found higher deterioration in smell identification in participants with MCI, as has been found repeatedly in similar research. Olfactory identification seems to be a more robust marker for discriminating people with MCI and without, and even discriminating between those with MCI and having other health problems.

Highlights

Earlier identification and diagnosis of individuals likely to develop Alzheimer’s disease (AD) is critical for potential intervention and treatment early in the course of the disease
mild cognitive impairment (MCI) is often regarded as an intermediate step between normal ageing and Alzheimer’s disease (AD), and the prediction of transition from one step to the has been the objective of several studies in the last decade, with focus being placed lately on olfactory deterioration as a potential prediction marker for moving from MCI to AD [1,2,3,4]
Olfactory decline can be found in 85% of individuals with early Alzheimer’s disease (AD), which makes it an attractive biomarker for the early identification of neurodegenerative diseases such as AD before any pathological implications become evident [11]

Summary

Introduction

Earlier identification and diagnosis of individuals likely to develop Alzheimer’s disease (AD) is critical for potential intervention and treatment early in the course of the disease. There has been intense focus on individuals at risk for developing dementia, in particular those with mild cognitive impairment (MCI). To this effect, recent studies of neuropsychological function in MCI aimed at early detection and prevention strategies. Memory deterioration is related to decline in smell sensation [5]. It is important, though, to keep in mind that olfaction is a sensory modality that deteriorates with age [6], more often in male than female individuals [7] and often with people being unaware of this decline [8,9]. Olfactory decline can be found in 85% of individuals with early Alzheimer’s disease (AD), which makes it an attractive biomarker for the early identification of neurodegenerative diseases such as AD before any pathological implications become evident [11]

Methods

Results

Conclusion