A novel olfactory threshold test for screening cognitive decline among elderly people

Abstract

Olfactory impairment is associated with dementia and is a potential early biomarker of cognitive decline. We developed a novel olfactory threshold test called Sniff Bubble using rose odor-containing beads made with 2-phenylethyl alcohol. We aimed to define cut-off scores for this tool to help identify cognitive decline among elderly people. In total, 162 elderly people (mean age ± SD: 73.04 ± 8.73 years) were administered olfactory threshold and neurocognitive tests. For analyses, we divided the participants into two groups based on cognitive functioning, namely cognitive decline (n = 44) and normal cognition (n = 118) groups. The Sniff Bubble and YSK olfactory function test for olfactory threshold and the Structured Clinical Interview for DSM-5 Disorders-Clinician Version and Korean version of the Consortium to Establish a Registry for Alzheimer’s Disease assessment packet for neurocognitive functioning were used. We used K-means cluster analyses and receiver operating characteristic (ROC) analyses to identify the most appropriate cut-off value. We established a positive correlation between the Sniff Bubble and neurocognitive function test scores (r = 0.431, p < 0.001). We defined the cut-off score, using the ROC curve analyses for Sniff Bubble scores, at 3 and higher with an area under the curve of 0.759 (p < 0.001). The Sniff Bubble test can adequately detect cognitive decline in elderly people and may be used clinically as the first step in the screening process.

Verification of the association between cognitive decline and olfactory dysfunction using a DEmentia screening kit in subjects with Alzheimer's dementia, mild cognitive impairment, and normal cognitive function (DESK study): A multicenter, open-label, interventional study

“…In terms of the diagnostic utility of the DESK assessment tool used in this study, we found a high diagnostic utility with all combinations. Previous studies have demonstrated associations between cognitive function decline and olfactory function, including in Japanese and Asian populations, and indicate that impairment in olfactory discrimination can predict future cognitive decline [ 20 , 27 , 28 ]. These results suggest that the greater a patient's decline in cognitive function, the higher the possibility of reduced olfactory function occurring due to cerebral limbic system or olfactory nerve neuropathy [ 29 , 30 ].…”

Diffusion Tensor Imaging Study of Olfactory Identification Deficit in Patients With Mild Cognitive Impairment

“…The most commonly used odor identification test is the University of Pennsylvania Smell Identification Test (UPSIT), however, it takes too long to administer by using 40 scents. Furthermore, too much odor identification can be affected by differences in region, culture, and individual experiences, so it is complicated to use as a screening test for the elderly ( Kim et al, 2020 , 2021 ). The “Sniffin’ Sticks” Test (SST) is another widely used odor test, but its applicability is limited because of the high cost and the regional-cultural differentiation of odor recognition ( Demir et al, 2021 ).…”

Deficits in color detection in patients with Alzheimer disease

“…Early detection of dementia provides a number of advantages, including the prevention of risk factors and timely appropriate treatments [ 5 , 6 ]. Although AD is currently incurable, there are pharmacologic and cognitive treatment options that alleviate dementia symptoms and slow disease progression [ 7 ]. Moreover, patients can establish their treatment plans for comorbid diseases in advance.…”

“…However, to date, there are no established peripheral biomarkers that are simple, inexpensive, and readily available in clinical settings. Olfactory and retinal changes have been suggested as potential peripheral biomarkers of AD [ 7 , 16 ]. Kim et al developed a novel olfactory threshold test for dementia screening that adequately detected cognitive decline in older patients [ 7 ].…”

“…Olfactory and retinal changes have been suggested as potential peripheral biomarkers of AD [ 7 , 16 ]. Kim et al developed a novel olfactory threshold test for dementia screening that adequately detected cognitive decline in older patients [ 7 ]. In addition, retinal changes are of great interest as potential biomarkers of AD [ 16 ].…”