Simple Smell Identification Test Using Three Odorants to Detect Cognitive Decline: Investigation in Community-dwelling Volunteers

Abstract

Background: The number of aging patients with dementia has been increasing in several countries, and a screening method for the early detection of dementia is needed. Objectives: The aim of this study was to evaluate a simple smell identification test for its ability to detect cognitive decline. Subjects and Methods: A total of 659 participants from the 2016 Iwaki Health Promotion Project aged ≧ 40 years were included. Participants underwent a smell identification test using three odorants, namely, India ink, Japanese cypress wood, and curry, out of the Odor Stick Identification Test for the Japanese （OSIT-J） and mini-mental state examination （MMSE） to examine their cognitive function. Results: In analysis of covariance, a statistically significant trend between the age and scores of the three odorants and between the scores of the three odorants and MMSE scores was observed. In multiple regression analysis, the MMSE scores significantly correlated with the scores of the simple smell identification test. From the viewpoint of sensitivity and positive likelihood, the values were not sufficient for screening. Conclusions: A simple smell identification test using three odorants might be useful for the early detection of dementia.