Association Between Olfactory Test Data with Multiple Levels of Odor Intensity and Suspected Cognitive Impairment: A Cross-Sectional Study

Article type: Research Article

Authors: Sato, Shuichi^{a; *} | Imaeda, Takao^a | Mugikura, Shunji^{b; c; d; e} | Mori, Naoko^{b; f} | Takanashi, Masaki^a | Hayakawa, Kazumi^a | Saito, Tomo^b | Taira, Makiko^{b; d; e} | Narita, Akira^b | Kogure, Mana^{b; e} | Chiba, Ippei^{b; e} | Hatanaka, Rieko^{b; e} | Nakaya, Kumi^{b; e} | Kanno, Ikumi^{b; e} | Ishiwata, Ryosuke^b | Nakamura, Tomohiro^b | Motoike, Ikuko N.^b | Nakaya, Naoki^{b; e} | Koshiba, Seizo^{b; c} | Kinoshita, Kengo^{b; c; g; h} | Kuriyama, Shinichi^{b; e; i} | Ogishima, Soichi^{b; c} | Nagami, Fuji^{b; c} | Fuse, Nobuo^{b; c; e} | Hozawa, Atsushi^{b; e}

Affiliations: [a] Toyota Central Research and Development Laboratories, Inc., Nagakute, Japan | [b] Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan | [c] The Advanced Research Center for Innovations in Next-Generation Medicine, Tohoku University, Sendai, Japan | [d] Tohoku University Hospital, Sendai, Japan | [e] Tohoku University Graduate School of Medicine, Sendai, Japan | [f] Akita University Graduate School of Medicine, Akita, Japan | [g] Tohoku University Graduate School of Information Sciences, Sendai, Japan | [h] Institute of Development, Aging, and Cancer, Tohoku University, Sendai, Japan | [i] International Research Institute of Disaster Science, Tohoku University, Sendai, Japan

Correspondence: [*] Correspondence to: Shuichi Sato, Toyota Central Research and Development Laboratories Inc., Nagakute 480-1192, Japan. Tel.: +81 561 71 7122; E-mail: shuichi-sato@mosk.tytlabs.co.jp.

Abstract: Background:Olfactory function decline has recently been reported to be associated with a risk of cognitive impairment. Few population-based studies have included younger adults when examining the association between olfactory test data with multiple odor intensities and suspected cognitive impairment. Objective:We investigated the association between high-resolution olfactory test data with fewer odors and suspected cognitive impairments. We also examined the differences between older and younger adults in this association. Methods:The Japanese version of the Montreal Cognitive Assessment (MoCA-J) was administered to 1,450 participants, with three odor-intensity-level olfactometry using six different odors. Logistic regressions to discriminate suspected cognitive impairment were conducted to examine the association, adjusted for age, sex, education duration, and smoking history. Data were collected from the Program by Tohoku University Tohoku Medical Megabank Organization, with an additional olfactory test conducted between 2019 and 2021. Results:We generally observed that the lower the limit of distinguishable odor intensity was, the higher the MoCA-J score was. The combination of spearmint and stuffy socks contributed most to the distinction between suspected and unsuspected cognitive impairment. Furthermore, the association was significant in women aged 60–74 years (adjusted odds ratio 0.881, 95% confidence interval [0.790, 0.983], p = 0.024). Conclusions:The results indicate an association between the limit of distinguishable odor intensity and cognitive function. The olfactory test with multiple odor intensity levels using fewer odors may be applicable for the early detection of mild cognitive impairment, especially in older women aged 60–74 years.

Keywords: Alzheimer’s disease, cross-sectional studies, dementia tests, logistic models, mental status, odds ratio, olfactory disorders, risk, smell

DOI: 10.3233/JAD-230318

Journal: Journal of Alzheimer's Disease, vol. 95, no. 4, pp. 1469-1480, 2023