Olfactory identification deficits are associated with cognitive decline in Chinese older adults: The Taizhou Imaging Study

• Published in: Alzheimer's & dementia Vol. 16
• Main Authors: Jiang, Yanfeng, Tan, Ziyi, Zhang, Kexun, Zhu, Zhen, Wang, Yingzhe, Li, Peixi, Jin, Li, Dong, Qiang, Cui, Mei, Chen, Xingdong
• Format: Journal Article
• Language: English
• Published: 01.12.2020
• ISSN: 1552-5260; 1552-5279
• DOI: 10.1002/alz.040135

Background Olfaction function has emerged as a potential predictor of cognitive decline and dementia recently. We accessed the association of olfaction and cognitive function in a Chinese cohort. Method Participants in this study were part of the community‐based Taizhou Imaging Study. At the first wave of cognitive function follow‐up, 770 individuals underwent neuropsychological testing from July 2018 to August 2019, including four cognitive domains‐memory, executive function and attention, visuospatial function, and language. Mini‐Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) were used to assess participants’ global cognition. Among them, 686 participants underwent olfactory identification testing using 12‐item Sniffin’s Sticks test. Dementia and mild cognitive impairment (MCI) were adjudicated by a committee of experts, according to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM‐IV) and Petersen RC’s criteria, respectively. After data quality control, 684 participants were included in this analysis (Figure 1). Beta regression was used to evaluate the association between olfaction and cognitive function (continuous variables), logistic regression was used to assess the association between olfaction and cognitive status (categorical variable). Potential confounders were adjusted in two models: Model 1 was adjusted for age, sex, and years of education; Model 2 was additionally adjusted for smoking, alcohol consumption, body mass index, exercise, hypertension, diabetes, and hyperlipidemia. Result A total of 54 (7.9%) individuals were diagnosed as dementia, 165 (24.1%) individuals were adjudicated as MCI (Table 1). In the fully adjusted Model 2, the associations remained significant (Beta = 0.062 and 0.093, respectively; both P <0.001) (Table 2). Olfactory identification scores were associated with domain‐specific cognitive function scores in Model 2 (visuospatial function: Beta = 0.072, P = 0.003; short delay recall: Beta = 0.120, P <0.001; long delay recall: Beta = 0.057, P = .010; language: Beta = 0.107, P <0.001). Moreover, we found olfactory identification was negatively associated with MCI in Model 2 (odds ration [OR]: 0.88; 95% confidence interval [CI]: 0.81, 0.96) and dementia (OR: 0.76; 95% CI: 0.66, 0.87) (Table 3). Conclusion Olfactory identification are associated with both global and domain‐specific cognitive function and could serve as a protector for cognitive decline.