AUTHOR=Dong Yi , Wang Yongxiang , Liu Keke , Liu Rui , Tang Shi , Zhang Qinghua , Ekström Ingrid , Laukka Erika J. , Du Yifeng , Qiu Chengxuan 

TITLE=Olfactory Impairment Among Rural-Dwelling Chinese Older Adults: Prevalence and Associations With Demographic, Lifestyle, and Clinical Factors

JOURNAL=Frontiers in Aging Neuroscience

VOLUME=Volume 13 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/aging-neuroscience/articles/10.3389/fnagi.2021.621619

DOI=10.3389/fnagi.2021.621619

ISSN=1663-4365

ABSTRACT=Objective Olfactory impairment (OI) refers to decreased (hyposmia) or absent (anosmia) ability to smell. We sought to estimate the prevalence and correlates of OI among rural-dwelling Chinese older adults. 
Methods This population-based cross-sectional analysis included 4514 participants (age ≥65 years; 56.7% women) from the Multidomain Interventions to Delay Dementia and Disability in Rural China. The 16-item Sniffin’ Sticks identification test (SSIT) was used to assess olfactory function. OI was defined as the SSIT score ≤10, hyposmia as SSIT score of 8-10, and anosmia as SSIT score <8. Multivariable logistic regression models were used to examine factors associated with OI.   
Results The overall prevalence was 67.7% for OI, 35.3% for hyposmia, and 32.5% for anosmia. The prevalence increased with age for OI and anosmia, but not for hyposmia. The multivariable-adjusted odds ratio (OR) of OI was 2.10 (95% CI 1.69-2.61) for illiteracy and 1.41 (1.18-1.70) for elementary school (vs. middle school or above), 1.30 (1.01-1.67) for current smoking (vs. never smoking), 0.86 (0.74-0.99) for overweight and 0.73 (0.61-0.87) for obesity (vs. normal weight), 4.21 (2.23-7.94) for dementia, 1.68 (1.23-2.30) for head injury, and 1.44 (1.14-1.83) for sinonasal disease. Illiteracy in combination with either male sex or diabetes was significantly associated with an over two-fold increased OR of OI (p for interactions<.05).
Conclusion OI is highly prevalent that affects over two-thirds of rural-dwelling older adults in China. OI is correlated with illiteracy, current smoking, dementia, head injury, and sinonasal disease, but negatively associated with overweight or obesity. OI as a potential clinical marker of neurodegenerative disorders among older adults deserves further investigation.