Association between olfactory function and cognitive impairment in dementia‐free older adults in Taiwan: A longitudinal cohort study

Background The olfactory impairment could be one of the earliest signs cognitive impairment. However, limited studies have evaluated function and domains in Asian older adults. This study aimed to relate olfaction with global domain-specific cognition Taiwan’s community-dwelling, non-demented Method cohort is part Taiwan Initiative for Geriatric Epidemiological Research, including 310 adults between 2015-2019 two repeated measures on function. Global (memory, executive function, attention, language) were assessed by Taiwanese version Montreal Cognitive Assessment (MoCA-T) a battery neuropsychological tests, respectively. Sniffin' Sticks-Odor Identification Test (SS-OIT) was utilized identify impaired olfaction. generalized linear mixed model used examine association SS-OIT over time, after adjustment age, sex, years education, apolipoprotein E ε4 status, presence depression, sleep quality, chronic respiratory diseases, smoking, practice effect follow-up time. Subgroup analyses also conducted. Result Better identification ability (i.e., increased score) associated better performance (MoCA-T: β = 0.14, 95% confidence interval 0.05-0.24), memory (logical - immediate delayed theme free recall: 0.06 0.09), (trail making test-A: 0.05 baseline, -0.03 interaction years), verbal fluency (β 0.08). Anosmia (SS-OIT score ≦8) [the lowest tertile (T1) vs. higher tertiles (T2+T3), adjusted odds ratio (aOR): 2.40 3.06], (T1 T2+T3, aOR 2.39). After stratified analyses, associations above remained significant non-carriers 0.19; memory: 0.08 0.11; fluency: 0.08), without diseases 0.14; 0.10; 0.10), depression 0.09; trail 0.04 -0.02 years; 0.09). Conclusion Impaired poor or Further research required validate our findings clarify underlying mechanism anosmia