Characterizing the olfaction and dementia association in the community-based ARIC study

INTRODUCTION Few studies have characterized the association of olfaction with dementia in detail across diverse sociodemographic subgroups. METHODS We examined the association of one-time-point olfactory status with incident dementia overall and by age, race, sex, and apolipoprotein E (APOE) epsilon 4 status (n = 4470, mean age: 75 +/- 5 years, 21% Black), and 5-year olfactory change with incident dementia (n = 2658) in the community-based Atherosclerosis Risk in Communities (ARIC) study. RESULTS Compared to good olfaction, moderate olfaction (hazard ratio [HR]: 1.53, 95% confidence interval [CI]: 1.26 to 1.86), hyposmia (HR: 2.24, 95% CI: 1.81 to 2.78), and anosmia (HR: 3.47, 95% CI: 2.77 to 4.34) were all associated with higher dementia hazard; these associations were consistent across age, race, sex, and APOE epsilon 4 groups. The absolute risk difference between anosmia and good olfaction was higher in APOE epsilon 4 carriers than in non-carriers. Those with stable anosmia and converting from normal olfaction to anosmia over time showed particularly strong associations. DISCUSSION Olfactory impairment was robustly associated with incident dementia, with strongest associations in those with persistent impairment and greater olfactory decline over similar to 5 years.