Examining the Longitudinal Relationship Between Olfactory Dysfunction and Frailty in Community-Dwelling, older US Adults.

ABSTRACT

OBJECTIVE: Olfactory dysfunction is a "canary in the coalmine" for aging conditions. We evaluated olfactory dysfunction as a biomarker of early frailty in older adults living in the United States. STUDY DESIGN: Prospective, longitudinal, nationally representative study. SETTING: National Social Life, Health and Aging Project (NSHAP). METHODS: We examined data from 1061 community-dwelling older US adults. Odor identification (5-item Sniffin' Stick) and frailty scores were measured at baseline and 5-year follow-up. Multivariate logistic regressions evaluated the association between olfactory dysfunction and frailty at baseline in cross-section and over time in the transition from robust to prefrail to frail, adjusting for confounding factors measured at baseline. RESULTS: Older US adults who were anosmic at baseline were more likely to be frail 5 years later compared to normosmic peers (odds ratio [OR] 3.83, 95% confidence interval [CI] 1.10-13.31, P = .035). Examining changes in frailty stage over time, we found that anosmics were more likely to transition from prefrail to frail over 5 years (OR 3.25, 95% CI 1.31-8.08, P = .011). Interestingly, hyposmics did not show a similar trajectory toward frailty (P > .05). In contrast, olfactory dysfunction was not associated with frailty in cross-section (OR 0.90, 95% CI 0.43-1.89, P = .787, hyposmia; OR 0.72, 95% CI 0.15-3.35, P = .673, anosmia). CONCLUSION: Older US adults with anosmia face higher odds of becoming frail over 5 years, especially those in the prefrail stage. Olfactory dysfunction may serve as a surrogate marker for early-stage neurodegenerative diseases, which are strong contributors to frailty.