Poor Olfaction as a Marker of Impending Health Problems and Age Acceleration in Older Adults

Abstract Up to a quarter of older US adults have a poor sense of smell, a sensory impairment that most do not even realize they have. Nonetheless, poor olfaction independently predicts short-term and long-term mortality, and adversely affects nutrition, safety, and quality of life. Poor olfaction has been best studied as one of the most important early symptoms of Alzheimer’s disease and Parkinson’s disease. Our recent research suggests that poor olfaction may have much broader health implications than just neurodegenerative disease associations. We hereby propose the first comprehensive study ever undertaken to answer a question of great clinical and public health importance: “What does a poor sense of smell sometimes signify for the health of older adults?” above and beyond neurodegenerative diseases. We will leverage extensive prospective data from two well- established community-based biracial cohorts with comparable populations, study design, and data collection. To our knowledge, the Health ABC and ARIC studies represent the best data available to address the proposed research question. With 8,630 older US adults aged ≥65 years, 56.6% women and 27.6% blacks, this study represents the largest data to date with both objectively tested sense of smell and longitudinally assessed health outcomes. Specific hypotheses are: 1) Poor olfaction is associated with risk of multiple major diseases in older adults; 2) Poor olfaction predicts faster functional declines and the development of frailty in older adults; and 3) Poor olfaction contributes to higher mortality in older adults through diseases, functional declines, and frailty. Our multidisciplinary team of epidemiologists, biostatisticians, and clinical scientists has a proven history of productive collaborations. The scientific rigor of this project is assured by the large sample size and meticulously collected health data, carefully planned statistical analyses, cross-validation of study findings, strategized pooled analyses, and a very experienced multi-institutional research team. Innovation: This proposal is highly innovative and may help shift the paradigm of how medical practitioners see the need to regularly assess olfaction in older adults. Significance: This study will significantly advance understanding of potentially profound health implications of poor olfaction in older adults, and thus lay solid foundation for future research to improve the health, quality of life, and survival of older adults.