Sense of Smell May Predict Mortality in Older Adults

the MPR take:

Olfaction could predict 5-year mortality risk among older adults, suggests a new study in PLOS One. Over 3,000 community-dwelling older adults ages 57–85 were interviewed during 2005–2006, followed by a second interview from 2010–2011. Olfactory function was evaluated in the interviews using a validated odor identification test presented using five felt-tipped pens (rose, leather, orange, fish, and peppermint), where the respondents were asked to match the odor to one of four image/word prompts. Olfactory dysfunction was found to be an independent risk factor for death – more so than heart failure, lung disease, cancer, and other causes of death. After accounting for potential confounding factors, anosmic older adults had a risk of death three times that of normosmic individuals and did not result from nutrition, cognitive function, mental health, smoking and alcohol abuse or frailty. This is the first known study with evidence that olfactory dysfunction may be a strong predictor of 5-year mortality in a nationally representative sample of older adults. The researchers hypothesize that the olfactory system may indicate deterioration in age-related regenerative capacity more broadly or as a marker of physiologic repair function due to stem cell turnover, and that its decline is not a direct cause of mortality.

Prediction of mortality has focused on disease and frailty, although antecedent biomarkers may herald broad physiological decline. Olfaction, an ancestral chemical system, is a strong candidate biomarker because it is linked to diverse physiological processes.