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Loss of the sense of smell may predict mortality risk among older people

Frailty and dementia often signal increased risk for mortality among older people. But can the loss of olfaction—the sense of smell—also be a significant indicator of mortality risk? An NIH-supported study involving thousands of older people showed those who could no longer detect or distinguish odors were four times more likely to die within five years than those with normal olfaction. The findings are the first to indicate the importance of olfaction in mortality risk for older adults.

Dr. Jayant M. Pinto led the University of Chicago researchers reporting the findings in the Oct. 1, 2014 online issue of PLOS ONE. The work was funded in part by NIA, the Office of Women’s Health Research, the Office of AIDS Research, and the Office of Behavioral and Social Sciences Research, all at the National Institutes of Health.

The researchers tested the olfaction of some 3,000 older volunteers in the National Social Life, Health and Aging Project, a University of Chicago-run longitudinal study seeking to better understand the various factors that contribute to the health and well-being of older, community-dwelling Americans. Study participants, aged 57 to 85, were interviewed at home and asked to identify five odors (rose, leather, orange, fish, and peppermint) embedded in felt-tipped pens. The test results were rated from a total loss of olfaction, to some decline, to normal function. Five years later, the researchers examined mortality rates among the volunteers.

The results were dramatic, even when controlling for demographic factors, such as age, gender, race and socioeconomic status, as well as medical conditions, smoking, and alcohol use. At the end of the five-year study, 39 percent of volunteers with no sense of smell had died, compared to 19 percent of those with declines in olfaction and 10 percent of those with normal olfaction. The results suggest that olfactory function is a strong indicator of risk for mortality in older people.

Reference: Pinto JM, et al. Olfactory dysfunction predicts 5-year mortality in older adults. PLoS One. Oct 1, 2014. doi: 10.1371/journal.pone.0107541