Losing one's sense of smell is a strong predictor that death is near -- and it possibly could be used as an early alert about serious health problems.
That's the conclusion of a study of older adults published this week in the journal PLOS One, which found that those who failed a smelling test were much more likely to die within five years.
Inability to sense odors "doesn't directly cause death, but it's a harbinger, an early warning that something has gone badly wrong," the study's lead author, Dr. Jayant M. Pinto, an associate professor of surgery at the University of Chicago, said in a statement.
In the study, researchers gave a smelling test to about 3,000 people ages 57 to 85. The volunteers were presented with five odors -- peppermint, fish, orange, rose and leather -- one at a time and asked to identify them. (They didn't have to respond off the tops of their heads, the study says: Researchers provided four possible answers for each scent.)
Five years later, the researchers checked back.
Nearly 40% of the people who "failed" the test, correctly identifying none or only one of the scents, had died in the interim, the study found. That's compared with 19% of those who correctly identified two or three of the smells and 10% of those who correctly identified at least four.
Even after results were adjusted for age, gender, race, overall health and socioeconomic status, the smell test still was a strong predictor of five-year mortality, the study found. Indeed, it was stronger predictor than emphysema, cancer, heart attack, stroke, diabetes or congestive heart failure.
It's unclear how sense of smell is related to mortality. The study did not examine the causes of death of volunteers who passed away.
But with further study, "our findings could provide a useful clinical test, a quick and inexpensive way to identify patients most at risk," Pinto said.