With aging might come a loss of some eyesight or hearing, but it's the loss of the sense of smell that a new study says could indicate death could be looming.
According to research published this month in the journal PLOS One, 39 percent of people in a study who failed a scent test died within a five-year period. Conversely, 19 percent of those who had a moderate loss of smell and 10 percent of those with their sense of smell intact died within the same period of time.
"We think loss of the sense of smell is like the canary in the coal mine," the study's lead author Dr. Jayant Pinto with the University of Chicago, said in a statement. "It doesn't directly cause death, but it's a harbinger, an early warning that something has gone badly wrong, that damage has been done. Our findings could provide a useful clinical test, a quick and inexpensive way to identify patients most at risk."
The study involved more than 3,000 participants between the ages of 57 and 85 years old. The smell test involved "Sniffn'Sticks," which is a pen-like devices that emits scents. Study subjects were asked to identify smells with the difficulty of the scent increasing from peppermint to fish to orange to rose to leather.
When the study authors followed up with the study participants five years later and adjusted for other variables that could skew their results, they found that even a a mild loss of smell was associated with a greater risk of death.
"This evolutionarily ancient special sense may signal a key mechanism that affects human longevity," Dr. Martha McClintock, a senior author on the study, said.
The study authors said that the loss of smell can impact eating and hygiene habits negatively or could limit a person's ability to detect dangers such as spoiled food or a gas leak.
McClintock also said that the stem cells in the olfactory system can regenerate. A loss of the ability to smell could "signal a decrease in the body's ability to rebuild key components that are declining with age and lead to all-cause mortality."
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