Older adults who have a decline in the ability to identify scents could be at risk of mortality within five years.
In the first in-home study of social relationships and health, researchers found a link between sense of smell and mortality risk, PLOS reported.
The findings were made as part of the National Social Life, Health and Aging Project (NSHAP), which looked at 3,000 men and women between the ages of 57 and 85. The researchers assessed the participants' ability to pick out five common odors from a set of four choices. The scents included: "peppermint, fish, orange, rose and leather."
In a second survey that took place five years later (between 2010 and 2011) the team looked at which participants were still alive. During this period 12.5 percent of the original participants had passed away.
The researchers determined 39 percent of the study subjects who failed the first smell test died before the second survey took place, compared to 19 percent who were determined to have moderate smell loss and 10 percent with a healthy sense of smell.
For participants who already had high risk factors, significant smell loss more than doubled their probability of death within five years. After the team adjusted for "age, gender, socioeconomic status (as measured by education or assets), overall health, and race" those with high rates of smell loss were significantly more likely to die within five years.
The researchers are not sure exactly what is causing this link, but a decreased sense of smell proved to predict mortality better than factors such as heart disease and cancer, only being beaten out by severe liver damage.
"We think loss of the sense of smell is like the canary in the coal mine," said the study's lead author Jayant M. Pinto, MD, associate professor of surgery at the University of Chicago. "It doesn't directly cause death, but it's a harbinger, an early warning system, that something has already 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 findings were published Oct. 1 in the journal PLOS ONE.
