Older adults who’ve lost their sense of smell — namely, the ability to pick up on strong odors like smelly socks or bacon sizzling in a pan — could be at an increased risk of death within five years, according to a study involving more than 3,000 people ages 57 to 85.
The study, which published recently in the science journal PLOS ONE, revealed in a smell test conducted in 2005, that nearly 40 percent of subjects who failed died within five years, compared to a 19 percent death rate within five years for those with moderate smell loss. Ten percent of the test subjects were determined to have a healthy sense of smell.
During the test, “Sniffin’ Sticks,” which resemble felt-tip pens, were loaded with five different scents — peppermint, fish, orange, rose or leather — that subjects were asked to identify.
Nearly 78 percent of those tested who were able to identify at least four of the five scents, were classified as having a normal sense of smell.
Almost 20 percent got two or three of the scents right, while the remaining 3.5 percent could correctly identify one or none of the five.
“Compared to a person with a normal sense of smell, a person with an absent sense of smell has three times greater risk of dying within a five-year span,” Dr. Jayant Pinto, the study’s lead author, said this month in a phone interview.
“What this tells us is your sense of smell is a great indicator of your overall health,” said Pinto, an associate professor at the University of Chicago, who specializes in genetics and treatment of olfactory and sinus disease.
Pinto, who likened the loss of smell to a canary in a coal mine, added that, “it doesn’t cause death, but it’s an early warning that something has gone badly wrong.”
In 2010 and 2011, the survey team confirmed which participants were still alive. During the five years, 430 of the subjects, or 12.5 percent, had died.
Researchers also conducted interviews to adjust for variables and risk factors, such as age, smoking, alcohol use, overall health and socioeconomic status. In the end, those with greater smell loss when first tested were substantially more likely to have died five ears later.
“It predicted it quite strongly,” Pinto said.
In a study published last year in the Journals of Gerontology, African-Americans and Latinos lost their ability to smell faster than whites. The participants, who included information about their race and ethnicities, answered questionnaires about their physical and mental health, social and financial resources, education, and alcohol or substance abuse.
The study concluded that African-Americans are more likely to suffer from a related health disparity not explained by gender, education, cognition, physical or mental health, and health behaviors.
“We have long known that men begin to lose their sense of smell some years sooner than women, but this [particular study] is the first to point to racial or ethnic differences,” Pinto said. “What surprised us was the magnitude of the difference. The racial disparity was almost twice as large as the welldocumented difference between men and women.”
Meanwhile, according to officials at the National Institutes of Health (NIH) in Bethesda, Maryland, the sense of smell, which can diminish significantly past age 70, may be related to loss of nose nerve endings and lack of mucus produced in the nose.
Also, while decreased smell can lessen interest and enjoyment in eating, the risk of danger increases because a person cannot smell odors such as natural gas or even smoke from a fire just starting.
In addition, researchers at the Atlanta-based Centers for Disease Control and Prevention report that the most common causes of permanent smell loss are upper respiratory infections, head trauma or injury, and chronic rhinosinusitis.
Other less common causes of smell loss, they report, include chronic alcoholism, epilepsy, and neurological disorders such as multiple sclerosis, Alzheimer’s disease, and Parkinson’s disease.