Could our sense of smell give us an early warning of looming health problems?
According to new research, it could be a potent indicator.
Only in this case, it isn’t about what a person smells, but what they don’t smell, that’s truly telling.
Research published in
These findings held true across racial and gender lines. They even applied to healthier people.
It’s a finding that may have implications on how doctors conduct checkups with older patients.
“People regularly are screened for hearing and vision, but in the future, as we understand the details between sense of smell and health consequences, maybe it’s not a bad idea to check sense of smell at any checkup,” Dr. Honglei Chen, an epidemiologist at Michigan State University and lead author of the study, told Healthline.
Prior studies have indicated that a poor sense of smell is a possible early predictor of Parkinson’s disease.
It was this research that intrigued Chen.
“I’m more of a Parkinson’s epidemiologist, so my interest in studying this came from the perspective of Parkinson’s research,” he explained. “As much research goes on, I think that sense of smell is probably a much more important sensory deficit in the older populations, above and beyond Parkinson’s disease.”
While earlier studies looked at a link between sense of smell and Parkinson’s, Chen said he wanted to take a more granular look.
“Previous studies are fairly limited in terms of follow-up and also only look at mortality,” he said. “I wanted to look into possible explanations. I’m trying to look into whether, long term, sense of smell is predictive of overall mortality in the older population, and also what’s responsible for this possible increase in mortality.”
Researchers looked at data from nearly 2,300 participants over a 13-year period. These men and women were all between 71 and 82 years old, and came from different racial backgrounds.
Researchers reported that different demographic factors had minimal effect, but sense of smell was a major predictor, as those who couldn’t smell as well were 46 percent more likely to die at the 10-year mark.
Chen’s team’s findings only explain about 30 percent of the cases of increased mortality.
In these cases, the increased risk of death can be linked to Parkinson’s disease or dementia.
But in the other cases where a poor sense of smell predicted a person’s death, things are a little murkier.
While there’s a connection between sense of smell and mortality, the exact reasons for this connection are unclear.
“This study found that 72 percent of the risk linking impaired ability to smell and death is unexplained, but may be related to insidious or chronic health issues that often progress over time, such as hypertension and cardiovascular disease,” explained Dr. Robert Glatter, an emergency physician at Lenox Hill Hospital in New York.
“Even if you control for issues such as race and gender, a poor sense of smell explained 70 percent of the differences that were associated with timing of death,” Glatter told Healthline. “This could make it a useful tool to look at overall health and risk of death in an older, healthy population.”
Chen says he hopes these questions will be answered in future studies.
In particular, he’d like to follow up this research and shed some light on the other 70 percent. But the data as it currently stands could still be useful for health professionals.
“The research suggests that sense of smell is an early and sensitive marker for poor health that is already ongoing, but still not clinically recognizable by the patient or their doctors,” said Chen.
Glatter theorizes that smell test screening could be useful in the hospital emergency ward where he works.
“The study opens an interesting question of whether screening older persons for impaired sense of smell when they present to the emergency department may be a potential way to risk-stratify them for future adverse outcomes,” he said.
Overall, the study has shed new light on the connection between sense of smell and mortality.
But with many cases unexplained and more research forthcoming, what’s the average person to do with this information?
For starters, the youngest person the study looked at was 71 years old. So while there may or may not be the same connection between sense of smell and health outcomes in younger people, the research hasn’t looked into this population.
But for older people, even those in good health, sense of smell certainly appears to be an early warning system for problems in the body.
“We are talking about more progressive, permanent decrease in sense of smell,” said Chen. “So if you have sense of smell problems for temporary reasons, it’s probably not much to worry about. But for older populations, if they have a persistent loss in their sense of smell, I would suggest they probably talk to their doctor.”
In older people, the loss of sense of smell can be an early predictor of health issues.
Those aged 71 and older are 46 percent more likely to die within 10 years if they’ve lost their sense of smell.
The exact machinations of this process and the exact connection between sense of smell and the ailment that eventually kills a person are largely unknown at this point.
Older adults should speak to their doctor if they’ve noticed their sense of smell disappearing.