For years, people have considered a poor sense of smell as an indicator that death is near. And while a person’s senses (including smell) deteriorate with age, there is no scientific evidence to support the claim that a poor sense of smell can predict death.
The journal Annals of Internal Medicine published one of the first studies to investigate the mysterious link between sense of smell and longevity.
The study, conducted by Michigan State epidemiologist Honglei Chen, involved nearly 2,300 participants ages 71-82. Participants took a “smell test” in the year 2000. Researchers then grouped them into categories based on their ability to identify 12 common odors.
Researchers tracked participants for 13 years or until they died, whichever came first.
Study results suggest that individuals with poor sense of smell are nearly twice as likely to die within 10 years. Sex, race, or lifestyle did not affect this risk.
“Poor olfaction among older adults with excellent to good health may be an early warning sign for insidious adverse health conditions that eventually lead to death,” wrote Chen.
While previous studies have suggested that olfactory decline could be associated with the onset of neurodegenerative diseases like dementia and Alzheimer’s, this theory accounts for only 22% of Chen’s results.
“My suspicion is [the] process of smell in older adults probably has much broader potential health implications than what we already know about,” says Chen.
The olfactory system is linked to the central nervous system, so Chen’s theory makes sense.
Unfortunately, Chen’s study was unable to identify a cause and effect relationship between sense of smell and neurodegenerative disease. It only suggests the possibility of an association.
In response to false claims by publications like The Guardian, the UK National Health Service made it clear that Chen’s findings do not support claims that a “smell test” can predict the onset of neurodegenerative disease.