Another inconclusive study
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) are known to deteriorate with age, there is no scientific evidence to support the claim that a poor sense of smell can predict death.
One of the first studies to investigate the mysterious link between sense of smell and longevity was published last month in the journal Annals of Internal Medicine.
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 and were grouped into categories based on their ability to identify 12 common odors.
Participants were tracked for 13 years or until they died, whichever came first.
Study results suggest that individuals with a poor sense of smell are nearly twice as likely to die within 10 years. This risk was not affected by sex, race, or lifestyle.
“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, only 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” could be used to predict the onset of neurodegenerative disease.