Researchers from Michigan State University found that in older adults, a poor sense of smell can indicate a higher risk of pneumonia.
One of the most common symptoms of COVID-19 is an acute loss of smell, which has been linked to other diseases including Parkinson’s disease and dementia for the past two decades. The study was published in the Lancet Healthy Longevity journal.
Mr. Honglei Chen, a Professor in the Department of Epidemiology and Biostatistics within MSU’s College of Human Medicine stated that “about a quarter of adults 65 years or older have a poor sense of smell. Unlike vision or hearing impairment, this sensory deficit has been largely neglected; more than two-thirds of people with a poor sense of smell do not know they have it.”
Mr. Chen and his team found a potential correlation between a poor sense of smell and a higher risk of pneumonia hospitalization in a first-of-its-kind study.
They analyzed 13 years of health data from 2,494 older adults, aged 71 to 82, in the Pittsburgh, Pennsylvania, and Memphis, Tennessee metropolitan areas.
The goal of this study was to examine whether having a poor sense of smell in older people is linked to a higher risk of pneumonia in the future.
The participants were given a Brief Smell Identification Test (B-SIT), to decide if their sense of smell was strong, moderate, or bad, using common smells like lemons and gasoline. The participants were then followed for the next 13 years, with clinical tests and follow-up phone calls to detect pneumonia-related hospitalizations.
Participants with a poor sense of smell were around 50 percent more likely to be hospitalized with pneumonia at some stage during the 13-year follow-up than those with a good sense of smell, according to the researchers.
The risk of first-ever pneumonia was around 40 percent higher among participants (with a poor sense of smell) who had never pneumonia before.
Mr. Yaqun Yuan, a postdoctoral fellow in Mr. Chen’s research group remarked that “to our knowledge, this study provides the first epidemiological evidence that poor olfaction (sense of smell) is associated with a long-term higher risk of pneumonia in older adults.”
This study provides novel evidence that a poor sense of smell has health effects beyond Parkinson’s disease and dementia.
“This is just an example of how little we know about this common sensory deficit. Either as a risk factor or as a marker, poor sense of smell in older adults may herald multiple chronic diseases beyond what we have known about. We need to think out of the box,” Mr. Chen concluded.