A poor sense of smell may indicate an older person’s higher risk of pneumonia, research finds.
An acute loss of smell is one of the most common symptoms of COVID-19, but for two decades it has been linked to other conditions, such as Parkinson’s disease and dementia.
“About a quarter of adults 65 years or older have a poor sense of smell,” says Honglei Chen, a professor in the department of epidemiology and biostatistics at Michigan State University’s College of Human Medicine. “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.”
For the study, Chen and his team found a possible link between poor sense of smell and a higher risk of pneumonia hospitalization. They analyzed 13 years of health data from 2,494 older adults, ages 71-82, from metropolitan areas of Pittsburgh, Pennsylvania, and Memphis, Tennessee. This study aimed to examine whether a poor sense of smell in older adults is associated with a higher future risk of developing pneumonia.
Chen’s research appears in the journal The Lancet Healthy Longevity.
The participants took a Brief Smell Identification Test, or B-SIT, using common smells such as lemons and gasoline, to determine if their sense of smell was good, moderate, or poor. Then, the participants were monitored for the next 13 years using clinical exams and follow-up phone calls to identify hospitalization due to pneumonia.
The researchers found that compared with participants who had a good sense of smell, participants with a poor sense of smell were about 50% more likely to be hospitalized with pneumonia at any time point during the 13-year follow-up. Among participants who had a poor sense of smell and who had never before had pneumonia, the risk of having the first-ever pneumonia was about 40% higher.
“To our knowledge, this study provides the first epidemiological evidence that poor olfaction is associated with a long-term higher risk of pneumonia in older adults,” says Yaqun Yuan, a postdoctoral fellow in Chen’s research group.
This study provides evidence that a poor sense of smell may have broader health implications beyond its connections to Parkinson’s disease and dementia.
“This is just an example of how little we know about this common sensory deficit,” Chen says. “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. To understand what this common sensory deficit means for our health, we need to think outside of the box.”
Source: Emilie Lorditch for Michigan State University