In a recent study conducted by researchers at Johns Hopkins Medicine, the team uncovered significant evidence of a relationship between a decreased sense of smell and a heightened risk of developing late-life depression.
According to the researchers, the study does not prove causation. Nonetheless, they believe that the link may act as a critical overall health indicator.
“We’ve seen repeatedly that a poor sense of smell can be an early warning sign of neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease, as well as a mortality risk,” said Vidya Kamath of Johns Hopkins University School of Medicine.
“This study underscores its association with depressive symptoms. Additionally, this study explores factors that might influence the relationship between olfaction and depression, including poor cognition and inflammation.”
The research relied on data collected from 2,125 individuals in the Health, Aging, and Body Composition Study (Health ABC), a federal government study. This participant pool was comprised of healthy older adults between the ages of 70 and 73 when the eight-year-long study period began from 1997 to 1998.
The participants did not have any difficulty climbing 10 steps, walking 0.25 miles, or completing typical activities at the onset of the research. Then, they were assessed by phone every six months and in person every year.
These assessments focused on mobility tests, depression, and the ability to detect certain odors.
Sense of smell was first measured in 1999, at which point just under half of the participants– 48%– displayed a normal sense of smell. At the same time, 28% of the participants showed hyposmia, or a decreased sense of smell, and 24% showed anosmia or a significant loss of smell.
The participants who had better olfaction tended to be younger in age than the participants reporting significant smell loss or hyposmia. Throughout follow-up assessments, 25% of the study participants ultimately developed severe depressive symptoms.