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A reduced sense of smell has long been associated with dementia and mortality risk in older adults. A new study has found evidence that it may also be linked to late-life depression.

Participants included more than 2,000 older adults aged 71 to 82 years who completed an odor identification task during the third year of the Health, Aging and Body Composition study. Investigators analyzed the data from followup testing, including cognitive assessments, depressive symptoms and inflammatory markers over the following eight years.

People with relatively decreased olfaction (sense of smell) were more likely to develop significant depressive symptoms, with a 6% higher risk of being in the “stable moderate,” and “stable high” depression symptoms groups, compared with the “stable low” group, the researchers found. Poor cognitive status, but not inflammation, partially mediated the relationship between olfactory performance and incident depression symptom severity.

Although the results do not determine a causal relationship, they lend more evidence that sense of smell may be a measure of overall health and well-being, investigators said.

“Losing your sense of smell influences many aspects of our health and behavior … . Now we can see that it may also be an important vulnerability indicator of something in your health gone awry,” Vidya Kamath, PhD, of the Johns Hopkins University School of Medicine in Baltimore, said in a statement. “Smell is an important way to engage with the world around us, and this study shows it may be a warning sign for late-life depression.” 

Full findings were published in the Journals of Gerontology.

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