Rapid loss of smell predicts dementia and smaller brain areas linked to Alzheimer’s

Though we often undervalue our ability to smell compared to our abilities to see and hear, our olfactory sense provides our brain with critical information, from detecting potential dangers like smoke to recognizing the sweet smell of baking cookies.

Researchers at the University of Chicago Medicine have discovered another reason to appreciate our sniffers. Not only can a decline in a person’s sense of smell over time predict their loss of cognitive function, it can foretell structural changes in regions of the brain important in Alzheimer’s disease and dementia.

The findings, based on a longitudinal study of 515 older adults published July 2 in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, could lead to the development of smell-test screening to detect cognitive impairment earlier in patients.

“This study provides another clue to how a rapid decline in the sense of smell is a really good indicator of what’s going to end up structurally occurring in specific regions of the brain,” said senior author Jayant M. Pinto, MD, a professor of surgery at the University of Chicago and ENT specialist who studies olfactory and sinus disease.

It’s estimated more than 6 million Americans have Alzheimer’s disease, which is characterized by memory loss and other symptoms, such as mood changes and trouble completing everyday tasks. There is no cure for Alzheimer’s, but some medications can temporarily slow its symptoms.

Memory plays a critical role in our ability to recognize smells, and researchers have long known of a link between the sense of smell and dementia. The plaques and tangles that characterize tissue affected by Alzheimer’s disease often appear in olfactory and memory- associated areas before developing in other parts of the brain. It’s still unknown if this damage actually causes the decline in a person’s sense of smell.

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