• Posted March 27, 2025

Scent Test Can Sniff Out Cognitive Decline

The nose might know whether a person is showing early signs of dementia or Alzheimer’s disease, a new study says.

Older adults who’ve developed mild cognitive impairment -- a precursor to dementia and Alzheimer’s -- score lower on a peel-and-sniff test than people with normal brains, according to findings published March 24 in the journal Scientific Reports.

This sort of test can be taken at home to provide an early red flag for future declines in brain function, researchers say.

“Our goal has been to develop and validate a cost-effective, non-invasive test that can be performed at home, helping to set the stage for advancing research and treatment for Alzheimer’s,” senior researcher Dr. Mark Albers, a neurologist at Massachusetts General Hospital in Boston, said in a news release.

“Early detection of cognitive impairment could help us identify people who are at risk of Alzheimer’s disease and intervene years before memory symptoms begin,” Albers added.

In the test, participants sniff odor labels that have been placed on a card to assess their ability to identify, remember and discriminate between different scents.

People sample each odor, and then name the odor from a set of four options. Questions follow about how sure they are of their selection.

Overall, the ability to identify and remember odors declines with age, researchers found in administering their test to a group of 127 people with healthy brains.

But a small group of 19 people diagnosed with mild cognitive impairment scored even lower on the smell test than seniors with intact brain function, results show.

The test results were similar across English and Spanish speakers, and participants successfully performed the test whether or not they were helped by a research assistant, researchers found.

“Our results suggest that olfactory testing could be used in clinical research settings in different languages and among older adults to predict neurodegenerative disease and development of clinical symptoms,” Albers said.

However, more study is needed to further validate the test, and to see how it might fit in with other cognitive testing for dementia and Alzheimer’s, researchers noted.

More information

The Alzheimer’s Association has more on diagnosing Alzheimer’s.

SOURCE: Mass General Brigham, news release, March 24, 2025