Since sense of smell dramatically declines in the early stages of Alzheimer’s, administering a “sniff test” can more accurately diagnose the disease. Researchers at the University of Pennsylvania published a new study in the Journal of Alzheimer’s Disease that evaluated the test.

The test may also be useful for diagnosing mild cognitive impairment, which is a condition that often progresses to Alzheimer’s after a few years. The industry is working to find new ways to spot people at risk of Alzheimer’s but without symptoms because medications under development might not work after the disease sets in.

For the study, the researchers used the Sniffin’ Sticks Odor Identification Test, which required the participants to identify 16 different odors. They had 728 elderly participants undergo both the sniff test and the Montreal Cognitive Assessment, a standard cognitive test.

After being evaluated by physicians at the university, the participants were classified in one of three groups; healthy older adult, mild cognitive impairment, or Alzheimer’s dementia. The researchers used the results from the cognitive test alone or combined with the sniff test to determine how well they classified each group.

The cognitive test alone accurately classified 75 percent of those with MCI, but when the sniff test results were combined that rose to 87 percent. The combination of the two tests also helped them more accurately identify healthy older adults and those with Alzheimer’s dementia.

This downside to the sniff test is that it takes between five to eight minutes to complete. The researchers are working on shortening it to three minutes, with hopes that more neurology clinics will be interested in this type of screening.

The researchers are also planning to investigate whether protein markers of Alzheimer’s can be detected in nasal fluid. If it can be done, that would provide an even earlier warning sign of the disease process.

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