Could a Simple Smell Test Help Spot Alzheimer's Early?
Study found weakened sense of smell associated with dementia risk, but more research needed
Participants received brain scans, genetic testing, blood and spinal fluid tests, and PET scans to detect amyloid plaques in the temporal lobe, an area important for memory. They also took a smell identification test known as the University of Pennsylvania Smell Identification Test (UPSIT) and a comprehensive set of tests to measure thinking skills.
"This research shows that the UPSIT/odor identification testing could theoretically be an affordable and quick screening test that could be followed up by more expensive, involved and accurate tests such as PET scans or cerebral spinal fluid studies," Growdon said.
The second study, led by Dr. Davangere Devanand, a professor of psychiatry and neurology at Columbia University Medical Center in New York City, found that among 757 participants, lower scores on the UPSIT smell test were associated with the transition to dementia and Alzheimer's disease.
Authors of both studies cautioned that their results were simply a snapshot in time, and larger studies that follow people over a longer period of time would be necessary to confirm the findings.
Dr. Kenneth Heilman, a professor in the department of neurology at the University of Florida College of Medicine in Gainesville, cautioned that many conditions can interfere with the sense of smell, including unclear nasal passages, allergies, nasal septum (nose structure) defects, Parkinson's disease, exposure to fumes and toxins, some medications and even aging itself.
"A loss of sense of smell does not mean you have Alzheimer's disease," said Heilman. "But if someone has episodic memory loss and also has a loss of smell, a degenerative disease like Parkinson's or Alzheimer's is a possibility."
Episodic memory loss is related to very recent memories, such as being able to recall what you had for dinner the night before, he explained.
Heilman estimates that about 12 percent of those with mild cognitive impairment (problems with memory, language, thinking and judgment that are greater than normal age-related changes) go on to develop Alzheimer's.
"We would love to know if the smell test would predict Alzheimer's," he said. "But we don't know how the test would work on a larger population."
For now, Heilman has a simple recommendation: "If you have a memory problem, see your doctor."