Peanut butter test may be key to Alzheimer's diagnosis

Published: Thursday, October 10, 2013 at 2:26 p.m.
Last Modified: Thursday, October 10, 2013 at 2:26 p.m.

Correction: The name of the researcher, Jennifer Stamps, was reported incorrectly in an earlier version of this article.

A little bit of peanut butter can go a long way — namely, in helping to diagnose Alzheimer's disease.

Jennifer Stamps, a University of Florida graduate student in neurology, was looking for a quick and easy way to test patients' cranial nerve I, also known as the smell nerve. So she came up with the peanut butter test, and the results of her small pilot study were recently published in the Journal of Neurological Sciences.

Stamps' advisor, Dr. Kenneth Heilman, a professor of neurology and health psychology, told her, "If you can come up with something quick, let's do it," Stamps recalled.

Stamps was surprised that smell was not part of a routine neurology exam, since many patients with cognitive disorders have an impaired sense of smell.

With Alzheimer's patients especially, "The original deterioration is in part of the smell brain," Heilman said, adding that other studies show a decreased sense of smell in these patients.

Stamps said she chose peanut butter because it is widely available, doesn't require refrigeration, and mostly because it's what's known as a "pure odorant," a substance that isn't detected by other nerves.

Alcohol and perfumes, for example, are considered irritants, Heilman explained, because they are detected by other nerves, which would detract from isolating the olfactory nerve.

"Peanut butter is only mediated by the (olfactory) nerve that goes (directly) to the nose," Heilman said.

Heilman and Stamps also know that Alzheimer's degeneration begins on the left side of the brain, so they devised a way of testing both the left and right nostrils. Using a regular metric ruler, they put a dollop of peanut butter on its end, and measured how far away the peanut butter could be in order for people to detect it.

"If they can smell it far away it means that nerve is working. If you have to bring it all the way up to the nose it means it's not working as well," Heilman said.

"We were blown away with what we saw," Stamps added. "The right nostril was normal, and the left had impairment" in Alzheimer's patients but none of the other patients.

"So far the test has been 100 percent accurate."

They confirmed an Alzheimer's diagnosis in 94 patients, but Stamps said it's not a reliable test for patients with other types of cognitive disorders.

"(The test) looks as if it's very promising. Like anything else, future studies from other labs have to replicate it," Heilman said, adding that they now hope to use the information to determine which memory disorder patients are most likely to develop Alzheimer's disease. In so doing, they could then give them medications to slow the onset of disease.

Heilman added that those medications are still in development, but in the meantime people can take the peanut butter test.

"There are all kinds of fancy smell tests that cost a fortune. The nice thing about this test … it's peanut butter and a ruler. Anybody can get it," he said.

Stamps cautioned against people doing the test at home, however. "I wouldn't suggest people do it at home for the fun of it … although if it gets you to the doctor, that's great," Stamps said, adding that her mother thought that the test sounded like fun, so she did it at "game night" with her friends.

One of her friend's parents had Alzheimer's, so when the friend couldn't smell the peanut butter with her left nostril, she panicked. The experience did get her to the doctor, Stamps said.

"I tell people unless they really want to know, don't do it," she said.

Contact Kristine Crane at 338-3119, or


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