Research gets nutty

UF researchers find that ‘peanut butter’ test can help diagnose Alzheimer’s disease

By Melissa Lutz Blouin

A dollop of peanut butter and a ruler can be used to confirm a diagnosis of early stage Alzheimer’s disease, UF Health researchers have found. Jennifer Stamps, a graduate student in UF’s Evelyn F. and William L. McKnight Brain Institute Center for Smell and Taste, came up with the idea of using peanut butter to test for smell sensitivity when she noticed patients were not being tested for their ability to smell, which is often one of the first things to be affected in cognitive decline.

Stamps came to this realization while shadowing Kenneth Heilman, M.D., the James E. Rooks distinguished professor of neurology and health psychology in the UF College of Medicine’s department of neurology.

“Dr. Heilman said, ‘If you can come up with something quick and inexpensive, we can do it,’” Stamps said.

Stamps conducted a small pilot study using peanut butter and published the findings in the Journal of the Neurological Sciences. She said she thought of peanut butter because it is a “pure odorant” that is only detected by the olfactory nerve and is easy to access. In the study, the patient closed his or her eyes and mouth and blocked one nostril. The clinician opened the peanut butter container and held a ruler next to the open nostril while the patient breathed normally. The clinician then moved the peanut butter up the ruler one centimeter at a time until the person could detect an odor. The distance was recorded and the procedure repeated on the other nostril after a 90-second delay.

Researchers found patients in the early stages of Alzheimer’s disease had a dramatic difference in detecting odor between the left and right nostril. The left nostril was impaired and did not detect the smell until it was an average of 10 centimeters closer to the nose than the right nostril. Patients with other kinds of dementia, however, had either no differences in odor detection between nostrils or the right nostril was worse at detecting odor than the left one.

Of the 24 patients tested who had mild cognitive impairment, which sometimes signals Alzheimer’s disease and sometimes turns out to be something else, about 10 patients showed left nostril impairment. The researchers said more studies must be conducted to fully understand the implications.

“At the moment, we can use this test to confirm diagnosis,” Stamps said. “But we plan to study patients with mild cognitive impairment to see if this test might be used to predict which patients are going to get Alzheimer’s disease.” Many tests to confirm a diagnosis of Alzheimer’s disease or other dementias can be time-consuming, costly or invasive. Heilman said this test could be used by clinics that lack access to the personnel or equipment to run other, more elaborate tests. “We see people with all kinds of memory disorders,” Heilman said. “This can become an important part of the evaluation process.”