A dollop of peanut butter and a ruler can be used to confirm a diagnosis of early stage Alzheimer’s disease, University of Florida Health researchers found. Jennifer Stamps, a graduate student in the University of Florida (UF) McKnight Brain Institute Center for Smell and Taste, and her colleagues reported the findings of a small pilot study in the Journal of the Neurological Sciences in October 2013. Stamps came up with the idea of using peanut butter to test for smell sensitivity while she was working with Dr. Kenneth Heilman, one of the world’s best known behavioral neurologists, from the UF College of Medicine’s department of neurology. While shadowing doctors in Heilman’s clinic, she noticed that patients were not tested for their sense of smell. The ability to smell is associated with the first cranial nerve and is often one of the first things to be affected in cognitive decline. “Dr. Heilman said, ‘If you can come up with something quick and inexpensive, we can do it,'” Stamps says. She thought of peanut butter because, she said, it is a “pure odorant” that is only detected by the olfactory nerve and is easy to access.

Widespread problem According to the Alzheimer’s Association, Alzheimer’s disease affects 5.2 million people in the US and will cost the nation $203 billion in this year alone. Share on Pinterest Researchers found that by placing a dollop of peanut butter on a ruler, they could identify early stages of Alzheimer’s disease, based on patients’ ability to detect the odor at certain distances. The Association estimates that one American develops Alzheimer’s every 68 seconds, and they expect to see this figure rise to one American every 33 seconds by 2050. In the study, patients who were coming to the clinic for testing also sat down with a clinician, who was armed with 14 grams of peanut butter – which equals about 1 tablespoon – and a metric ruler. The patient closed his or her eyes and mouth and blocked one nostril. The clinician opened the peanut butter container and held the ruler next to the open nostril while the patient breathed normally. By moving the peanut butter up the ruler 1 cm at a time during the patient’s exhalation, they were able to measure the distance at which the patient could detect the odor. The distance was recorded and the procedure repeated on the other nostril after a 90-second delay. The clinicians running the test did not know the patients’ diagnoses, which were not usually confirmed until weeks after the initial clinical testing.

Sense of smell loss The scientists found that 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 cm closer to the nose than the right nostril had made the detection in patients with Alzheimer’s disease. This was not the case in patients with other kinds of dementia; instead, these patients 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 a left nostril impairment and 14 patients did not. The researchers said more studies must be conducted to fully understand the implications. Stamps explains: “At the moment, we can use this test to confirm diagnosis. 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.” Stamps and Dr. Heilman point out that this test could be used by clinics that do not have access to the personnel or equipment to run other, more elaborate tests required for a specific diagnosis, which can lead to targeted treatment. At UF Health, the peanut butter test will be one more tool to add to a full suite of clinical tests for neurological function in patients with memory disorders.