Peanut butter can diagnose Alzheimer's disease

Health researchers at the University of Florida have found a quick and cheap way to test for early-stage Alzheimer’s disease. The only equipment necessary is a container of peanut butter and a ruler.

Graduate student Jennifer Stamps came up with the idea while she was working with Dr Kenneth Heilman, a professor of neurology and health psychology in the UF College of Medicine’s department of neurology. She noticed that the patients in Dr Heilman’s clinic were not tested for their sense of smell - often one of the first things to be affected in cognitive decline.

Stamps thought peanut butter would be ideal because it is a “pure odourant”, she said, that is only detected by the olfactory nerve and is easy to access. She and her colleagues conducted a small pilot study and the results were published in the Journal of the Neurological Sciences.

In the study, patients sat down with a clinician, 14 g of peanut butter and a 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. The clinician then moved the peanut butter up the ruler one centimetre at a time until the person could detect an odour. The distance was recorded and the procedure repeated on the other nostril.

The scientists found that patients in the early stages of Alzheimer’s disease had a dramatic difference in detecting odour between the left and right nostril. The mean distance for the right nostril was normal at 17.4 cm, but the left nostril was impaired and did not detect the smell until it was an average of 5.1 cm away. This is consistent with Alzheimer’s patients often having more degeneration in their left hemisphere than their right.

Patients with other kinds of dementia, meanwhile, had either no differences in odour detection between nostrils or the right nostril was worse at detecting odour than the left one. And of the 24 patients who had mild cognitive impairment, which sometimes signals Alzheimer’s disease but sometimes does not, 10 patients showed left nostril impairment and 14 patients did not.

The patients’ diagnoses were not usually confirmed until weeks after the clinical testing. By confirming diagnosis early, the researchers said this could “reduce disability, enhance quality of life and aid clinical trials”. Doctors could prescribe drugs to slow down the disease’s effects, and Stamps said treatment could be more aggressive to prevent the disease’s progression.

The test’s quick and cheap nature makes it suitable for clinics that don’t have the resources to run more elaborate tests. Stamps said the researchers also plan to see if the test could predict Alzheimer’s in patients with mild cognitive impairment.

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