What do a dollop of peanut butter, a ruler and Alzheimer’s disease have in common? It turns out that the food and the measuring tool can be used to confirm a diagnosis of early stage Alzheimer’s disease.

Neurology patients do not currently routinely get tested for their sense of smell, which is associated with the first cranial nerve and is often one of the first things to be affected in cognitive decline. A University of Florida graduate student came up with the idea of using peanut butter to test this nerve.

In the study, 94 patients who came to the clinic for neurological testing also sat down with a clinician, a tablespoon of peanut butter and a metric ruler. The researchers measured how long it took the patients to smell the peanut butter and tracked how close to the nose it was when they did.

The clinicians running the test did not know the patients’ diagnoses, which were not usually confirmed until weeks after the initial clinical testing.

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 right nostril proved to be more sensitive to sniffing out the scent. On average, the peanut butter had to be about 10 centimeters closer to the nose before the left nostril could detect it in patients with Alzheimer’s disease. Interestingly, this was not the case in patients with other kinds of dementia; these patients had either no differences in odor detection between nostrils or the right nostril was worse at detecting odor than the left one.

The researchers say more studies are needed to determine if peanut butter can truly help diagnose patients with Alzheimer’s disease. In the meantime, spread that peanut butter on a sandwich and enjoy it.