Peanut Butter Sniff Test Confirms Alzheimer’s Disease

A new study suggests that using peanut butter to test for smell sensitivity might be a way to confirm a diagnosis of early-stage Alzheimer’s disease (AD).

Researchers at the University of Florida (UF; Gainesville, USA) conducted a retrospective, case-control study involving 94 participants to assess a quick olfactory test to aid diagnose of AD. Participants with probable AD (18 subjects), mild cognitive impairment (MCI, 24 subjects), other causes of dementia (OD, 26 subjects) and matched controls (26 subjects) were tested, with closed eyes, for their ability to detect peanut butter, held at the bottom of a 30 cm ruler and moved up one cm at a time during the participants' exhale. Upon odor detection, the distance between the subject's nostril and the peanut butter container was measured.

The results showed a dramatic difference in the mean odor detection difference (in centimeters) between the left and right nostrils of patients in the early stages of AD. The left nostril was impaired and did not detect the smell until it was 12 centimeters closer to the nose than the right nostril. For the other groups, the difference between the left and right nostrils was much smaller; − 1.9 for MCI; +4.8 for OD; and no difference for the matched controls. The study was published in the October 15, 2013, issue of the Journal of the Neurological Sciences.

“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,” concluded lead author graduate student Jennifer Stamps, BSc, of the UF McKnight Brain Institute Center for Smell and Taste. “The test could be used by clinics that don’t have access to the personnel or equipment to run other, more elaborate tests required for a specific diagnosis, which can lead to targeted treatment.”

One of the first places in the brain to degenerate in people with AD is the front part of the temporal lobe that evolved from the smell system, which is also the portion of the brain is involved in forming new memories.

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