How a Peanut Butter Test May Detect Alzheimer’s

Simple sniff test could change Alzheimer’s research

October 29, 2015 / By Brain & Spine Team

Peanut butter. Creamy or crunchy – and oh, so spreadable – but not exactly your first thought as a game changer in Alzheimer’s research.

But it may well be, according to researchers at the University of Florida who conducted the peanut butter smell test hoping to find a relationship between loss of smell and the detection of early-stage Alzheimer’s.

They were able to use the test to confirm an Alzheimer’s diagnosis. But they would like to be able to predict which patients are going to get Alzheimer’s disease.

Peanut butter smell test: the lowdown

So what exactly does a peanut butter smell test consist of?

1. Each person begins with closed eyes and mouth and they even close up one of their nostrils.
2. A researcher opens a jar of peanut butter and stands a good distance from each person, coming closer to the person until he or she can smell the peanut butter.
3. The researcher measures this distance.
4. The process is repeated using the other nostril after a 90-second break.
5. During testing, the research group is not aware of which people in the study had been diagnosed with Alzheimer’s.

What researchers found is peculiar. The sense of smell in the left nostril specifically was severely impaired in the tested group who already had early-stage Alzheimer’s.

In order for people to smell the peanut butter through their left nostril, the container had to be an average of 10 centimeters closer to the nose than for the right nostril.

“This is a significant part of this study,” says Dylan Wint, MD, who works in the Cleveland Clinic Lou Ruvo Center for Brain Health.

“There is a lot of research showing Alzheimer-related brain shrinkage starting on the left side of the brain, which is where the temporal lobe degenerates first.”

Ongoing research needed

The research showing a difference in the ability to smell peanut butter with each nostril was published in the Journal of the Neurological Sciences in 2013.

However, a follow-up study in 2014 conducted by researchers at the University of Pennsylvania was not able to replicate the earlier findings. In testing 15 patients with Alzheimer’s disease, they found no difference in the ability to detect the peanut butter smell in the left and right nostrils.

“This highlights the scientific importance of studies being repeated and refined by other researchers in different patient populations,” Dr. Wint says.

Research continues, with a plan to study patients with mild cognitive impairment.

Cheap, accurate testing

Cheap tests that are accurate and accessible can inform more patients about their Alzheimer’s status – and it can lead to better research of the disease, Dr. Wint says.

Currently, the most accurate early-stage diagnostic tests for Alzheimer’s involve a spinal tap or an amyloid PET scan. However, these tests are expensive, uncomfortable and not available everywhere.

“The accessibility of current Alzheimer’s tests is one of the issues that is making diagnosis and research difficult,” says Dr. Wint. “The amyloid PET scan can cost $5,000 and that is just to figure out who should be studied in any Alzheimer’s study for early-stage diagnosis,” he says.

Dr. Wint adds that the importance of diagnosing early-stage Alzheimer’s is that it is critical to finding treatments that delay or prevent future memory loss.