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Why You Should Worry If You Can’t Smell Peanut Butter

And now for the world’s most unlikely scientific discovery: Researchers have found that they can diagnose early Alzheimer’s disease with nothing more than a tablespoon of peanut butter and a ruler.

And now for the world's most unlikely scientific discovery: Researchers have found that they can diagnose early Alzheimer's disease with nothing more than a tablespoon of peanut butter and a ruler.

Alzheimer's, as we are sure you know, is a terrible, debilitating disease, and is becoming more common in recent times: The Alzheimer's Association says that currently, one American develops Alzheimer's every 68 seconds. And here's the great news for those of us in our twenties now—they expect this figure rise to one American every 33 seconds by 2050.


So, diagnosing the disease in its early stages—when aggressive treatment may slow down much of the incurable disease's progression—is important. And if that early detection can be done inexpensively and easily, well, that would be great news, wouldn't it?

RECIPE: Gluten-Free Salted Peanut Butter Cookies

Medical News Today reports that Jennifer Stamps is the brain behind the new study. As a mere grad student at the University of Florida, she had a very good idea. She knew that the ability to smell is associated with the first cranial nerve, and the first cranial nerve is one of the first things to go when a person's cognition begins to decline. She reasoned that if she took a "pure odorant"—i.e., something that is only detected by the olfactory nerve and is easy to assess—and tested subjects for their ability to smell it, she might find that those who didn't do well on the test would also show evidence of cognitive deficit.

Working with Dr. Kenneth Heilman, an esteemed behavioral neurologist from UF's College of Medicine, Stamps asked subjects to close their eyes and mouth and block one nostril. She then opened a peanut butter container and held a ruler next to the subject's open nostril. Moving the peanut butter up the ruler 1 centimeter at a time, the subjects were asked to say when they smelled the peanut butter. A measurement of the distance of the container to the nostril was taken. Ninety seconds later, the procedure was repeated on the other side.


Oddly enough, this is what the scientists found: Patients in the early stages of Alzheimer's disease had a pretty dramatic difference in their ability to detect odor between their two nostrils. In those with Alzheimer's the left nostril was impaired—it didn't smell the peanut butter until the stuff was, on average, ten centimeters closer to the nose than when the test was repeated on the right side.

Even weirder? This wasn't the result for patients who had other kinds of dementia.

As usual, the researchers said more studies were needed to fully understand the implications of their findings. As Stamps puts it, "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."

As an inexpensive test that reveals early-onset disease, this peanut butter test could be really useful. Heilman says, "This can become an important part of the evaluation process." The researchers are clearly excited: "If we can catch [Alzheimer's] at [an] early stage, we can start treatment more aggressively at the early stage and you can possibly prevent a lot of the progression."

So doctors: but yourself some peanut butter for the office. You can use it to test people for Alzheimer's—and then you can spread it on a sandwich.