# The peanut butter test for Alzheimer's **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [October 11, 2013, 9:52pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025 "2013-10-11T21:52:31Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![deltasigma](https://avatars.discourse-cdn.com/v4/letter/d/e5b9ba/32.png) [@deltasigma](https://boards.straightdope.com/u/deltasigma)\ **Post date:** [October 11, 2013, 9:52pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/1 "2013-10-11T21:52:31Z")
This sounds like a joke, but it’s hard science. [Video interview with researchers at link](http://news.ufl.edu/2013/10/08/alzheimers-test/). > [@](#): > > GAINESVILLE, Fla. — A dollop of peanut butter and a ruler can be used to confirm a diagnosis of early stage Alzheimer’s disease, [University of Florida](http://www.ufl.edu) Health researchers have found. . . . > . > > . > > . > In the study, patients who were coming to the clinic for testing also sat down with a clinician, 14 grams of peanut butter — which equals about one tablespoon — and a metric 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 centimeter at a time during the patient’s exhale until the person could detect an odor. The distance was recorded and the procedure repeated on the other nostril after a 90-second delay. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [October 11, 2013, 9:56pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/2 "2013-10-11T21:56:26Z")
Doesn’t sound like hard science. The distance is going to depend quite a lot on stray air currents in the room. ---
**Author:** ![deltasigma](https://avatars.discourse-cdn.com/v4/letter/d/e5b9ba/32.png) [@deltasigma](https://boards.straightdope.com/u/deltasigma)\ **Post date:** [October 11, 2013, 9:57pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/3 "2013-10-11T21:57:21Z")
edit function not working. > [@](#): > > 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 left nostril was impaired and did not detect the smell until it was an average of 10 centimeters closer to the nose than the right nostril had made the detection in patients with Alzheimer’s disease. This was not the case in patients with other kinds of dementia; instead, these patients had either no differences in odor detection between nostrils or the right nostril was worse at detecting odor than the left one. ---
**Author:** ![deltasigma](https://avatars.discourse-cdn.com/v4/letter/d/e5b9ba/32.png) [@deltasigma](https://boards.straightdope.com/u/deltasigma)\ **Post date:** [October 11, 2013, 10:00pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/4 "2013-10-11T22:00:08Z")
> [@Napier](#): > > Doesn’t sound like hard science. The distance is going to depend quite a lot on stray air currents in the room. That will probably be an issue for implementing the test in other venues but I’m sure the researchers were smart enough to take this into consideration. You might want to read the whole article. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [October 11, 2013, 10:44pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/5 "2013-10-11T22:44:38Z")
It seems to me that there would be all sorts of confounds with a test like this. Never mind air currents, what if someone had a bit of snot lodged in one nostril but not the other? Does the test work the same for left handed as for right handed people, I wonder, or is it reversed? (Given the complications of left-handedness, one might expect it to be reversed in some but not others.) Also, at least going by the article at your link, it seems as though they have absolutely no idea why the nostrils actually should be differentially affected by Alzheimer’s, which makes it all a bit dubious. ---
**Author:** ![nearwildheaven](https://avatars.discourse-cdn.com/v4/letter/n/90db22/32.png) [@nearwildheaven](https://boards.straightdope.com/u/nearwildheaven)\ **Post date:** [October 11, 2013, 10:50pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/6 "2013-10-11T22:50:36Z")
There’s a “smell identification test” for Alzheimer’s. People are asked to identify about a dozen common scents, and while it’s not definitive (only a brain biopsy is), it’s apparently quite accurate. This, of course, only works for people who still have their sense of smell. ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [October 11, 2013, 10:51pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/7 "2013-10-11T22:51:51Z")
> [@njtt](#): > > Also, at least going by the article at your link, it seems as though they have absolutely no idea why the nostrils actually should be differentially affected by Alzheimer’s, which makes it all a bit dubious. You don’t have to know _why_ a correlation exists to prove that it exists. Doesn’t each nostril go to a different hemisphere of the brain, like your eyes and ears? I believe it’s well known that Alzheimer’s is correlated with problems in the corpus callosum. ---
**Author:** ![deltasigma](https://avatars.discourse-cdn.com/v4/letter/d/e5b9ba/32.png) [@deltasigma](https://boards.straightdope.com/u/deltasigma)\ **Post date:** [October 11, 2013, 10:54pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/8 "2013-10-11T22:54:43Z")
> [@njtt](#): > > It seems to me that there would be all sorts of confounds with a test like this. Never mind air currents, what if someone had a bit of snot lodged in one nostril but not the other? Does the test work the same for left handed as for right handed people, I wonder, or is it reversed? (Given the complications of left-handedness, one might expect it to be reversed in some but not others.) Also, at least going by the article at your link, it seems as though they have absolutely no idea why the nostrils actually should be differentially affected by Alzheimer’s, which makes it all a bit dubious. The article DOES indicate that this is in the early stages of testing but I think you have to admit that this seems to be a very promising test for a disease that is notoriously difficult to diagnose in the early stages. Or would you prefer to just ignore this and have doctors continue to bumble along, never knowing who has mild cognitive impairment vs early stage Alzheimer’s? ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [October 11, 2013, 10:56pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/9 "2013-10-11T22:56:45Z")
Also, what the hell is meant by > [@](#): > > peanut butter … is a “pure odorant” that is only detected by the olfactory nerve ? Under the circumstances, how on Earth is anything, whether it be peanut butter, or rose oil, or gasoline, or whatever, going to be detected other than via the olfactory nerve? Maybe there really is a good reason why peanut butter is the ideal test odorant, but the explanation given seems like gobbledegook, and makes me suspicious about the whole thing. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [October 11, 2013, 11:04pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/10 "2013-10-11T23:04:47Z")
> [@deltasigma](#): > > The article DOES indicate that this is in the early stages of testing but I think you have to admit that this seems to be a very promising test for a disease that is notoriously difficult to diagnose in the early stages. Or would you prefer to just ignore this and have doctors continue to bumble along, never knowing who has mild cognitive impairment vs early stage Alzheimer’s? No, I don’t think it sounds “very promising”. That is my point. It would be nice if it works, and it may be worth following up further, but I will be surprised if it really pans out. If it is real, possibly the most significant aspect of it is not the ‘test’, but the discovery (if it is one) that Alzheimer’s differentially affects the left and right parts of the olfactory system. This looks to me like a typical bit of bad science journalism (og knows, there is plenty of it about), reporting prematurely on a half-baked scientific idea. ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [October 11, 2013, 11:09pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/11 "2013-10-11T23:09:14Z")
> [@njtt](#): > > Under the circumstances, how on Earth is anything, whether it be peanut butter, or rose oil, or gasoline, or whatever, going to be detected other than via the olfactory nerve? Maybe there really is a good reason why peanut butter is the ideal test odorant, but the explanation given seems like gobbledegook, and makes me suspicious about the whole thing. I just did some looking online and it appears possible there’s some science behind this statement. Many substances have mixed odors and as a result, the nerve signals for smelling these substances travel along several different nerve paths simultaneously. You think you’re smelling one smell but you’re actually smelling a combination of different smells and your brain reassembles all of them into a single smell. Pure odorants are the term for substances where the nerve signals for the smell passes along a single nervous path. In a test like this, where they’re looking to see how quickly the substance is detected, they’d want a single nerve path so there’s no confusion. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [October 11, 2013, 11:14pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/12 "2013-10-11T23:14:00Z")
> [@friedo](#): > > You don’t have to know _why_ a correlation exists to prove that it exists. True, but if you have an explanation for it, that makes it a lot more plausible that it is a real effect, rather than the spurious result of some statistical artifact or experimental error. > [@friedo](#): > > Doesn’t each nostril go to a different hemisphere of the brain, like your eyes and ears? I believe it’s well known that Alzheimer’s is correlated with problems in the corpus callosum. Yeah, but none of that explains why the left and right nostrils would be differentially affected in a systematic way. There is an olfactory bulb (where olfactory information gets processed) on each side of the brain, and AFAIK the lesions causing Alzheimer’s symptoms occur at pretty much random places throughout the brain. ---
**Author:** ![deltasigma](https://avatars.discourse-cdn.com/v4/letter/d/e5b9ba/32.png) [@deltasigma](https://boards.straightdope.com/u/deltasigma)\ **Post date:** [October 11, 2013, 11:17pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/13 "2013-10-11T23:17:45Z")
> [@njtt](#): > > No, I don’t think it sounds “very promising”. That is my point. It would be nice if it works, and it may be worth following up further, but I will be surprised if it really pans out. If it is real, possibly the most significant aspect of it is not the ‘test’, but the discovery (if it is one) that Alzheimer’s differentially affects the left and right parts of the olfactory system. > > This looks to me like a typical bit of bad science journalism (og knows, there is plenty of it about), reporting prematurely on a half-baked scientific idea. I’m sure they will take your expert opinion under advisement. ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [October 11, 2013, 11:23pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/14 "2013-10-11T23:23:39Z")
> [@Little\_Nemo](#): > > I just did some looking online and it appears possible there’s some science behind this statement. Many substances have mixed odors and as a result, the nerve signals for smelling these substances travel along several different nerve paths simultaneously. You think you’re smelling one smell but you’re actually smelling a combination of different smells and your brain reassembles all of them into a single smell. > > Pure odorants are the term for substances where the nerve signals for the smell passes along a single nervous path. In a test like this, where they’re looking to see how quickly the substance is detected, they’d want a single nerve path so there’s no confusion. Well ok, “pure odorant” may mean something (though peanut butter? that is a ‘basic’ odor? really?:eek:) but why is such purity relevant to testing which nostril is more affected? Is it just the peanut-butter-smell dedicated fibres in the olfactory nerve that are differentially affected on either side? ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [October 11, 2013, 11:26pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/15 "2013-10-11T23:26:16Z")
> [@deltasigma](#): > > I’m sure they will take your expert opinion under advisement. Yours too, darling. ---
**Author:** ![Canadjun](https://avatars.discourse-cdn.com/v4/letter/c/76d3ee/32.png) [@Canadjun](https://boards.straightdope.com/u/Canadjun)\ **Post date:** [October 11, 2013, 11:26pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/16 "2013-10-11T23:26:46Z")
What about people (like me) that just have a **very** crappy sense of smell? ---
**Author:** ![suranyi](https://avatars.discourse-cdn.com/v4/letter/s/e36b37/32.png) [@suranyi](https://boards.straightdope.com/u/suranyi)\ **Post date:** [October 11, 2013, 11:55pm UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/17 "2013-10-11T23:55:13Z")
> [@njtt](#): > > True, but if you have an explanation for it, that makes it a lot more plausible that it is a real effect, rather than the spurious result of some statistical artifact or experimental error. I suppose, but you know that a lot of scientific discovery has occurred when unexpected correlations were observed, and only much later were explanations found. As Isaac Asimov said, “The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka!’ but ‘That’s funny…’” ---
**Author:** ![bibliophage](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bibliophage/32/7615_2.png) [@bibliophage](https://boards.straightdope.com/u/bibliophage)\ **Post date:** [October 12, 2013, 1:18am UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/18 "2013-10-12T01:18:16Z")
> [@njtt](#): > > Also, what the hell is meant by ? > Under the circumstances, how on Earth is anything, whether it be peanut butter, or rose oil, or gasoline, or whatever, going to be detected other than via the olfactory nerve? It’s not explained well in the article, but I suspect they’re referring to things that don’t stimulate the receptors in the nasal cavity innervated by the trigeminal nerve. These receptors respond to what is sometimes called “pungency”: things like chili peppers, mustard, and horseradish, all of which can also stimulate true odor receptors innervated by the olfactory nerve. I believe the cold receptors that respond to menthol and give peppermint a cool perception are also innervated by the trigeminal nerve. Something like mustard that stimulates both pathways could well muck up the results, so they chose to use one of the many substances that stimulates only the true odor receptors innervated only by the olfactory nerve. That is not the same as saying that there is one and only one type of odor receptor that responds to the odor of PB and nothing else. At least that’s my reading of what they’re trying to say. ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [October 12, 2013, 1:24am UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/19 "2013-10-12T01:24:45Z")
> [@njtt](#): > > Well ok, “pure odorant” may mean something (though peanut butter? that is a ‘basic’ odor? really?:eek:) but why is such purity relevant to testing which nostril is more affected? Is it just the peanut-butter-smell dedicated fibres in the olfactory nerve that are differentially affected on either side? Apparently (from what I found) different odors trigger different parts of the brain’s olfactory area. So a mixed scent might trigger a response in different areas. A pure odorant, like peanut butter, would presumably only trigger one area. This may be the basis for why there’s a difference in the response of the right and left nostrils. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [October 12, 2013, 2:50am UTC](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025/20 "2013-10-12T02:50:26Z")
> [@deltasigma](#): > > That will probably be an issue for implementing the test in other venues but I’m sure the researchers were smart enough to take this into consideration. You might want to read the whole article. You’re right, I should have read the whole article. But when I did, I didn’t see anything in the article that fixes this question. Though, it’s a pleasant article more or less advertising the school, it’s not a scientific paper. As pleasant articles go it seems competent enough. This would be in the category of medical research, not for example fluid dynamics research. If holding things different distances from the nose is already an established test method with various problems worked out and good practices well known, it’s probably fine. But if the cleverness of a simple smelling distance test is novel here, I wonder how room air currents get accounted for. No doubt we all have the experience of people near one another, one of whom smells something strongly while the other doesn’t. [Next page](https://boards.straightdope.com/t/the-peanut-butter-test-for-alzheimers/671025.md?page=2)