Update 7/20/19. According to the Alzheimer's foundation, there are over 5 million Americans living with Alzheimer's disease. This could go as high as 16 million by 2050. While heart disease rates are dropping, death rates from Alzheimer's are up 89% since 2000. That's pretty scary but what if there was a way to know your risk before symptoms become apparent? Is it possible the test for Alzheimer's might be in your kitchen right now? Research has suggested the inability to smell peanut butter may be a way to predict if you will get Alzheimer's disease in the future. In this review, I will look at that research and try to make sense of it. Let's see what we can discover…
Peanut Butter Alzheimer's Research
So is there any evidence for this peanut butter smell test? Well, it does seem that one of the first signs of Alzheimer's is changes in our sense of smell. Might this mean Alzheimer's disease is caused by inhaling some kind of toxin? Maybe. Sometimes this is called the “olfactory vector hypothesis” of dementia and Parkinson's diseases.
In 2013, researchers in Florida published an interesting paper called A brief olfactory test for Alzheimer‘s disease. In this investigation, older adults –some with Alzheimer’s and some without – were instructed to close their eyes and mouth and breath normally as the researchers brought peanut butter closer and closer to their noses. They used a ruler to measure distance. They didn't use much peanut butter, only 14 grams which is 1/2 ounce.
Here's what they found:
People who did not have Alzheimer’s could smell the peanut butter –in both nostrils – when it was about 7 inches away from them.
But, here's what happened in those with Alzheimer’s:
- They could also smell the peanut butter when it was about 7 inches away from their right nostril only.
- They couldn’t detect the peanut butter smell in their left nostril until it was 2 inches away!
In other words, they couldn’t smell the peanut butter in their left nostril until it was only 2 inches away from their left nostril.
This observation was seen in 100% of the people in the study who had Alzheimer's disease.
Remember, it may be Alzheimer's disease begins in the region of the brain that processes smell. One piece of evidence for this is the fact that the smelling center of the brain (olfactory cortex) of those with Alzheimer's has more damage on the left side than the right side. This may be responsible for the left nostril having less sensitivity to peanut butter smell than the right nostril.
In 2014, researchers in Philadelphia tried to replicate this study to see if they could find the same thing. After all, this is the best way to know if the study was valid. These researchers studied 15 older men and women who likely had Alzheimer's based on their symptoms.
They did the exact same thing as the previous study. They did nothing different.
Unfortunately, these researchers did not find the same outcomes. They saw no difference in left or right nostril in its ability to smell peanut butter. This caused them to state “no meaningful asymmetry in smell perception is apparent,” which is ‘s fancy talk for they couldn't find any difference between left and right nostrils to smell peanut butter.
What Kind of Peanut Butter?
So what kind of peanut butter did they use in these studies? Was it Skippy, Jiff or Peter Pan? Was it chunky or smooth or honey roasted? They don't say. They only say it was plain peanut butter. The original investigates only state “A container of 14g of peanut butter was opened….”
Since there are no commercially amiable 14 grams (half an ounce) containers of peanut butter in supermarkets, this says to me someone took a small amount of some brand and put it in a container to be used in the study.
Peanut Butter Smell Test: Yes or No?
So, what's the verdict? Can peanut butter predict Alzheimer's or not? Because these two studies had different outcomes, it's hard to know for sure which one is correct. I think we need at least another investigation – maybe two – to know for sure.
Even so, that doesn't mean you can't do this simple test right now. All you need is a little bit of peanut butter (1/2 oz) and a ruler. If you do notice a difference in which nostril can smell peanut butter, that doesn't mean the end of the world because we are not sure yet what all this means.
Of course, you should always follow this up with your own doctor to get her/his insights. Trust me; they are aware of this research.
Preserving Brain Function Now
Regardless of what you discover when you do the peanut butter smell test, it's important to know that research is now starting to show dementia – including Alzheimer's – can be slowed down -or even maybe halted -if we start living a better lifestyle now.
What does that mean?
One thing is regular aerobic exercise. Research suggests there is a relationship between heart health and brain health. What's good for the heart is also good for the brain. Aerobic exercise seems to have a protective effect on the brain.
There are many reasons. One of which is exercise causes the body to make more antioxidants like superoxide dismutase (SOD) which battle free radicals and reduce oxidative stress.
So if you are able to, start doing some type of aerobic exercise program at least 30 minutes a day up to 60 minutes a day. It does not have to be running or intense either. Anything you enjoy will work.
Can strength training help? Maybe but regardless of its effects on brain health, strength training helps keep muscles strong and combat sarcopenia (muscle loss as we get older). The stronger our muscles are, the less chance of us ending up in a nursing home – dementia or not.
Another thing is eating more fruits, vegetables, seeds, and beans seem to be important too. I know what you're thinking – you mean to become a vegan. I'm not saying that but if you want to, great. There is evidence for both vegetarian and Mediterranean eating plans as being brain-healthy.
The more colors you add to your diet the healthier you will be overall. Why? The colors are the antioxidants. They protect the plants and when we eat them, they protect us too!
So can peanut butter help predict who will get Alzheimer's? Let's see what future studies discover. No matter what happens if you take the peanut butter smell test -and fail it – the take-home message is there are things you can do right now to improve brain function and reduce the risk of dementia.