Losing your sense of smell is thought to be one of the first signs of the disease.
So, at the University of Florida, they're using peanut butter to test a person's sensitivity.
After someone closes their eyes, researchers measure how close a tablespoon of peanut butter has to be for the person to smell it.
All of the Alzheimer's patients smelled normally through their right nostril, but had a big impairment in their left.
Early detection of Alzheimer's gives doctors a chance to slow it down.
"If we can catch it at that earlier stage, we can start treatment more aggressively at that earlier stage and you prevent a lot of the progression," said Jennifer Stamps of the University of Florida.
Meanwhile, researchers in England say a drug given to mice was able to stop the progression of a disease like Alzheimer's.
