They found that those in the early stages of Alzheimer’s disease lose their sense of smell in the left nostril more quickly than in the right and peanut butter is the perfect substance with which to detect the problem.
... Researcher Jennifer Stamps at UF McKnight Brain Institute Center for Smell and Taste conducted the experiment by holding a ruler to the noses of patients with Alzheimer’s and other forms of dementia.
One nostril at a time, with the other one held shut, Stamps then slowly moved a tablespoon of peanut butter closer to the nostril in centimeter increments.
The patients signaled when they could smell the peanut butter.
What Stamps found is that Alzheimer’s patients, unlike those with other forms of dementia, had better smell in the right nostril than in the left.
On average, patients could smell the peanut butter at about 20 centimeters from their right nostril versus 10 centimeters from their left.