The ability to smell is associated with the first cranial nerve and is often the first one to be degraded in cognitive decline. Peanut butter is what you call a “pure odorant”, so it is only detected by the olfactory nerve and is very easy to access.
“Dr. Heilman said, ‘If you can come up with something quick and inexpensive, we can do it,’” Stamps says.
Basically, they asked patients to participate of this test, which only included a tablespoon and a ruler. The patient closed his or her eyes and mouth and blocked one nostril while the clinician opened the peanut butter container and placed it close to the open nostril. The clinician then moved the peanut butter 1 cm closer to the nostril and asked the patient if he/she felt the peanut butter smell, then repeated the entire procedure with the other nostril, after a 90 second period delay. People with early stages of Alzheimer’s had a dramatic difference between the left and right nostril performance – the left nostril was impaired, detecting the smell at an average of 10 cm closer.
In other types of dementia, the patients had almost no difference between the left and right nostril.
“At the moment, we can use this test to confirm diagnosis,” Stamps says. “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.”
This test could be incredibly useful especially in less developed areas of the world, where clinics don’t have access to the equipment necessary to conduct traditional tests.
“We see people with all kinds of memory disorders,” Heilman says. Many tests to confirm a diagnosis of Alzheimer’s disease or other dementias can be time-consuming, costly, or invasive. “This can become an important part of the evaluation process.”