Alzheimer's disease is difficult to diagnose before symptoms start showing up, because there is no single test that can definitively determine whether a person has the degenerative brain disease.
Could a scoop of peanut butter and a ruler become that elusive test?
That's what researchers at the University of Florida's McKnight Brain Institute Center for Smell and Taste are hoping. They found patients with early-stage Alzheimer's disease had more difficulty smelling peanut butter held at short distances from their nose than people without the disease.
"At the moment, we can use this test to confirm diagnosis," graduate student Jennifer Stamps, who led the research, said in a statement. "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."
About 5.2 million Americans have Alzheimer's or another form of dementia, according to the Alzheimer's Association, with about 13.8 million cases expected by 2050. The disease is marked by declines in cognitive function and memory skills, and people aren't typically diagnosed until they take mental status exams or doctors rule out other diseases that cause dementia-like symptoms.
Stamps was under the tutelage of Dr. Kenneth Heilman, a distinguished professor of neurology, when she noticed his patients had not been tested for their sense of smell. According to the graduate student's research, the ability to smell is associated with the first cranial nerve -- a set of nerves on the brain's surface -- called the "olfactory nerve." The olfactory nerve is often one of the first things to be affected in cognitive decline, even before memory loss, she pointed out.
"Dr. Heilman said, 'If you can come up with something quick and inexpensive, we can do it,'" she said.
For the study, researchers took a tablespoon of peanut butter and a metric ruler, and asked more than 90 people with either mild cognitive impairment, Alzheimer's, other forms of dementia or no neurological problems, to close their eyes and mouth, and block one nostril. The researchers then moved a peanut butter container one centimeter at a time up the ruler until the patient could detect the odor. The experiment was repeated again 90 seconds later with the other nostril.
The researchers were blinded to whether subjects had already been diagnosed with early stage Alzheimer's.
Mild cognitive impairment (MCI) is a condition that's characterized by memory loss and cognitive declines beyond what's expected from normal aging, but the declines don't impact daily functioning unlike dementia, according to the University of California, San Francisco Memory and Aging Center. Not everyone with MCI will go on to develop Alzheimer's, though they are at an increased risk. But at this time, doctors can't tell who with MCI will go on to develop Alzheimer's.
The study showed all 18 patients with early-stage Alzheimer's had trouble smelling the peanut butter with their left nostril until it was an average of 10 centimeters closer to their nose than their test with the right nostril. Patients at the clinic who had other forms of non-Alzheimer's dementia did not show this discrepancy in smelling ability, or had a worse right nostril than the left.
Of the 24 patients with MCI, 10 had left nostril impairment and 14 did not, which suggests the former group might go on to develop Alzheimer's. The researchers warned more studies are needed to fully understand the implications.
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But, the University of Florida plans to add the peanut butter test to its arsenal to help distinguish Alzheimer's from other memory disorders, according to the statement.
"If we can catch it at that earlier stage, we can start treatment more aggressively at that earlier stage, and you can prevent a lot of the progression," added Stamps in a YouTube video explaining her study.
The pilot study was published in a recent issue of the Journal of Neurological Sciences.
This isn't the only recent attempt at finding a cheap test to predict early dementia.
Northwestern University researchers reported in August that testing subjects with 20 black and white pictures of famous people including John F. Kennedy and Bill Clinton may provide clues into dementia risk. People with early-onset dementia, as confirmed by loss of brain tissue seen on MRI scans, scored an average of 79 percent on the test when people without dementia scored nearly 100 percent.