Peanut Butter Smell Test Can Reveal Early Alzheimer'sWednesday, 09 Oct 2013
A spoonful of peanut butter and a ruler can be used to confirm a
diagnosis of early stage Alzheimer’s disease, according to
researchers at the
University of Florida's
McKnight Brain Institute Center for Smell and Taste.
Graduate student Jennifer Stamps came up with the idea of using
peanut butter to test for smell sensitivity while she was working
with Dr. Kenneth Heilman, the James E. Rooks distinguished professor
of neurology and health psychology in the UF College of Medicine’s
department of neurology.
She noticed while shadowing in Heilman’s clinic that patients were
not tested for their sense of smell. The ability to smell is
associated with the first cranial nerve and is often one of the
first things to be affected in cognitive decline. Stamps also had
been working in the laboratory of Linda Bartoshuk, the William P.
Bushnell presidentially endowed professor in the College of
Dentistry’s department of community dentistry and behavioral
sciences and director of human research in the Center for Smell and
Taste.
“Dr. Heilman said, ‘If you can come up with something quick and
inexpensive, we can do it,’” Stamps said.
ALERT: 5 Signs You’ll Get Alzheimer’s Disease
She thought of peanut butter because, she said, it is a “pure
odorant” that is only detected by the olfactory nerve and is easy to
access.
In the study, patients who were coming to the clinic for testing
also sat down with a clinician, 14 grams of peanut butter — which
equals about one tablespoon — and a metric ruler. The patient closed
his or her eyes and mouth and blocked one nostril. The clinician
opened the peanut butter container and held the ruler next to the
open nostril while the patient breathed normally. The clinician then
moved the peanut butter up the ruler one centimeter at a time during
the patient’s exhale until the person could detect an odor. The
distance was recorded and the procedure repeated on the other
nostril after a 90-second delay.
The clinicians running the test did not know the patients’
diagnoses, which were not usually confirmed until weeks after the
initial clinical testing.
The scientists found that patients in the early stages of
Alzheimer’s disease had a dramatic difference in detecting odor
between the left and right nostril — the left nostril was impaired
and did not detect the smell until it was an average of 10
centimeters closer to the nose than the right nostril had made the
detection in patients with Alzheimer’s disease.
This was not the case in patients with other kinds of dementia; instead, these patients had either no differences in odor detection between nostrils or the right nostril was worse at detecting odor than the left one.
Of the 24 patients tested who had mild cognitive impairment, which
sometimes signals Alzheimer’s disease and sometimes turns out to be
something else, about 10 patients showed a left nostril impairment
and 14 patients did not. The researchers said more studies must be
conducted to fully understand the implications.
“At the moment, we can use this test to confirm diagnosis,” Stamps
said. “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.”
Stamps and Heilman point out that this test could be used by clinics
that don’t have access to the personnel or equipment to run other,
more elaborate tests required for a specific diagnosis, which can
lead to targeted treatment. At UF Health, the peanut butter test
will be one more tool to add to a full suite of clinical tests for
neurological function in patients with memory disorders.
ALERT: 5 Signs You’ll Get Alzheimer’s Disease
One of the first places in the brain to degenerate in people with
Alzheimer’s disease is the front part of the temporal lobe that
evolved from the smell system, and this portion of the brain is
involved in forming new memories.
“We see people with all kinds of memory disorders,” Heilman said.
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.”
The study was published in the Journal of the Neurological
Sciences.
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