Mice with Alzheimer's disease have a reduced sense of smell, according to a new study. The study adds weight to observations that people with the disease often have difficult detecting odors. But researchers have struggled to understand what the olfactory system losses have to do with the disease.
Alzheimer's disease results in accumulations of amyloid protein in the brain -- sometimes called plaques -- which impairs brain function and causes the symptoms of the disease. Researchers from New York University Langone Medical Center studied genetically engineered mice that were predisposed to develop amyloid proteins in the brains. They found that the buildup of amyloid protein occurred first in a region of the mouse brain responsible for smelling. These mice also showed an inability to smell. Those with more amyloid plaque in their brains had to sniff odors longer to learn them than mice with less amyloid.
The study provides evidence that declines in the sense of smell found in Alzheimer's patients may stem from the amyloid beta deposits in specific regions of the olfactory system and that this is among the first evidence of disease. The knowledge could lead to some kind of early-detection diagnostic test for the disease.
"This is a revealing finding because unlike a brain scan, a laboratory-designed olfactory test may be an inexpensive alternative to early diagnosis of Alzheimer's," said a co-author of the study, Daniel W. Wesson, in a news release.
The study is published this week in the Journal of Neuroscience.
-- Shari Roan
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