Loss of Smell May Predict Alzheimer's Disease

(Ivanhoe Newswire) -- Olfactory dysfunction, a common symptom of Alzheimer’s Disease (AD), may serve as an early diagnostic tool for the disease.

The formation of amyloid plaques and neurofibrillary tangles are believed to contribute to the degradation of neurons in the brain and subsequent symptoms of AD. Scientists at NYU Langone Medical Center used genetically engineered mice, which developed amyloids in their brains in a progressive Alzheimer's disease pathology similar to humans. The researchers found that AD amyloid pathology occurred first in a region of the mouse brain responsible for smelling, directly above their noses. The mice with a high of amyloid concentrations had to sniff odors longer to "learn" them. They also had problems differentiating between odors.

Since the behavioral symptoms of AD can often occur early in life, it is possible that looking at olfactory perception across multiple presentations of the same odor may be advantageous in early detection of Alzheimer's -- prior to substantial degeneration of the brain.

"What was striking in our study, was that performance of the mouse in the olfactory behavior test was sensitive to even the smallest amount of amyloid presence in the brain as early as three months of age (equivalent to a young adult). 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," co-author Daniel W. Wesson, PhD, of the NYU School of Medicine and the Nathan S. Kline Institute for Psychiatric Research in Orangeburg, NY, were quoted as saying.

Study co-author Ralph A. Nixon, MD, PhD, professor of Psychiatry and Cell Biology at NYU Langone Medical Center, was quoted as saying, "These novel results provide a two-fold benefit, not only in confirming that olfactory problems may serve as an early indicator of Alzheimer's, but that further validation in humans could facilitate testing of new therapies for the disease."

SOURCE: Journal of Neuroscience, January 13, 2010 

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