Loss of Smell Could Be Early Alzheimer's Indicator

A study conducted on unsuspecting lab mice demonstrated that the loss of smell might be a clear, early indicator of the onset of Alzheimer's Disease (AD), and also that healthcare experts could use this to their advantage. The sooner the condition is identified, the better for the patient. The advanced stages of the disease cannot be fought efficiently, doctors say, so prevention and early detection remain the only two methods of ensuring no one suffers the ill-effects of AD. Details of the new investigation appear in the January 13 issue of the Journal of Neuroscience, PhysOrg reports.

The work was conducted on animal models that had amyloid beta (protein) accumulations in their neural pathways. In humans, this is considered to be a clear indicator of AD, as all patients diagnosed with the condition have these structures clogging their nerve channels. These accumulations are also the main reason why cognitive capacity diminishes in people suffering from this terrible condition. Their brain's ability to send, receive, and interpret electrical impulses is severely affected, and a host of negative side-effects flow from this, doctors say.

Experts from the NYU Langone Medical Center, who conducted the new work, say that experiments focused on genetically engineered mice that were specifically bred to develop amyloid accumulations in their brains. The researchers then looked at very young mice, and determined that the first signs of AD appeared in the olfactory region of the brain, just above the nose. It was also determined that the mice engineered to exhibit large concentrations of the protein took longer to familiarize themselves with various smells, and that they had a lower sensitivity in differentiating between similar odors.

“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,” NYU School of Medicine expert Daniel W. Wesson, PhD, a coauthor of the new paper, says. He also holds an appointment in the Nathan S. Kline Institute for Psychiatric Research, in Orangeburg, New York.

“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,” the Director of the NYU LMC Center of Excellence on Brain Aging, Ralph A. Nixon, MD, PhD, adds. He is also an NYU professor in the Departments of Psychiatry and Cell Biology, and a coauthor of the journal entry.