Sight, Smell Could Offer Early Warning of Alzheimer's

Researchers are exploring whether early detection of Alzheimer's can be made by a simple inexpensive eye exam. Other scientists are studying whether losing the ability to differentiate odors can be used to predict the disease, The Wall Street Journal reported.

Such tests could help provide timely warning of the incurable disease that robs people of their memory, the 2014 Alzheimer's Association International Conference now taking place in Copenhagen, Denmark, was told.

"In the face of the growing worldwide Alzheimer's disease epidemic, there is a pressing need for simple, less invasive diagnostic tests that will identify the risk of Alzheimer's much earlier in the disease process," Heather Snyder, the association's director of medical and scientific operations, said in a statement. "This is especially true as Alzheimer's researchers move treatment and prevention trials earlier in the course of the disease."

For now, there are no biological markers that can confirm the disease. The main way to diagnose Alzheimer's is through a clinical exam. Another approach used mostly in research is expensive brain imaging to identify clumped deposits of amyloid plaque.
Given that there is no cure, some people will not want to know if they are likely to be stricken.

The amyloid plaques associated with the diseased brain are also thought to be deposited in the eye lens and retina. Two companies, Cognoptix and CSIRO Australia, are working on early noninvasive eye-imaging technology that could detect the disease in patients who have few, if any, symptoms. Shaun Frost, a researcher at CSIRO described the retina as like a "piece of brain outside the brain," according to the Journal.

More work needs to be done to determine whether eye imaging will turn out to be a reliable way to identify Alzheimer's.

Another avenue being explored in smell impairment. The part of the brain that discerns odors is believed to be especially vulnerable to Alzheimer's. So far scratch-and-sniff smell tests have shown a correlation between odor impairment and onset of the disease.

Matthew Growdon at the Harvard Medical School has been studying the connection between smell as memory.

"Our research suggests that there may be a role for smell identification testing in clinically normal, older individuals who are at risk for Alzheimer's disease," Growdon said in the association's statement. "For example, it may prove useful to identify proper candidates for more expensive or invasive tests. Our findings are promising but must be interpreted with caution. These results reflect a snapshot in time; research conducted over time will give us a better idea of the utility of olfactory testing for early detection of Alzheimer's."

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