Eye tests may be able to detect Alzheimer's disease decades before onset, according to a recent study CBS News reported.

Researchers found that examinations of the eye could indicate the build-up of beta-amyloid, a protein associated with Alzheimer's, in the brain.

"What makes it unique is that the retina is actually an extension of the brain and so we think that a lot of the pathology that is occurring in the brain may also be occurring in the retina," Dr. James Galvin, neurologist at New York University Langone Medical Center, told CBS News.

For the study, Australian researcher Shaun Frost and colleagues tested 40 people using a liquid form of curcumin, the natural substance that makes curry yellow. The substance, which has fluorescent properties, binds to beta amyloids and allows doctors to spot the proteins with a simple eye test.

According to researchers, Preliminary results suggest that amyloid levels detected in the retina were significantly correlated with brain amyloid levels as shown by PET imaging. The retinal amyloid test also differentiated between Alzheimer's and non-Alzheimer's subjects with 100 percent sensitivity and 80.6 percent specificity.

"We envision this technology potentially as an initial screen that could complement what is currently used: brain PET imaging, MRI imaging, and clinical tests," researcher Shaun Frost said in a statement. "If further research shows that our initial findings are correct, it could potentially be delivered as part of an individual's regular eye check-up. The high resolution level of our images could also allow accurate monitoring of individual retinal plaques as a possible method to follow progression and response to therapy."

Currently, more than 5 million Americans have the degenerative brain disease, and that number is expected to increase dramatically in the decades ahead, according to CBS News.

"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, Alzheimer's Association 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."