A Canadian team has developed a new diagnostic tool that identifies features of the brain tied to Alzheimer’s disease that could allow doctors to detect a person’s likelihood of developing the debilitating condition years before such symptoms as memory loss appear.

The advance, unveiled at the world's largest Alzheimer's conference this week, was detailed in two new studies reported by University of Waterloo researchers.

Alzheimer's disease, which strikes about 5 million Americans, is difficult to diagnose and nearly impossible to catch early.

But the Waterloo researchers report that a new type of non-invasive eye scan — developed and patented by professor Melanie Campbell — uses polarized light to highlight deposits called amyloid proteins found at the back of patients' retinas decades before they experience cognitive decline.

Such proteins are common features in the brains of Alzheimer’s patients and block communication between brain cells, which leads to memory loss and other problems.

Campbell’s research, presented at the 2016 Alzheimer's Association International Conference in Toronto, could help speed therapeutic drugs and other approaches that might stave off dementia.

"Polarization imaging is promising for noninvasive imaging of retinal amyloid deposits as a biomarker of Alzheimer's," said Campbell.

"The ability to detect amyloid deposits in the retina prior to disease symptoms may be an essential tool for the development of preventative strategies for Alzheimer's and other dementias."