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February 17, 2013

Early detection of Alzheimer's disease

Scott Stockdale

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Dr. Melanie Campbell, a professor in the University of Waterloo's Department of Physics and Astronomy and the School of Optometry and Vision Science, and a team of researchers, are developing a tool that will allow for early detection of Alzheimer's disease.

Dr. Campbell said the new instrument will detect the presence of a protein called amyloid beta on the retina at the rear of the eye. Amyloid beta forms deposits in the brain in the early stages of Alzheimer’s disease. She said her team hopes to be able to image the living eye, and the amyloid beta deposits on the retina, which would indicate the presence of Alzheimer's disease and its progression.

Currently, Dr. Campbell's research team is testing retina from donors, looking for the protein in the neural layers of the retina. In general, they detect the amyloid beta in donors who had Alzheimer's disease and do not detect it in those who didn't. With the knowledge gained about the deposits, she and her collaborators are now perfecting a technique for imaging them in the living eye.  

“We are using the eye as a window to what is happening in the brain.”  

She said they hope to be able to use the tool to test and follow the progression of Alzheimer's disease on people within two to three years. With the technology now available, a definitive diagnosis of Alzheimer’s disease can only be given after death with an examination of the brain tissue of the deceased patient.  Early diagnosis is acknowledged to be important, as current treatments delay progression of the disease, resulting in better quality of life.

Doctors currently use MRI's and PET's (positron image tomography) to try and detect the presence of Alzheimer's disease in patients, but Dr. Campbell said the technique she's developing would not only be more accessible and less expensive than these brain imaging techniques, it would also be non-invasive.

  1. “We use two methods: the intraction method shines light on the deposits and the surrounding tissue and then examines the light that comes back. The second method is called spectroscopy. We shine light on different tissues and measure the different wavelengths (of light) they absorb. Each tissue has a particular signature the wavelengths it absorbs. Amyloid beta deposits are expected to have a different signature than surrounding tissue.

Dr. Campbell and her team includes researchers from physics, as well as biophysicists and neurologists. She said people don't think of physicists working with experts in the medical and health disciplines, but a multi-disciplined effort is essential in order to solve current medical problems.

“My expertise is in imaging. We need others with expertise in disease and protein analysis. Physics is important to medical research. We use physics techniques and understanding to solve medical and biological problems.”

She added that the University of Waterloo's life physics undergraduate program is a new program of study which incorporates these different interrelated disciplines.

Last fall, the Canadian Institute of Health Research (CIHR) and the Natural Sciences and Engineering Research Council of Canada (NSERC) gave Dr. Campbell and her team of researchers a $490,000 grant, which Dr. Campbell said is aimed to encourage experts in the physical sciences and engineering to work with experts the health sciences.

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