A team of researchers in the U.S. believe that a simple eye exam may be able to screen patients for Alzheimer鈥檚 disease long before they exhibit symptoms or signs of dementia.
鈥淭he eye can really serve as a model for studying neurodegenerative diseases,鈥� Dr. Gregory Van Stavern, professor of ophthalmology and visual sciences at Washington University in St. Louis, told 麻豆影视. 鈥淎nd we can access the eye a lot easier than we can access the brain.鈥�
Scientists know that Alzheimer鈥檚 and dementia can begin to take root in the brain up to two decades before symptoms such as memory loss or mood changes become obvious. And while simple tests currently exist for the early discovery of diseases such as colon cancer and diabetes, there is nothing comparable when it comes to Alzheimer鈥檚. Today, only tests such as spinal taps or PET scans can detect Alzheimer鈥檚 in its earliest stages.
鈥淵ou can imagine those are invasive tests,鈥� Van Stavern said. 鈥淭hey鈥檙e expensive and very difficult to apply to the general population.鈥�
In , Van Stavern and a team of researchers used a relatively simple exam to study the eyes of 30 seniors. Although none of their subjects exhibited symptoms of Alzheimer鈥檚, PET scans and/or spinal taps had previously revealed that 17 of them were at risk of developing the disease in the future due to elevated levels of brain plaque.
Through the eye exams, which use a technology similar to what is already found in many eye doctors鈥� offices, the researchers discovered that those 17 had thinner retinas -- the part of the eye that converts images into signals for the brain -- as well as fewer blood vessels in their retinas than the other research subjects, signalling less blood flow in the eyes and brain.
Dr. Rajendra S. Apte, who also teaches ophthalmology and visual sciences at Washington University, co-authored the study.
鈥淲hat we wanted to examine was whether we could use the eye as a window to the brain,鈥� he told 麻豆影视.
鈥淭he finding that there were abnormalities in the blood vessels in the eye so early in disease was very surprising,鈥� he added. 鈥淪o this tells us that there are things going on very early in disease that we should be looking for even in the brain.鈥�
Although more research needs to be done to definitively prove a link between the state of one鈥檚 retinas and Alzheimer鈥檚, if verified it could mean that the disease can be detected earlier and easier, thus improving treatment and patient outcomes.
鈥淪ince these pathologic changes in Alzheimer鈥檚 disease begin about 20 years before dementia develops, it means practically by the time someone develops dementia there is so much loss of neural tissue that the medications, the treatments are not very effective,鈥� Van Stavern explained. 鈥淭here鈥檚 a push now to start intervening early in the preclinical stage with medications鈥� So the idea would be using a test like this, which is non-invasive, as a way of screening people who might be at risk for Alzheimer鈥檚 disease.鈥�
Meanwhile in Canada, a Montreal-based company called believes they have developed another test for detecting Alzheimer鈥檚 via a relatively simple, but somewhat different, type of retinal examination. The company, which is currently conducting clinical trials in collaboration with McGill University in Montreal and Sunnybrook Hospital in Toronto, is hoping to receive regulatory approval for its test in 2019.
The development of such quick, inexpensive and non-invasive eye tests are welcome news to Alzheimer Society of Canada CEO Pauline Tardif.
鈥淎ny disease modifying therapies that might be developed in the future will be most effective at the very, very early stages of the disease,鈥� she told 麻豆影视. 鈥淎nd if we can have鈥� diagnostic tools such as this through the retina, that鈥檚 really exciting.鈥�
With a report from CTV Medical Correspondent Avis Favaro and senior producer Elizabeth St. Philip
