Eye Exam May Predict Alzheimer’s Disease

Washington University School of Medicine researchers have detected evidence suggesting Alzheimer’s in older patients without symptoms of the disease using technology similar to what would be found at many eye doctor’s offices. There is potential to use this technique as a screening tool to help determine who needs to undergo more testing for the disease prior to appearance of clinical symptoms. Goal is to use the technique to gain better understandings of why and who is accumulating abnormal proteins within the brain that may lead to the development of the disease.

Disease related damage can actually occur years before any symptoms appear. Alzheimer’s related plaques are estimated to build up in the brain 2 decades before onset of symptoms, researchers have been working on methods to detect the disease sooner; currently invasive and costly PET scans and lumbar punctures are used to help diagnose the disease.

Previous studies examining eyes of people with the disease who had died from Alzheimer’s reported their eyes had showed signs of thinning in the center of the retina and degrading of the optic nerve. This study used noninvasive optical coherence tomography angiography techniques to examine retinas in eyes of 30 subjects with an average age in the mid 70s of which none exhibited any clinical symptoms of Alzheimer’s disease enrolled from The Memory and Aging Project. PET scans or cerebrospinal fluids testing revealed that 17 of the subjects had elevated levels of Alzheimer’s proteins amyloid or tau, suggesting they likely would develop the disease even though they did not display symptoms; the other 13 subject’s test analyses were normal.

The technique uses a light shined into the eye allowing for measurements to be taken of retinal thickness and thickness of fibers in optic nerves, and angiography allowing red blood cells and blood flow patterns to be distinguished from other retina tissue. 17 subjects with elevated tau or amyloid levels had significant thinning in the center of the retina, showing preclinical Alzheimer’s the area at the center of the retina without blood vessels was significantly larger suggesting less blood flow.

Additional studies are required in patients to replicate findings, if changes detected with the technique can be used for markers of the disease it may be possible to screen patients for risk in their 40s-50s to determine if they are at risk for the development of Alzheimer’s disease.