SEATTLE, August 8, 2018—Alzheimer’s disease is difficult to diagnose as well as treat, but researchers now have a promising new screening tool using a window to the brain: the eye.
A study of nearly 4,000 randomly selected patients at Kaiser Permanente in Washington found a significant link between Alzheimer’s disease and three degenerative eye diseases: age-related macular degeneration, diabetic retinopathy, and glaucoma.
The results offer health care providers a new way to detect people at higher risk of this disorder, which causes memory loss and other symptoms of cognitive decline.
The researchers, from the University of Washington (UW) School of Medicine, Kaiser Permanente Washington Health Research Institute, and the UW School of Nursing, reported their findings today in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association: “Associations between recent and established ophthalmic conditions and risk of Alzheimer’s disease.”
“We don’t mean people with these eye conditions will get Alzheimer’s disease,” said lead researcher Cecilia Lee, MD, MS, assistant professor of ophthalmology at the UW School of Medicine. “The main message from this study is that ophthalmologists should be more aware of the risks of developing dementia for people with these eye conditions and primary care doctors seeing patients with these eye conditions might be more careful on checking on possible dementia or memory loss.”
The participants in the study were age 65 and older and did not have Alzheimer’s disease at the time of enrollment. They were part of the Adult Changes in Thought (ACT) study started in 1994 by Eric B. Larson, MD, MPH, the executive director of Kaiser Permanente Washington Health Research Institute and a senior investigator there. Dr. Larson co-leads ACT, which is a longtime collaboration between Kaiser Permanente Washington Health Research Institute and the UW, with funding from the National Institute on Aging.
Over the current five-year study, a committee of dementia experts diagnosed 792 cases of Alzheimer’s disease. Patients with age-related macular degeneration, diabetic retinopathy, or glaucoma were at 40 percent to 50 percent greater risk of developing Alzheimer’s disease compared to similar people without these eye conditions. Cataract diagnosis was not an Alzheimer’s disease risk factor.
“What we found was not subtle,” said Paul Crane, MD, MPH, a professor of medicine at the UW School of Medicine’s Division of General Internal Medicine. “This study solidifies that there are mechanistic things we can learn from the brain by looking at the eye.” Dr. Crane is also an affiliate investigator at Kaiser Permanente Washington Health Research Institute and co-leads the ACT study.
More than 46 million older adults are affected by dementia worldwide and 131.5 million cases are expected by 2050, the researchers said. Alzheimer’ disease is the most common dementia, and discovering risk factors may lead to early detection and preventive measures, they said.
Dr. Lee said anything happening in the eye may relate to what’s happening in the brain, an extension of the central nervous system. The possible connections need more study. She said a better understanding of neurodegeneration in the eye and the brain could bring more success in diagnosing Alzheimer’s early and developing better treatments.
The researchers said several factors suggest the effects they uncovered were specific to ophthalmic conditions and not merely age-related phenomenon.
Dr. Larson said for years Alzheimer’s researchers were focused on amyloid buildup in brain tissue, but that hasn’t brought much benefit to patients.
“This paper is pointing to a new area of opportunity,” he said.
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