The eye doctor’s office might be a place where Alzheimer’s disease is diagnosed in the future, if early research from Georgetown University Medical Center (GUMC) and the University of Hong Kong, which found a link between the disease and vision loss, holds up under further scrutiny. Other new research, however, finds that although Alzheimer’s and age-related macular degeneration (AMD) share risk factors, those with the eye disease are not at increased risk for developing Alzheimer’s or another form of dementia.
The GUMC/Hong Kong team reported Nov. 13 at the annual meeting of the Society for Neuroscience that the loss of a particular layer of previously uninvestigated cells in the retina—the tissue lining the inner surface of the eye—may reveal the disease's presence and provide a new way to track disease progression. "The retina is an extension of the brain, so it makes sense to see if the same pathologic processes found in an Alzheimer's brain are also found in the eye," says R. Scott Turner, MD, PhD, director of the memory disorders Program at GUMC and the only U.S. author of the study.
The researchers looked at the thickness of the retina in the eyes of mice genetically engineered to develop Alzheimer's disease. They found a significant loss of neurons compared with healthy, age-matched control mice.
"This study suggests another path forward in understanding the disease process and could lead to new ways to diagnose or predict Alzheimer's that could be as simple as looking into the eyes," Turner says.
The other research involved people in England who have AMD; findings were reported online by JAMA Ophthalmology. The investigators, from the University of Manchester and the University of Oxford, studied whether patients admitted to the hospital with AMD were more likely to develop Alzheimer’s or dementia subsequent years.
Using a group of 65,894 people with AMD from data in the English National Health Service, as well as a dementia group with 168,092 people and a reference group of more than 7.7 million people, researchers measured the risk of Alzheimer’s or dementia following AMD and the risk of AMD following Alzheimer’s or dementia. They found that although AMD and Alzheimer’s share environmental risk factors—cigarette smoking, hypertension and high cholesterol and other features such as the depositing of plaques in the brain—the genetic risk factors for AMD and Alzheimer’s appear to be different. The risk of developing Alzheimer’s or dementia after AMD was not elevated, although the investigators found that those with dementia—at least in England—are less likely to receive treatment for AMD than those without dementia.
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