Patients who develop age-related macular degeneration, diabetic retinopathy, or glaucoma are up to 50% more at risk of also developing Alzheimer's disease, according to a study led by the University of Washington School of Medicine (UWSOM).

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. “We don’t mean people with these eye conditions will get Alzheimer’s disease,” said lead researcher and assistant professor of ophthalmology at UWSOM Cecilia Lee. She said anything happening in the eye may relate to what’s happening in the brain, an extension of the central nervous system, and that 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 nearly 4000 participants in the study were age 65 and older and did not have Alzheimer’s disease at the time of enrollment. Over the five-year term of the study, a committee of dementia experts diagnosed 792 cases of Alzheimer’s disease. Patients with one of the three degenerative eye conditions were found to be at 40% to 50% greater risk of developing Alzheimer’s disease compared to similar people without these eye diseases. Cataract diagnosis was not an Alzheimer’s disease risk factor, said the researchers.

The researchers also said several factors suggest the effects they uncovered were specific to ophthalmic conditions and not merely age-related phenomenon. Professor Paul Crane of UWSOM’s division of general internal medicine said, “This study solidifies that there are mechanistic things we can learn from the brain by looking at the eye.”  

Executive director of Kaiser Permanente Washington Health Research Institute, Dr Eric Larson, who founded the Adult Changes in Thought (ACT) study of which this research was a part, said for years Alzheimer’s researchers were focused on amyloid buildup in brain tissue, but that hadn’t brought much benefit to patients. “This paper is pointing to a new area of opportunity,” he said.