ANN ARBOR, Mich. -- Elderly people with visual disorders that are left untreated are significantly more likely to develop Alzheimer's disease -- the most common form of dementia, according to a University of Michigan Health System study.
The study used Medicare data and shows that those with poor vision who visited an ophthalmologist at least once for an examination were 64 percent less likely to develop dementia.
The study appears online ahead of print in the American Journal of Epidemiology and may draw a new picture of poor vision as predictor of dementia rather than as a symptom after the diagnosis.
"Visual problems can have serious consequences and are very common among the elderly, but many of them are not seeking treatment," says lead author Mary A.M. Rogers, Ph.D, research assistant professor of internal medicine at the U-M Medical School and research director of the Patient Safety Enhancement Program at the U-M Health System and the Ann Arbor VA Medical Center.
For the study, Rogers and her colleague Kenneth M. Langa, M.D., Ph.D., professor of internal medicine at U-M Medical School, analyzed data from the nationally representative Health and Retirement Study and records from Centers for Medicare and Medicaid Services.
"Our results indicate that it is important for elderly individuals with visual problems to seek medical attention so that the causes of the problems can be identified and treated," Rogers says.
The types of vision treatment that were helpful in lowering the risk of dementia were surgery to correct cataracts and treatments for glaucoma, retinal disorders and other eye-related problems.
Proper vision is a requirement for many of the activities that previously have been found to lower the risk of Alzheimer's disease. These include reading, playing board games, other mentally stimulating activities, social networking, as well as physical activity such as walking and routine exercising. A visual disorder may interfere with normal mobility and may also hinder a person's ability to participate in such activities.
"Many elderly Americans do not have adequate health coverage for vision, and Medicare does not cover preventative vision screenings for most beneficiaries," Rogers says. "So it's not unusual that the elderly receive vision treatment only after a problem is severe enough to warrant a visit to the doctor when the problem is more advanced."
According to a survey conducted by the National Eye Health Education Program, less than 11 percent of respondents understood that there are no early warning signs for eye problems such as glaucoma and diabetic retinopathy.
However, vision problems and blindness are among the top 10 disabilities among adults and can result in a greater tendency to experience other health conditions or even to die prematurely.
"While heart disease and cancer death rates are continuing to decline, mortality rates for Alzheimer's disease are on the rise," says Rogers. "So if we can delay the onset of dementia, we can save individuals and their families from the stress, cost and burden that are associated with Alzheimer's disease."
The study was based on the surveys and medical information from 625 people compiled from 1992-2005. Only 10 percent of Medicare beneficiaries who developed dementia had excellent vision at the beginning of the study, while 30 percent of those who maintained normal cognition had excellent vision at the onset of the study.
One in five Americans who are over age 50 report experiencing a visual impairment, according to the U.S. Centers for Disease Control and Prevention. Approximately 5 million Americans have Alzheimer's disease and the number has doubled since 1980. It is expected to be as high as 13 million by 2050.
Additional author: Kenneth M. Langa, M.D., Ph.D., is also a researcher at the Veterans Affairs Center for Practice Management and Outcomes Research and Institute for Social Research
Reference: American Journal of Epidemiology, 2010 Feb. 11; doi:10.1093
Funding: National Institute on Aging
National Institute on Aging
American Journal of Epidemiology
U-M Medical School
Patient Safety Enhancement Program