September 2010

 

OPHTHALMOLOGY NEWS

 

Poor vision potentially spurring Alzheimer's disease


by Maxine Lipner Senior EyeWorld Contributing Editor

   

Checking in with an ophthalmologist may stave off cognitive decline

The appearance of dementia seems to be linked to a patient's vision, with elderly individuals with poor acuity more likely to experience cognitive decline over time. On the upside, other results published in the February 11 issue of the American Journal of Epidemiology indicate that when elderly patients visited an ophthalmologist at least once, there was a 63% reduction in risk of dementia, according to Mary A. M. Rogers, Ph.D., research assistant professor, University of Michigan, Ann Arbor, Mich.

"We were originally looking at a number of different procedures that proceed dementia," Dr. Rogers said. "We had linked the information from the Health and Retirement Study with Medicare information and we noticed that there was a deficit of eye-related procedures in those people who were eventually diagnosed with cognitive impairment or dementia."

Examining visual history

After noticing this, investigators set out to determine whether vision loss, no matter the cause, can result in cognitive impairment. Included in the retrospective study were 625 elderly Medicare recipients whose cognition was normal at baseline. "In this particular study there was careful attention paid to people who had normal cognition, patients who were cognitively impaired but had no dementia, and patients who had dementia and what type of dementia they had," Dr. Rogers said. "We also had their medical records over many years, so it was like recreating history."

When investigators delved into the records they found that those who had better vision at baseline were less likely to develop dementia. Only 9.7% of those who started with excellent vision went on to develop dementia. "Individuals who did not visit an ophthalmologist fared the worst," Dr. Rogers said. "They had an increased risk of Alzheimer's disease." Such individuals with poorer vision who did not visit an ophthalmologist over the mean follow-up period of 8.5 years had a 9.5-fold increased risk of developing Alzheimer's disease and a five-fold increase of cognitive impairment without dementia.

Possible links

Dr. Rogers sees a number of possible explanations here. "Lack of visual input does cause changes in the structure of the brain according to a number of studies by basic scientists," Dr. Rogers said "Another hypothesis that may be somewhat related is that proper vision is a requirement for a lot of activities that have already been shown to be preventative of Alzheimer's disease." Physical activity and incorporating games and puzzles such as Sudoku and crosswords into a patient's lifestyle have been shown to help keep Alzheimer's disease at bay. "It's not exactly predictive, but to do many of those activities you need proper vision, so maybe that's the link," Dr. Rogers said.

Another hypothesis is that those with vision problems such as cataracts or retinopathy who don't receive treatment for them become functionally incapacitated sooner. As a result, Dr. Rogers thinks that such patients will be diagnosed a bit earlier with dementia or cognitive impairment.

Yet another possibility is that poor vision is somehow a co-pathology here. "There are a number of different brain pathophysiologies running in concert," Dr. Rogers said. "In this case, beta amyloid plaques, which are the hallmarks of Alzheimer's disease, have been shown in basic science studies to be related to the etiology of glaucoma, for example." She points out that a study published in 2007 in the Proceedings of the National Academy of Sciences considered what happened when researchers stopped the beta amyloid pathway. "They prevented glaucoma and they noted that this is the same pathway that has been hypothesized for Alzheimer's disease," Dr. Rogers said. This leads some to think that intervening in that pathway with new drugs might remedy both diseases.

Regardless of the specific link, Dr. Rogers thinks that it's important to delve further. "A lot of earlier studies only discussed vision problems after a person was diagnosed with dementiavision problems were usually one of the first signs that a person had Alzheimer's," she said. "But people haven't looked at what comes first and I think that we have to sort it out." Overall, Dr. Rogers is gratified that study results here did show an improvement in cognitive outcomes for those who visited their ophthalmologist. "In a way it's hopeful because for people who have poor vision, it looks as if the treatment did help," she said. "For an elderly individual who has vision problems I would recommend going to see an eye doctor and getting treated."

Editors' note: Dr. Rogers has no financial interests related to her comments.

Contact information

Rogers
: 734-647-8851, maryroge@umich.edu

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