Macular degeneration may be treatable with Parkinson's drug

Published: Tuesday 10 November 2015

The mountains of data collected on health, patients, treatments and disease create opportunities to mine them for new insights. Now, such an exercise has led to a potential breakthrough in the treatment of macular degeneration - the most common cause of blindness among older Americans.

The researchers found that taking L-DOPA, a medication often prescribed for the treatment of Parkinson's disease, also appears to protect against AMD.

Researchers have found it may be possible to delay or prevent macular degeneration using L-DOPA, a drug commonly used to treat Parkinson's disease. 

As many as 1.8 million Americans are affected by macular degeneration - often referred to as age-related macular degeneration (AMD) - an eye disorder associated with aging that impairs sharp and central vision.

AMD affects the macula - the middle part of the retina that allows the eye to see fine detail. As it progresses, the center of the field of vision becomes increasingly blurred, making it difficult to recognize faces, read and drive.

Part-funded by the BrightFocus Foundation - a non-profit research organization based in Clarkson, MD - the new study is the work of investigators from several research centers around the US, and is published in The American Journal of Medicine.

The study takes a novel approach to finding a new treatment for AMD, as senior author Brian McKay, a research associate professor in ophthalmology and vision science at the University of Arizona, explains:

"Rather than looking at what might cause AMD, we instead wondered why certain people are protected from AMD. This approach had never been done before."

The team started with the discovery that more highly pigmented or darker-colored eyes - which are known to be less prone to AMD - are more likely to have higher levels of a chemical called L-DOPA.

L-DOPA is often prescribed as a treatment for Parkinson's disease because it is a precursor of dopamine - the brain chemical that depletes in the brains of people with the disease.

Patients receiving L-DOPA less likely to develop AMD

The researchers wanted to find out if people who are prescribed L-DOPA for the treatment of Parkinson's or other diseases may also be protected from AMD. One way to do this is to look through data that has already been collected - a retrospective analysis.

The team first compared the incidence of AMD between patients taking L-DOPA and patients not taking the drug. They analyzed medical records from 37,000 patients from the Marshfield Clinic - a health care system in Wisconsin, with two hospitals and over 50 clinic locations.

This analysis revealed that patients receiving L-DOPA were significantly less likely to develop AMD, and when they did, it began much later.

The researchers then confirmed these first findings by analyzing a much bigger set of medical records from a Truven MarketScan database covering around 87 million patients worldwide.

In the second, larger analysis, the team found that taking L-DOPA also delayed or prevented AMD progressing from the "dry" to the "wet" form, where abnormal blood vessels leak fluid or blood into the macula region, resulting in rapid central vision loss.

The researchers conclude that taking L-DOPA medication appears to protect against AMD. They now plan to start a clinical trial to test how well it performs as such a treatment.

The study follows a report that  Medical News Today made earlier this year about a promising stem cell trial that brings closer a cure for wet AMD. The report is of a patient with wet AMD who had eye cells derived from stem cells transplanted behind the retina.

Written by Catharine Paddock PhD

Copyright: Medical News Today  

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