The study, recently published in the Neurobiology of Aging, is a joint effort of neurologist Dr. Patrick McGeer of UBC and rheumatologist Dr. John Sibley of the U of S.
The scientists found that that rheumatoid arthritis patients being treated with anti-inflammatory drugs were 10 times less likely to develop (AMD) than unaffected individuals in the United States, Australia, the Netherlands and the United Kingdom.
"Age-related macular degeneration is like Alzheimer's disease of the eye, with retinal deposits called drusen acting like amyloid deposits in the brain found in Alzheimer's," says McGeer, a UBC professor emeritus in the Kinsmen Laboratory of Neurological Research and expert in the use of non-steroidal anti-inflammatory drugs (NSAIDS).
The scientists reviewed 993 rheumatoid arthritis patients in Saskatchewan aged 65 years or older who, on average, had been living with the condition since age 51. Only three had developed AMD, where about 30 cases could be expected in a similarly-aged group from the general populace.
"It was natural for us to look at the rheumatoid arthritis population," says Sibley, a U of S professor of medicine and head of the division of rheumatology. "They have been followed closely for more than 40 years with particular attention paid to retinal changes because medication widely used for rheumatoid arthritis can create visual problems."
It is already accepted that NSAIDS reduce the incidence of bowel cancer. Fifteen years ago, McGeer and Sibley found the first of a growing body of evidence that NSAIDS may also help reduce the incidence of Alzheimer's. However, Sibley says this is the first time a link has been identified between anti-inflammatories and macular degeneration.
The researchers emphasize that further study is required to confirm their findings, but if they are corroborated, anti-inflammatories would be the first approach for this intractable disease. Related questions such as optimum dosage and when to begin treatment need to be answered. Also, since NSAIDS can have side effects such as stomach upset, ulcers and stress on kidneys, they are not appropriate for everyone and criteria for high-risk patients that would benefit from their use will need to be defined.
Macular degeneration is the most common cause of severe vision loss in Canada, especially among the elderly, according to the Canadian National Institute for the Blind. It causes one in three cases of reported vision loss. The condition causes light-sensitive cells in the macula, or central portion of the retina, to degenerate. The macula is responsible for perceiving fine visual detail. Early signs of macular degeneration include blurring of vision when performing detailed tasks like reading or sewing.
AMD is the most common form of the disease and causes permanent loss of central vision. There are two forms of AMD – wet and dry – with more than 85 per cent of cases being the dry form, for which there is no effective treatment.
McGeer and Sibley's work was supported through the Arthritis, Rheumatism, and Aging Medical Information System (ARAMIS) consortium through grants from the United States National Institutes of Health. Additional funding was provided through the Jack Brown and Family Alzheimer's Disease Foundation and the estate of George Hodgson.
Note: To view the paper, visit http://www.sciencedirect.com/science/journals, click on Neurobiology of Aging, Articles in Press. A PDF of the study is available upon request.
Journal
Neurobiology of Aging