Combination of lifestyle and genetic risk factors leads to 'AMD'

The combination of diet, exercise, smoking status and genes drive the inflammation associated with age-related macular degeneration (AMD), according to the findings of a large study in the US.

The study, funded by the National Institutes of Health, looked at data from 1,663 women aged 50–79, taken from the Carotenoids in Age-Related Eye Disease Study (CAREDS), assessing their diet and exercise patterns, as well as their smoking status. Genetic data was also used to identify if they carried a known risk factor for AMD, a version of the complement factor H (CFH) gene, which plays a role in inflammation.

The results showed that a confluence of risk factors contributed to AMD. Those women who had smoked, were classed as high risk for diet and exercise and who had two copies of the faulty CFH gene, were four times more likely to develop AMD compared to women without genetic risk factors and who ate a healthy diet and who had a more active lifestyle.

However, the authors add that “unhealthy lifestyles increased AMD risk regardless of AMD risk genotype.”

Professor Julie A Mares, from the University of Wisconsin-Madison and senior author of the study, said: “If you have a family history of AMD, the good news is that the study findings suggest that there are things you can do to potentially lower your risk of developing AMD yourself.”

The recent findings from a second study of women taken from the CAREDS cohort showed that vitamin D levels may play a significant role in AMD development in those with underlying genetic risk.

“The findings of both studies support the notion of biologic synergy. That is, that one's genes, lifestyle factors and nutrition all come together in a synergistic way to mediate inflammation, which is a key mechanism involved in AMD,” said Professor Mares.

She added: “There's a large body of evidence that unhealthy lifestyle habits are associated with inflammation and that CFH risk alleles augment inflammatory responses. Vitamin D is believed to suppress inflammation, which is thought to enhance the AMD disease processes both directly and indirectly.”

The findings are published in Ophthalmology.