Alcohol increases the risk of GA development. Photo: Wendy Harrison, OD, PhD, and Joe Wheat, OD, PhD. Click image to enlarge.

Scientists continue to explore risk factors for a variety of health conditions, including how genetics may help predict the development of disease. A recent study that relied on genetic evidence suggests alcohol consumption may lead to geographic atrophy (GA), while smoking habits could be tied to a greater risk of advanced age-related macular degeneration (AMD).

The UK-based study used a mendelian randomized framework to assess 16,000 individuals with AMD and 18,000 controls and explore potential causal associations between the risk of advanced AMD and the following modifiable risk factors: smoking, alcohol consumption, BMI, blood pressure and glycemic traits.

“We found genetic evidence supporting a potential causal association between smoking initiation and advanced AMD risk consistent with previous observational studies,” the authors wrote in their paper.

This association was stronger for wet AMD than for GA, and similar results were found for lifetime smoking behavior, they added. Additionally, smoking cessation was associated with a decreased risk of advanced AMD, specifically wet AMD, compared with persistent smoking.

“We also found suggestive evidence for a possible causal association between increased alcohol consumption and risk of advanced AMD that was likely driven by a strong association with GA,” the authors wrote.

As there are currently no known treatments for GA, this finding has important public health implications, the investigators suggested. These results also support previous observational studies associating smoking behavior with risk of advanced AMD, reinforcing existing public health messages regarding the risk of blindness associated with smoking, they added.

The researchers found a one-SD increase in log odds of genetically predicted smoking initiation and a higher risk of advanced AMD. On the other hand, they observed a one-SD increase in log odds of genetically predicted smoking cessation (former vs. current smoking) and a lower risk of advanced AMD.

Considering other possible risk factors, the authors found insufficient evidence to suggest that genetically predicted blood pressure, BMI and glycemic traits were associated with advanced AMD.

Kuan V, Warwick A, Hingorani A, et al. Association of smoking, alcohol consumption, blood pressure, body mass index, and glycemic risk factors with age-related macular degeneration a mendelian randomization study. JAMA Ophthalmol. November 4, 2021. [Epub ahead of print].