Cataracts – cloudy areas in the lens of the eye leading to decrease in vision – affects a large number of older adults. A new study published in the journal JAMA Internal Medicine has found that cataract surgery is associated with a lower risk of developing dementia.
Based on longitudinal data of over 3,000 participants in the Adult Changes in Thought (ACT) observational study at Kaiser Permanente Washington, a research team led by the University of Washington School of Medicine discovered that subject who underwent cataract surgery had almost 30 percent lower risk of developing dementia from any cause. This lowered risk persisted for at least ten years after the surgery.
“This kind of evidence is as good as it gets in epidemiology,” said study lead author Cecilia S. Lee, an associate professor of Ophthalmology at UW School of Medicine. “This is really exciting because no other medical intervention has shown such a strong association with lessening dementia risk in older individuals.”
Although the precise mechanisms by which cataract surgery and lowered risks of dementia were associated have not been determined in this study, scientists hypothesize that the fact that people are getting higher quality sensory input after cataract surgery may have a beneficial effect in reducing the risk of dementia.
“These results are consistent with the notion that sensory input to the brain is important to brain health,” said study co-author Dr. Eric B. Larson, a principal investigator in the ACT study and senior researcher at Kaiser Permanente.
Another hypothesis could be that, after cataract surgery, people are getting more blue light, which improve sleeping patterns and thus increase cognitive functioning. “Some special cells in the retina are associated with cognition and regulate sleep cycles, and these cells respond well to blue light. Cataracts specifically block blue light, and cataract surgery could reactivate those cells,” Professor Lee explained.
Further research on the eye-brain connection in aging is needed in order to better understand how age-related vision problems could affect cognitive functioning. Clarifying these issues may offer new insights and potential therapies to slow or even prevent the development of age-related dementia.