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Cataracts affect most older adults at risk for dementia, and now researchers are finding strong evidence that cataract surgery is associated with a lower risk of developing dementia.
Based on the longitudinal data of over 3,000 Adult Changes in Thought (ACT) study participants, researchers have now found that subjects who underwent cataract surgery had nearly 30% lower risk of developing dementia from any cause compared with those who did not.
Study results were reported in JAMA Internal Medicine earlier this year.
The ACT study is a longstanding, Seattle-based observational study at Kaiser Permanente Washington of more than 5,000 participants older than 65.
Results showed this lowered dementia risk persisted for at least a decade after surgery. Cataract surgery was also associated with lower risk of Alzheimer’s disease dementia specifically.
Lead researcher Dr. Cecilia Lee, associate professor and Klorfine Family endowed chair in ophthalmology at the University of Washington School of Medicine, said the observational study adjusted for a number of potential confounders, yet still yielded a strong association.
“This kind of evidence is as good as it gets in epidemiology,” Lee said. “This is really exciting because no other medical intervention has shown such a strong association with lessening dementia risk in older individuals.”
Researchers hypothesize that people may be getting higher-quality sensory input after cataract surgery, which might 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 co-author Dr. Eric B. Larson, a principal investigator of the ACT study and senior investigator at Kaiser Permanente Washington Health Research Institute.
Lee said another hypothesis is that after cataract surgery, people are getting more blue light.
“Some special cells in the retina are associated with cognition and regulate sleep cycles, and these cells respond well to blue light,” she said. “Cataracts specifically block blue light, and cataract surgery could reactivate those cells.”
The study results highlight a strong case for further research on the eye-brain connection in dementia.
Previous studies by Lee’s group at the UW have shown a strong link between other retinal diseases, such as age-related macular degeneration, and the development of Alzheimer’s disease and dementia.
Subjects with macular degeneration or other retinal degenerative diseases are more likely to develop dementia.
Further understanding the connection between the aging eye and brain may offer insights and potential therapies to slow or prevent age-related dementia.