Cataract Surgery Seen Protective Against Dementia
Older patients who undergo cataract surgery may reduce their risk of developing dementia by roughly 30%, new research shows.
Although previous studies have linked sensory impairment to dementia, whether correcting vision problems in particular can prevent cognitive decline has been unclear, according to Cecilia S. Lee, MD, the Klorfine Family Associate Professor in the Department of Ophthalmology at the University of Washington, in Seattle, who led the study.
“Despite controlling for an extensive number of health-related factors and potential sources of bias that might have affected the relationship between cataract surgery and dementia, we still found strong associations between cataract surgery and reduced risk of dementia,” said Lee, whose group published their findings in JAMA Internal Medicine. “Cataract surgery was associated with an approximately 30 percent lower risk of developing dementia and we found similar associations with Alzheimer disease as well,”
For the analysis, Lee and her colleagues used data from the ongoing Adult Changes in Thought (ACT) study, a longitudinal analysis of more than 5000 people aged 65 years and older in the Seattle area who did not have dementia on enrollment. They included 3038 participants in ACT who had been diagnosed with cataracts or glaucoma before the onset of dementia. Of those, 1800 (59%) were women, 1238 (41%) were men, and nearly all (91%) were White. The mean age at cataract diagnosis was 74.4 years.
Among the study participants, 853 were diagnosed with dementia, and 709 with Alzheimer’s dementia. Roughly half the group (1382) underwent cataract extraction.
After controlling for factors linked to the risk of developing dementia, including smoking history, years of education, apolipoprotein E (APOE) genotype — which has been linked to dementia — and other factors, patients in the study who underwent cataract extraction were 29% less likely to develop dementia than those who did not undergo the procedure (hazard ratio [HR], 0.71; P < .001), Lee’s group found. They observed similar results for the development of dementia associated with Alzheimer’s dementia. However, glaucoma surgery did not appear to be linked to a reduction in the risk of dementia, they report (HR, 1.08; P = .68).
The reduction in risk was particularly strong in the first 5 years after surgery (HR, 0.68; P < .001). “When considering the relative associations of cataract extraction, additional education, White race, smoking history, sex, and APOE genotype with dementia risks, the only covariate that was more protective than cataract surgery was not having an APOE e4 allele,” the authors report.
A strength of the study, Lee said, was its dataset, which allowed the researchers to control for many confounding variables. “Healthier patients are usually more able to go through optional surgeries than people with many medical issues. So one could argue that the reduced dementia risk that we found was from people who had cataract surgery being healthier than people who did not have cataract surgery,” she said. “For this study, we had access to a unique dataset that allowed us to address many confounders, such as people’s health status and health behavior.”
Importance for Primary Care Providers
Lee said the study, which was not designed to look for potential mechanisms for the association, has important implications for primary care providers.
“To date, there are only a few known dementia risk factors that are modifiable, such as certain diets and increased activity level,” she said. “Our study results suggest that interventions to improve sensory impairment such as vision could play a role in preventing dementia or Alzheimer disease. Older adults who are experiencing symptoms of cataract, such as night driving difficulty or seeing halos around bright lights, should be evaluated by ophthalmologists.”
Her group has also found that several neurodegenerative eye diseases, such as age-related macular degeneration and diabetic retinopathy, are linked to an increased risk of dementia, as well as Alzheimer’s dementia. “Thus, primary care physicians who are taking care of older adults could play an important role in ensuring that older adults who are at risk of dementia are evaluated by ophthalmologists regularly,” she said.
Michael F. Chiang, MD, director of the National Eye Institute of the National Institutes of Health, in Bethesda, Maryland, which helped fund the research, said, “This study reinforces how closely the eye and the brain are linked, in this case through the association between cataract surgery and lower risk of dementia. I hope future studies will examine the underlying mechanistic relationships in more detail.”
The study was funded by the National Institutes of Health, the Alzheimer’s Drug Discovery Foundation, and Research to Prevent Blindness. Lee reported no relevant financial relationships. Several co-authors reported financial relationships with industry, a full listing of which is included in the original article.
JAMA Intern Med. Published online December 6, 2021. Full text
Adam Marcus is an editorial director at Medscape. He can be reached at [email protected]
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