Home > Neurology > Cataract extraction linked to lower dementia risk

Cataract extraction linked to lower dementia risk

Journal
JAMA Internal Medicine
Reuters Health - 15/12/2021 -Cataract surgery was associated with a lower risk of developing dementia in a longitudinal cohort study.

"We have previously shown that several eye diseases, such as age-related macular degeneration and diabetic retinopathy, are associated with a 50%-60% increased risk of Alzheimer disease and dementia development," Dr. Cecilia Lee of the University of Washington in Seattle told Reuters Health by email.

"Sensory loss, including vision and hearing, is of interest...as a modifiable risk factor for dementia, and also as a potential point of intervention," she said.

Among hearing-impaired adults, hearing aid use has been independently associated with reduced dementia risk in cohort studies.

"Because cataract surgery improves visual function, we hypothesized that older people who undergo cataract surgery may have a decreased risk of developing Alzheimer disease and dementia," Dr. Lee said

In fact, she noted, "The participants with cataracts who underwent cataract surgery had nearly 30% lower risk of developing dementia from any cause compared with those who did not."

"We were able to control for an extensive number of health-related confounders and potential sources of biases," she noted. "Despite these analyses, we still found strong associations after accounting for these factors."

"We do not yet understand the potential mechanisms that could explain this association," she added. "However, the results of this study add to the body of evidence supporting the idea that improving vision helps to prevent the development of dementia."

As reported in JAMA Internal Medicine, the authors analyzed data from the Adult Changes in Thought study, an ongoing cohort of randomly selected, cognitively normal members of Kaiser Permanente Washington with a diagnosis of cataract or glaucoma.

A total of 3,038 participants (59% women; 91% white; mean age, 74) were included in the analysis. Based on 23,554 person-years of follow-up, cataract extraction was associated with a significantly reduced risk (hazard ratio, 0.71) of dementia compared with those without surgery after controlling for years of education, race, and smoking history, and stratifying by apolipoprotein E genotype, sex, and age at cataract diagnosis.

Notably, the finding of lower risk was stronger during the first five years following cataract surgery.

Similar results were seen in marginal structural models after adjustment for multiple potential confounders.

By contrast, glaucoma surgery was not significantly associated with dementia risk (HR, 1.08).

Similar results were found for the development of Alzheimer disease dementia - i.e., reduced risk with surgery for cataracts but not for glaucoma.

Dr. Lee added, "For clinicians, these findings highlight the importance of eye health in older adults. To date, there are few known measures, other than certain lifestyle factors such as diet and exercise, that are thought to be preventative against dementia. Our study suggests that treating cataracts may have additional benefits beyond improving visual acuity and visual function."

Dr. Elana Clar, a neurologist at New Jersey Brain and Spine in Oradell, commented in an email to Reuters Health, "The study was robust, but did not represent a diverse group of ethnic backgrounds, some of which are known to carry a higher risk for the development of Alzheimer's and other forms of dementia."

"I would like to see studies comparing different ophthalmological problems - e.g., halting macular degeneration, reduction in glaucoma pressures - to see if the same association could be found," she said. "If so, perhaps it is simply the visual impairment, and not the pathology, that increases the risk for dementia, thereby encouraging us to change how we counsel patients with regard to risk factors for the development of dementia."

"If not, then it would be interesting to see more ophthalmologic clinical data, such as visual acuity or cataract severity to show us what, specifically, about untreated cataracts that increases the risk for dementia," she said. "Or, conversely, what, specifically, about treated cataracts is it that leads to a risk reduction for the development of dementia?"

SOURCE: https://bit.ly/3dUtewF JAMA Internal Medicine, online December 6, 2021.

By Marilynn Larkin



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