Posted on 12/09/2021 10:29:48 AM PST by Red Badger
Cataract surgery was also associated with lower risk of Alzheimer’s disease dementia specifically.
Results reported in JAMA Internal Medicine associate cataract surgery with 30% lower risk of dementia in aging population.
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.
The Adult Changes in Thought (ACT) study is a long-standing, Seattle-based observational study at Kaiser Permanente Washington of more than 5,000 participants older than 65. Based on the longitudinal data of over 3,000 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. This lowered risk persisted for at least a decade after surgery. Cataract surgery was also associated with lower risk of Alzheimer’s disease dementia specifically. The results were reported on December 6, 2021, in JAMA Internal Medicine.
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.”
The mechanisms by which cataract surgery and lessened dementia risk are associated was not determined in this study. 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, In the current study, subjects undergoing vision-improving cataract surgery had lower risk of developing dementia. Further understanding the connection between the aging eye and brain may offer insights and potential therapies to slow or prevent age-related dementia.
The study: Researchers tracked participants diagnosed with a cataract or glaucoma but who did not have dementia at the time they volunteered for the study. Participants also did not have cataract surgery at the time of enrollment. Participants are evaluated every two years for cognitive abilities based on the Cognitive Abilities Screening Instrument, which scores in a range from 0-100. Participants with scores less than 85 undergo further neurological tests.
During follow-up of 3,038 participants (an average of 7.8 years per person), 853 subjects developed dementia, with 709 cases of Alzheimer’s disease. Approximately half of the participants (1,382 individuals, or 45%) had cataract surgery. Analysis for risk of developing dementia showed that subjects who had undergone cataract surgery in either eye were about 30% less likely to develop any form of dementia for at least 10 years after their surgery.
Analysis was adjusted for an extensive list of factors including health-related confounders. Cataract surgery could appear to have a protective effect due to a healthy patient bias, where participants who underwent cataract surgery might have been healthier and at lower dementia risk. Researchers performed analyses to account for several types of potential bias, but still found strong associations when these factors were accounted for.
Researchers excluded eye surgeries in the two years prior to dementia diagnosis to rule out the possibility that people with cognitive decline prior to dementia diagnosis may have been less conscious of vision issues, and thus less likely to have undergone cataract surgery. Even with this group excluded, the researchers found lower risks of dementia associated with cataract surgery.
As another control, participants were also evaluated for a possible link between eye surgery for glaucoma and dementia. No association was found.
Strengths of study: This was a community-based, prospective cohort study with more than 23,000 person-years of follow up. More than 98% of the ACT cohort were seen at least once by eye care clinicians, with an average of 27 encounters. Dementia diagnoses were made by a panel of experts using research criteria. The possibility of healthy patient bias and potential confounders were thoroughly investigated.
Limitations of study: Results could be explained by unmeasured or residual confounding factors, like any observational study. There could be coding errors for cataract diagnosis. Only the participant’s first cataract surgery was evaluated so researchers don’t know whether subsequent surgeries impacted dementia risk. The majority of the study population was White, and it is unclear if the effect would be observed in all populations.
“Innovative research like Dr. Lee’s is helping to uncover how age-related changes in our senses contribute to dementia,” said Dr. Howard Fillit, founding executive director and chief science officer of the Alzheimer’s Drug Discovery Foundation (ADDF), a nonprofit dedicated solely to accelerate the discovery and development of drugs to treat and prevent Alzheimer’s disease and related dementias.
Reference: “Association Between Cataract Extraction and Development of Dementia” by Cecilia S. Lee, MD, MS; Laura E. Gibbons, PhD; Aaron Y. Lee, MD, MSCI; Ryan T. Yanagihara, MD; Marian S. Blazes, MD; Michael L. Lee, PhD, MPH; Susan M. McCurry, PhD; James D. Bowen, MD; Wayne C. McCormick, MD, MPH; Paul K. Crane, MD, MPH and Eric B. Larson, MD, MPH, 6 December 2021, JAMA Internal Medicine. DOI: 10.1001/jamainternmed.2021.6990
As part of its Diagnostics Accelerator research initiative, the ADDF is also supporting Lee’s work to develop new diagnostic tools for Alzheimer’s that use non-invasive imaging of the retina and artificial intelligence.
The study was funded by National Institutes of Health (K23EY029246, R01 AG060942, P50 AG05136, U01AG006781, U19 AG066567), an Alzheimer’s Drug Discovery Foundation Diagnostics Accelerator Award, a Latham Vision tion Award, and an unrestricted grant from Research to Prevent Blindness.
In my dad’s later stages he couldn’t read his name.
I am still two hours from procedure to eye patch.
Do I feel 15% less demented yet per single eye effect?
Maybe. The yellow content has dropped substantially.
Maybe the straining gets blood flow to the brain?...................
No! Two eyes equal 60% less chance. ;-)
Correlation is not causation.
This is a nice factoid, but it is essentially meaningless until some causative link between getting cataract surgery and a lower risk of Alzheimer’s is proven. What mechanism is involved? - answering that question is the key here.
I had cataract surgery last year but now I’m suffering with rather large floaters which sometimes seem worse than the cataracts were. I might need surgery for the floaters. If anyone has experience in this I’d appreciate some input.
I have read separately that some post cataract surgery patients remark on everything looking blueish for a week or two.
....without even an attempt to isolate cause and effect. How many dementia patients are going to go in for cataract surgery? Duh.
I’ll bet the incidence of cataracts, as opposed to cataract surgery, is WAY higher among dementia patients.
Just make sure you find a surgeon with an impeccable, lengthy record and no corneas damaged. It happened early on, not sure about now.
I think that what may be at work is not the cataract surgey, but the fact that people who develop cataracts are more active outdoors. So it is the activities leading to the development of the cataract that needs surgery that is the main factor.
” How many dementia patients are going to go in for cataract surgery? “
Lots of mild dementia patients do.
Sunlight exposure can cause cataracts so they would also have a buildup of Vitamin D....................
Maybe cataract surgery stimulates the use of more Viagara.
Apparently, before my Dad turned 76, his cataracts basically blinded him. At that time mid 1970’ cataracts were a heavy duty surgery and patients had to be immobile for days post surgery. He was a regular patient at his local VA hospital, and he said no way.
He and my Mother did’t tell us about this. They bought a big screen tv and put his Lazy Boy close to the set. He rediscovered the radio. My Mother was a retired reading teacher and read to him. He love westerns and the Old Man and the Sea. She read the local paper’s comics and shared the crossword puzzle with. I lived 1800 miles away and didn’t know what was happening as no one told me. Later our mother said that sometimes she read the same chapter or whatever several times. She didn’t realize what was happening to him mentally. He died in that chair listening to my Mother read to him.
Later a decade plus, my mother decided to go into a senior citizen’s home. I went back and spent a week with her sorting out what to give away, what to throw away and what to keep. I noticed that she didn’t want to drive. She had a new little Olds that she loved and she had me drive.
When, she sat in front of the big TV and in Dad’s chair, it dawned on me that she probably had cataracts. At first she denied it and then admitted it. She didn’t want a long postop, and I told her that the new procedures didn’t require that.
Shortly after we got her moved into supposedly and temporarily a nice condo. She consented to surgery for one eye. It was successful, and she drove afterwards. Then, she had the second surgery and was basically 20/20 for the rest of her life.
She did move into that retirement home after a few years and drove her little car safely for about a decade. About once every two weeks, she and a car load of friends drove/rode to a great cafeteria. They bought home enough left overs to have shared lunches/brunches for a few days.
I turned 58 and developed cataracts quickly, I thought. I had the adapting lens inserted into my dominant eye and my wife drove me home. Later I was out in our front yard and noticed that the neighbor across the street had what looked like new street number on a new mail box.
My wife informed me that the box and number were over 6 months old. My vision had really deteriorated. The next day I drove to the Ophthalmologist’s office for the followup care. I couldn’t believe how clear everything was. A few weeks later, I had the second operation. My vision was the best I ever had and was 20/10.
I would have been depressed or worse, if I hadn’t had my cataracts removed and replaced with the adaptable ones.
nagant: How many dementia patients are going to go in for cataract surgery?
steve86: Lots of mild dementia patients do.
Sure they would. But a large portion of more severe dementia patients, the ones requiring help, would by no means seek surgery for their cataracts. And that would explain the link which this study draws between cataract surgery and dementia. The people showing up for cataract surgery are not people who couldn’t recognize their cataracts, much less seek treatment for them.
Cataract surgery is NOT a marker of cataracts among cognitively impaired people.
Apples keep elephants out of trees. Have you seen any elephants in apple trees?
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