Improved vision may help improve or maintain cognitive ability, research suggests.
Visual impairment in older adults may be harmful to cognitive function. A U.S. study published in JAMA Ophthalmology in September 2017 found that the rate of dementia and cognitive impairment was up to 2.8 times higher for participants with vision loss. A study of 2,520 older adults in the September 2018 JAMA Ophthalmology similarly found that worsening vision was associated with worsening cognition. A new investigation assessing more than 3,000 adults older than 64 with cataracts contributes to this body of research.
Cataracts cause the lens of the eye to become opaque. Research published December 6 in JAMA Internal Medicine found that for individuals who had their cataracts removed, the risk of developing dementia decreased by about 30 percent.
Study authors noted that lower risk was stronger during the first five years after cataract surgery than in later years.
“Cataracts may decrease neuronal input, leading to cognitive decline,” says Mark Fromer, MD, an ophthalmologist with Lenox Hill Hospital in New York City who was not involved in the investigation. “Cataracts may result in social isolation and a decline in cognitive stimulation. Although further work needs to be done, it is fairly evident that reducing sensory perception can lead to an earlier onset of dementia, and addressing these issues can have a significant effect on delaying dementia.”
For this research, Cecilia S. Lee, MD, the director of clinical research in the department of ophthalmology at the University of Washington in Seattle, led a team who analyzed health data from 3,038 adults age 65 and older with cataracts who were enrolled in the Adult Changes in Thought study, which has been tracking Seattle-area seniors since 1994. The average participant was 74, women made up 59 percent, and 91 percent identified their race as white.
Study subjects had received a diagnosis of cataract before the onset of dementia and had at least one study visit after cataract diagnosis. At enrollment and during visits, participants received standardized cognitive screening tests, brief physical evaluations, and medical history and risk factor assessments.
During the follow-up period, which averaged nearly eight years per person, about half underwent cataract extraction. A total of 853 individuals were diagnosed with some form of dementia, and 709 were identified as having Alzheimer’s disease.
Dr. Lee and her colleagues found that the risk of dementia was almost a third higher in patients who did not have cataract surgery.
“Given the substantial degree by which cataract extraction is associated with lower risk of dementia and its persistent effect beyond 10 years, the improvement in quality of life for the affected individuals and their family is likely considerable,” concluded the authors. “Further studies on the mechanisms by which cataract extraction may affect dementia risk are warranted.”
The scientists also evaluated dementia outcomes in study participants with glaucoma, a condition that causes increased pressure within the eyeball. They discovered that the risk of dementia did not differ between participants who did or did not undergo glaucoma surgery, which does not restore vision.
By Don Rauf Reviewed: December 13, 2021