Cataract Surgery May Lower Dementia Risk in Older Adults

Older adults who underwent cataract surgery had nearly a 30% lower risk of subsequently developing dementia compared with older adults who did not undergo the surgery, a study in JAMA Internal Medicine has found. A similar benefit was not observed among adults who underwent glaucoma surgery—a procedure that does not restore vision loss.

“Adults who had [cataract] surgery had lower dementia risk more than a decade after their procedure,” said lead study author Cecilia S. Lee, M.D., M.S., the Klorfine Family Associate Professor of Ophthalmology at the University of Washington (UW) and the Karalis Johnson Retina Center. “These findings suggest timely extraction of cataracts could significantly improve the quality of life for older adults as well as their caretakers.”

Lee and colleagues assessed data from the Adult Changes in Thought (ACT) study, an ongoing longitudinal study initiated in 1994 by UW and Kaiser Permanente Washington. The ACT study recruits adults 65 and older from the Kaiser Permanente Washington membership who do not have dementia and follows their cognitive outcomes. The researchers looked at the outcomes of 3,038 adults who received a cataract diagnosis before the onset of any dementia (the diagnosis could be before or after the person enrolled in the ACT study). Of this group, 1,382 adults underwent cataract surgery and 1,656 did not.

In total, 853 of these ACT participants developed dementia during the study follow-up period (average of 8 years per patient). After adjusting for numerous health variables (including smoking status, diabetes, hypertension, and body weight), the researchers found that adults who underwent cataract surgery had a 29% reduced risk of dementia compared with those who did not have cataract surgery.

Lee told Psychiatric News that she expected cataract surgery would be associated with lower dementia risk but was surprised by the extent of this protective association. The 29% reduction was greater than the protection offered by higher education, not smoking, or sex/racial background.

“Naturally, the next step was to try and disprove these findings,” she said.

The researchers began by excluding from their analysis all participants who enrolled in the earliest years of ACT (1994-1996), as this group had the shortest medical history (Kaiser began implementing electronic health records in 1993); this did not change the results. They also ran an analysis excluding all patients who developed cataracts prior to enrolling in ACT, and this did not change the results. Next, the team excluded all participants who had two years or less follow-up after cataract surgery to remove possible cases of undiagnosed dementia; this led to an even greater protective effect—43% reduced risk of dementia compared with those who did not have cataract surgery.

Finally, Lee and colleagues did a comparative risk assessment using data from 728 ACT participants who received a glaucoma diagnosis and opted for or against surgery. This analysis was done to determine if healthy patient bias might be influencing the cataract risk findings; that is, seniors who opt for eye surgery are healthier than those who do not and thus less at risk for dementia. “It’s not quite an apples-to-apples comparison, but both glaucoma and cataract surgeries are outpatient procedures that require someone to be relatively healthy,” Lee said. “The main difference is glaucoma surgery can slow down or even halt vision loss, but it does not improve or restore any sight.”

The researchers found no evidence that glaucoma surgery reduced the risk of subsequent dementia in this population.

Lee told Psychiatric News that multiple reasons may explain why cataract surgery might reduce dementia risk. Sensory impairments can create challenges for the brain, like circadian clock disruptions. There are also the psychosocial benefits of restored vision—less social isolation and the ability to once again drive or participate in activities. “But I believe there is a neurological link as well,” she added. “The retina is derived from the same neural tissue as the brain, and problems in the eye could be a strong reflection of what’s going on in the brain.”

This study was supported by grants from the National Eye Institute and the National Institute on Aging, along with an Alzheimer’s Drug Discovery Foundation Diagnostics Accelerator Award, Latham Vision Innovation Award, and a grant from Research to Prevent Blindness. ■

“Association Between Cataract Extraction and Development of Dementia,” is posted here.