Cataract Extraction May Reduce Dementia Risk

Cataract extraction is associated with decreased risk of developing dementia, researchers found in a study published in JAMA Internal Medicine.

Previous research on the association between cataract extraction and cognitive impairment or dementia has produced contrasting findings and the studies have not accounted for healthy patient bias, according to the study. This is the first study to compare the association between cataract extraction and dementia with other ophthalmic surgical procedures.

Researchers analyzed data from the Adult Changes in Thought (ACT) population-based prospective cohort study. That study involves older adults who undergo cognitive screening tests, physical exams, and assessments of medical history and risk factors. Follow-up extends until the development of dementia.

The current study limited its sample to the 3038 participants (aged 74.4±6.2 years, 59% women, 91% White) with APOE genotype data who were diagnosed with cataract before the onset of dementia. Of those participants, 1382 underwent cataract extraction, 853 developed incident dementia, and 709 developed incident AD dementia in the mean follow-up of 7.8±5.1 years.

Cataract extraction was linked with a lower adjusted risk of dementia (HR 0.71 P <.001), especially during the first 5 years after cataract surgery (HR 0.68 P <.001 later years HR 0.76 P =.02). The association was weaker than that of not having an APOE e4 allele but stronger than associations with White race, sex, and smoking history.

The adjusted HR for dementia decreased when the researchers removed the 1994 to 1996 cohort from their analysis (0.52 P <.001) and when they counted the first 2 years after cataract surgery as unexposed person-time for the development of dementia (HR 0.57 P <.001).

HR estimates did not substantially change when the researchers included confounding variables, adjusted for health care utilization rates, accounted for healthy patient bias, only included participants with incident cataracts, controlled for Cognitive Abilities Screening Instrument (CASI) score at time of cataract diagnosis, or adjusted the recent vs established surgery thresholds.

Among patients (n=728) who were diagnosed with glaucoma, glaucoma surgery was not associated with decreased risk of dementia (HR 1.08 P =.68).

“These results have implications for the care of older persons who are uniquely at higher risk for both impaired vision due to cataract and impaired cognition due to neurodegeneration observed in age-related dementia,” according to the researchers. “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.”

Limitations of the study included basing cataract diagnosis and surgery on diagnosis and procedure codes in electronic medical records, lack of clinical data, possibility of coding errors, reverse causation and generalization to non-White populations.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

Reference

Lee CS, Gibbons LE, Lee AY, et al. Association between cataract extraction and development of dementia. JAMA Intern Med. Published online December 6, 2021. doi:10.1001/jamainternmed.2021.6990