Impact of mental health comorbidities on the effect of cataract surgery on dementia risk: a real-world retrospective cohort study

Background Cataract surgery has been shown to reduce the risk of developing dementia in the future; however, its impact on different dementia subtypes, including vascular dementia, remains unknown. Moreover, its dementia-protecting effect among cataract patients with common mental disorder (CMD) remains unclear. Methods Patients aged 65 or older diagnosed with cataract between 2012 and 2021 were included and grouped based on whether they underwent cataract surgery within 1 year of diagnosis. Propensity-score matching was used to balance baseline characteristics, and Cox proportional hazards models were applied to assess dementia incidence within 5 years post-cataract between groups. Subgroup analyses were performed based on CMD status. Results After propensity-score matching, 75 757 patients were included in both surgery and control groups. Cataract surgery significantly reduced dementia risk (HR=0.677, 95% CI =0.638 to 0.719, p<0.001), particularly for Alzheimer’s disease (HR=0.643, 95% CI=0.576 to 0.716, p<0.001), with no significant effect on vascular dementia (HR=0.968, 95% CI=0.851 to 1.101, p=0.621). Subgroup analyses showed a significant reduction in dementia risk for patients without CMD (HR=0.666, 95% CI=0.624 to 0.710, p<0.001), but no protective effect in those with CMD, regardless of CMD status. Conclusion Cataract surgery is linked to a lower risk of dementia, especially Alzheimer’s disease, in patients with cataract. However, this protective effect is diminished in those with CMD. The data supporting this study are available from the corresponding author upon reasonable request.