Age-Related Macular Degeneration and Risk of Degenerative Dementia among the Elderly in Taiwan: A Population-Based Cohort Study

Abstract

Purpose: To investigate the relationship between age-related macular degeneration (AMD) and future development of Alzheimer's disease (AD) or senile dementia.

Design: A longitudinal case-control study using the Taiwan National Health Insurance Research Database.

Participants: From 2001 to 2009, the newly diagnosed AMD cases aged ≥65 years in the database were recruited as the AMD cohort (n=4993). Of those, there were 540 with and 4453 without exudative AMD diagnoses. Subjects without any AMD, matched for age, gender, and time of enrollment, were randomly sampled as the control cohort (n=24,965) for comparison.

Methods: Alzheimer's disease/senile dementia-free survival analysis was assessed using a Kaplan-Meier method. Cox proportional hazard regressions were performed to calculate the hazard ratios (HR) of AD or senile dementia for the 2 cohorts after adjusting for preexisting comorbidities and number of clinical visits.

Main outcome measures: The first-ever diagnosis of AD or senile dementia during the observation period.

Results: Of the 29 958 sampled subjects, 1589 (5.3%) were diagnosed with AD or senile dementia during a mean follow-up period of 4.4 years, including 294 (5.9%) from the AMD cohort and 1295 (5.2%) from the control cohort. The incidence of AD or senile dementia was higher in patients with AMD than in the controls (P=0.044), with an HR of 1.44 (95% confidence interval [CI], 1.26-1.64) after adjusting for covariates. The stratified analysis showed that the adjusted HR for AD or senile dementia was 1.35 (95% CI, 0.89-2.06) for exudative AMD versus the controls and 1.44 (95% CI, 1.26-1.65) for nonexudative AMD versus the controls.

Conclusions: This study provides large-scale, population-based evidence that AMD, especially nonexudative AMD, is independently associated with an increased risk of subsequent AD or senile dementia development.