Increased risk of Parkinson's disease in cataract patients: a population-based cohort study

The purpose of this study was to investigate whether there is an association between cataracts and Parkinson's disease in Taiwan.

A retrospective cohort study was conducted to analyze the database of the Taiwan National Health Insurance Program from 1999 to 2002. This study consisted of 26,031 individuals aged 40-84 years with newly diagnosed cataracts as the cataract group and 25,937 randomly selected individuals without cataracts as the non-cataract group. Both groups were matched for sex, age and index year of diagnosing cataracts. The incidence of Parkinson's disease by the end of 2011 and the association of Parkinson's disease with cataracts and other comorbidities were measured.

The overall incidence of Parkinson's disease was 1.48-fold higher in the cataract group than the non-cataract group (3.18 vs. 2.15 per 1000 person-years, crude HR 1.48, 95% CI 1.32, 1.66). After adjusting for confounding factors, the adjusted HR of Parkinson's disease was 1.26 (95% CI 1.12, 1.42) for the cataract group, when compared with the non-cataract group. Dementia (HR 2.72, 95% CI 1.92, 3.84), depression (HR 2.09, 95% CI 1.63, 2.66), hypertension (HR 1.42, 95% CI 1.26, 1.61), cerebrovascular disease (HR 1.32, 95% CI 1.07, 1.63) and age (every one year, HR 1.08, 95% CI 1.07, 1.09) were other factors significantly related to Parkinson's disease.

Overall, this study discloses a 26% increased hazard of Parkinson's disease in cataract patients. Further studies are required to investigate whether cataracts are one of non-motor manifestations of Parkinson's disease.