Association between diabetic retinopathy and incident cognitive impairment

Abstract

Purpose : The relationship between diabetic retinopathy (DR) and cognitive impairment (CI) is unclear due to previous equivocal findings of limited cross-sectional studies and a lack of long-term data. In this study, we examined the longitudinal association between the severity of DR and the incidence of CI.

Methods : From the Singapore Epidemiology of Eye Diseases Study, a population-based cohort, we included 727 adults (201 Malays, 309 Indians and 217 Chinese; mean age [SD]: 66.9 [5.5] years; 44.9% female) with diabetes, gradable retinal photographs, no CI at baseline (2004-2011) and relevant data at follow-up (2010-2016). DR, graded from 2-field retinal photographs using the modified Airlie House classification system, was categorized as none, minimal/mild, and moderate or worse DR. CI was first assessed using the validated Abbreviated Mental Test (AMT); defined as scores of ≤6 and ≤8 for those with 0-6 and >6 years of formal education, respectively. The reliability of those with a positive CI screening on the AMT was subsequently confirmed with a clinical examination which included blood investigations, neuropsychological testing and magnetic resonance imaging. Incident CI was defined as having no CI at baseline but present at follow-up. Multivariable logistic regression models were used to study the association between the severity of DR and incident CI. Models were adjusted for age, gender and other risk factors for CI, including better eye presenting visual acuity.

Results : Of the 727 participants, 150 (20.6%) and 59 (8.1%) had minimal or mild and moderate or worse DR at baseline, respectively. At follow-up, 41 of 727 participants (5.6%) had incident CI using the AMT screening test, all of which were clinically confirmed. Compared to those with no DR, those with any DR had more than two-fold increased odds of incident CI (odds ratio (OR)=2.20, 95% confidence interval (CI) 1.07-4.52). Individuals with more severe DR also had a higher likelihood of developing CI, particularly those with moderate or worse DR (OR=3.41, 95%CI 1.15-10.10, P-trend=0.015, compared to those with no DR).

Conclusions : The presence and severity of DR increases the risk of developing CI several folds, independent of vision. These findings suggest that incorporating strategies to prevent the development and progression of DR may reduce the onset of CI in people with diabetes.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.