Comorbidity of dementia and age-related macular degeneration calls for clinical awareness: a meta-analysis.

Aim: To determine the association between dementia and age-related macular degeneration (AMD) using meta-analysis.

Methods: We searched in the MEDLINE, EMBASE, Web of Knowledge, PsycInfo and Cochrane database of systematic reviews for studies published from March 1959 to March 2018. We included cross-sectional, case-control and cohort studies that evaluated the association of dementia/Alzheimer's disease (AD) with AMD (as outcome) and the association of AMD with dementia/AD (as outcome). Studies that compared cognitive functions between AMD and controls were also included. The summary outcomes, namely odds ratio (OR), relative risk, mean differences and corresponding 95% CIs, were estimated using random effects models. We performed sensitivity analysis based on study quality and individual study effect to control for potential biases.

Results: Among 2159 citation records, we identified 21 studies consisting of 7 876 499 study subjects for meta-analysis. Patients with dementia (p≤0.017, OR≥1.24, I≤9%) or AD (p=0.001, OR=2.22, I=50%) were at risk for AMD, particularly for late AMD (p<0.001, OR=1.37, I=0). AMD was also significantly associated with increased risk of AD/cognitive impairment (p=0.037, OR=2.42, I=38%). Moreover, patients with AMD had poorer cognitive functions when compared with controls, including Mini-Mental State Examination (p<0.001, I≤79%) and Trail Making Test A (p<0.001, I=0). Sensitivity analysis and Egger's test indicated our results were less likely biased.

Conclusions: A significant association between dementia/AD and AMD calls for greater clinical awareness. The cost-effectiveness of routine screening for the other condition in patients with primary diagnosis of dementia/AD or AMD requires further study.