Retinal vein occlusion (RVO) is significantly associated with increased risk for Alzheimer disease (AD), vascular dementia (VD), and all-cause dementia, according to a study published in the American Journal of Ophthalmology.
In this retrospective, population-based cohort study, researchers analyzed records for patients aged 63.4±10.1 years who had been diagnosed with RVO prior to being diagnosed with dementia (N=46,259). Age- and sex-matched comparison patients with corresponding levels of systolic blood pressure composed the comparison group (n=138,777). Researchers monitored all patients for development of dementia (mean follow-up duration was 6.6±1.4 years). Demographic and lifestyle data were collected through self-reported standardized questionnaires that included smoking status (non-smokers, ex-smokers, or current smokers), alcohol intake (≥30 g/day was defined as heavy drinking), and physical activity (weekly frequency of ≥20 minutes of strenuous exercise ≥3 times/week or ≥30 minutes of moderate exercise ≥5 times/week). Baseline comorbidities were identified based on past medical history, health examination results, or prescription codes.
During the mean follow-up duration of 6.6 years, there were 14,727 cases of all-cause dementia (10,965 AD and 1788 VD). The group of individuals with RVO had increased risk for subsequent all-cause dementia (hazard ratio [HR] 1.18; 95% CI, 1.14-1.23), AD (HR 1.17; 95% CI, 1.12-1.22), and VD (HR 1.29; 95% CI, 1.17-1.43) in unadjusted analysis. Associations of RVO with all-cause dementia (HR 1.16; 95% CI, 1.12-1.21), AD (HR 1.15; 95% CI, 1.11-1.20), and VD (HR 1.24; 95% CI, 1.12-1.37) persisted after adjusting for confounding variables, including demographic and lifestyle variables and comorbidities. A 1.31-fold increased risk for all-cause dementia was found for individuals with both RVO and hypertension (95% CI, 1.25-1.37).
Limitations of this study include possible inaccurate diagnoses of RVO, dementia, and other comorbidities; RVO incidence may have been underestimated due to the inability to identify asymptomatic cases. The categorization of subgroups of RVO and dementia was limited because of difficulty assessing the diagnostic codes. Due to the retrospective design of the study, researchers cannot confirm a causal relationship. Selection bias is possible because a medical claim-based comparison group was used.
The researchers indicated that epidemiologic evidence of the association between RVO and increased risk for all-cause dementia, which suggests clinical implications for the role of RVO in the development of dementia. “Given that the eye shares many neural and vascular similarities to the brain, the eye may offer a direct window to cerebral pathology and is suspected to contain biomarkers for AD,” the authors said. “Furthermore, the eye is very accessible, relatively inexpensive to examine, and the retina can be easily imaged; therefore, ocular biomarkers are attractive.”
Nam GE, Han K, Park SH, Cho KH, Song SJ. Retinal vein occlusion and the risk of dementia: A nationwide cohort study. Am J Ophthalmol. [published online August 7, 2020]. doi: 10.1016/j.ajo.2020.07.050