Retina a brain health marker?

Microvascular abnormalities in the retina (ie, retinopathy*) may signify greater risks of neurologic disorders such as stroke and dementia, with more severe retinopathy conferring a higher mortality risk, according to data presented at ISC 2021.

“Impaired microvascular brain health is a rising public health concern [that] is associated with stroke and dementia. This is partly due to the [lack of] screening tools for preclinical risk stratification [and] direct clinical imaging tools for [the brain microvasculature],” said Dr Michelle Lin from Mayo Clinic, Jacksonville, Florida, US, who presented the findings.

“[Our results suggest that] the retina may serve as a tissue biomarker in interventional trials for cerebrovascular and neurodegenerative diseases,” said Lin.

Using the US National Health And Nutrition Examination Survey (NHANES) database, the team analysed data of 5,543 individuals (mean age 56 years) with evaluable retinal imaging (2005-2006 and 2007-2008 data, wherein retinal photographs were obtained). Of these, 696 individuals had retinopathy (45 percent women), 289 had stroke, and 597 had dementia. The NHANES data were linked to the National Death Index 2015 database. Median follow-up was 118 months (~10 years). [ISC 2021, abstract 8; Stroke 2021;52:A8]

After adjusting for demographic and vascular risk factors**, retinopathy was associated with higher risks of stroke (adjusted odds ratio [adjOR], 1.6, 95 percent confidence interval [CI], 0.95–2.7; p=0.077) and dementia (adjOR, 1.5, 95 percent CI, 1.1–2.1; p=0.024).

A dose-dependent association was observed between the severity of retinopathy and adjusted cumulative all-cause mortality (p_trend=0.021) – as the retinopathy worsens, so does the risk of death (adjusted hazard ratio [adjHR], 1.5; p=0.013 [Grade*** 1], adjHR, 2.4; p=0.038 [Grade 2], and adjHR, 3.4; p=0.204 [Grade 3].

A glimpse into brain health

However, despite the large, nationally representative sample, as well as the long follow-up period, data were obtained through cross-sectional self-reporting which, according to Lin, may have influenced the findings.

Nonetheless, the results underscore the value of retinal imaging in a neurologic context. “Retinal imaging allows direct visualization of small vessels and neuronal tissue, [and] is fast, low-cost, and portable,” explained Lin. “Retinal features may … [give] us a glimpse into microvascular brain health.”

Moreover, the transition from traditional bulky retinal imaging equipment to newer easy-to-use smartphone applications may facilitate retinal imaging even in underserved settings, she added. “[We may now be able to] screen for cerebrovascular disease even before a patient becomes symptomatic.”