Retina can help reveal brain health

The eyes are a window to the soul, but also to the brain. The health of easy-to-check blood vessels in the retina reflects the health of blood vessels deep inside the head, findings that raise the possibility of a simple eye exam catching early signs of brain trouble, scientists report in the March 27 Neurology.

“The potential is very great — to use the eye to diagnose what’s going on elsewhere in the body, particularly in the brain,” says neuroscientist Alistair Barber of Penn State College of Medicine in Hershey. “The retina is relatively easy to see. The brain is not.”

The findings add to the growing number of studies focusing on blood vessels that link eye and brain health. The Neurology study was conducted as part of the Women’s Health Initiative, which tracks the health of postmenopausal women. Over 10 years, researchers led by epidemiologist and biostatistician Mary Haan of the University of California, San Francisco looked for a link between eye disease and brain performance in 511 women who were at least 65 years old.

In the study, participants had their pupils dilated as researchers took pictures of their retinas. After careful examinations, 39 women, or 7.6 percent of the total, were found to have diseased blood vessels in the retina, a condition called retinopathy in which the vessels can become swollen, leaky or grow abnormally. Usually, retinopathy is a symptom of diabetes or high blood pressure, two disorders that if left untreated are known to affect brain functioning.

Over the decade of testing, women with retinopathy scored about 10 to 15 percent lower on questionnaires that tested brain functions such as memory, verbal fluency and writing than did women without the eye disease. What’s more, MRI scans revealed that women with retinopathy had more blood vessel damage in their brains — and also more areas of damage to brain tissue, possibly from tiny strokes.

“Vascular health has a direct effect on the brain, and you can see those developments when you look at the eye,” says Haan.

The study group was predominantly made up of Caucasian women. The link between eye and brain health might be stronger in other groups of people, particularly those who are at a higher risk for type 2 diabetes and high blood pressure, such as African Americans and Hispanics, Haan says.

Although the study spanned 10 years, it wasn’t designed to figure out whether eye disease shows up before brain problems. More studies are needed to clarify the timing of the two disorders. 

Neurologist and epidemiologist Rebecca Gottesman of Johns Hopkins University School of Medicine in Baltimore cautions that the findings don’t mean that everyone with retinopathy will develop brain problems. But the results emphasize the importance of blood vessel health for brains, she says. “It’s good to know the status of the blood vessels in a noninvasive way.”