They say the eyes are the windows to the soul, but they may also offer a view into the brain. A new study suggests that a simple eye test could help diagnose the early stages of age-related cognitive decline.

Retinal degeneration has the same root as brain degeneration: vascular disease, also known as blood vessel damage. The idea is that it is a lot easier to look for vascular disease in the eye than in the brain.

The participants who had retinopathy performed worse on cognitive tests. They also had more areas of vascular damage in their brains.

To determine whether eye disease might predict brain disease, researchers at the University of California, San Francisco tested the eye health and cognitive functioning of over 500 female patients over the age of 65, who had taken part in the Women’s Health Initiative studies. Participants took tests once a year that measured thinking and memory function, over a period of ten years. Four years after the study began, the participants’ eye health was measured, and after another four years, their brains were scanned.

There was a solid link between retinopathy – damage to the retina – and brain health. The participants who had retinopathy performed worse on the cognitive tests. They also had more areas of vascular damage in their brains. In fact, the total amount of tissue that was damaged was 47% larger in women with retinopathy than women without. In some areas of the brain, the damaged area was up to 68% larger. The connection was still found after the researchers controlled for diabetes and blood pressure, both of which can lead to blood vessel damage in the eye and brain.

“Problems with the tiny blood vessels in the eye may be a sign that there are also problems with the blood vessels in the brain that can lead to cognitive problems,” concluded author Mary Haan in a university news release. Using simple clinical tools like eye tests could be a big help in predicting who might develop more significant diseases in the years to come. And catching diseases early always gives the best odds for treatment.

The study was published in the journal Neurology.