Keep an eye on your eyes -- because your peepers just might be the first part of your body to spy dementia coming.

That's especially true if your eyes are getting an up-close look at retinopathy, an eye condition that often leads to vision loss and even blindness.

It's bad enough on its own, but now researchers say a new look at data on more than 500 women finds that dementia and retinopathy may come hand-in-hand -- or as close to hand-in-hand as brains and eyes can be, anyway.

Researchers say women given annual memory and thinking tests for up to a decade were much more likely to flunk them if they had the eye disease -- and that was true even if they had the blood vessel damage in the retina that marks the condition, but didn't have any actual vision problems yet.

Of course, that blood vessel damage isn't truly a disease all its own. Retinopathy is usually a warning of something else going on -- another condition that could be causing the same type of blood vessel damage in much less visible areas.

Like the brain.

And sure enough, brain scans of the women in the new study revealed that those who had the eye disease also had blood vessel damage inside the brain itself.

Obviously, the answer here isn't just treating the eyes. It's finding and treating the underlying condition before it's too late. Or better yet, avoiding the condition in the first place -- and that means taking care of the rest of your body, because one of the leading causes of retinopathy is diabetes.

In fact, the two conditions are so closely linked that diabetic retinopathy is now the leading cause of new blindness among middle-aged Americans -- and we know that diabetics are also more likely to suffer from dementia.

You've heard of killing two birds with one stone, right? Avoid diabetes, and you'll likely avoid three diseases (or more) at the same time.