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.

There are plenty of places on the body where you definitely don’t want fat building up.

Hello, gut.

But there’s one place you want as fat as can be, and that’s right inside your skull. Your brain is actually 60 percent fat — and the most critical fats of all when it comes to brain health are the omega-3 fatty acids found in fish oil.

Now, a new study confirms just how important those fats are for your thinker: People with the lowest levels have aging, shrinking brains and problems remembering what they had for breakfast.

Since the most prominent fat in your brain is DHA, the study of 1,575 dementia-free seniors also finds that it’s the most important one for brain health. The 25 percent with the lowest blood levels of DHA had the smallest brain volumes.

And, yes — when it comes to brains, bigger is definitely better.

Younger is better, too. And while you can’t turn back the clock, your brain can get old before its time — and seniors with the lowest DHA levels had brains that seemed two years older, according to the study in Neurology.

That’s what’s going on inside the head.

Out in the real world, seniors with the lowest omega-3 levels did worse on just about every test thrown their way — including tests on visual memory as well as executive functions such as problem-solving, multitasking, and abstract thought.

Along with charging your thinking cap, omega-3 fatty acids can also help slash your risk of heart problems, stroke, macular degeneration, and more. They can even lower your risk of gum disease.

But let’s stick to the brain today.

In addition to those omega-3s, be sure to get plenty of B vitamins. Studies have shown that seniors who get high levels of B6, B12 and folate have bigger brains, better memory, and more overall protection from dementia’s top risk factors.

You can read more about that B vitamin and dementia link right here.

Meats tend to be richest in B vitamins, but the best way to get what your brain needs is with a quality B complex from a trusted vitamin maker.

Similarly, you can get omega-3 fatty acids from a diet rich in fatty fish — but since most people don’t eat nearly enough salmon, herring, and anchovies, add an omega-3 supplement to your shopping list if you’re not taking one already.

For one more way to power up your grey matter, keep reading.

You probably don’t spend much time at all thinking about how fast you walk or how strong your grip is.

But maybe you should — because a new study shows how these basic tests could help predict serious health problems years down the road.

Researchers from the Boston Medical Center measured the grip strength, walking speeds and cognitive function of more than 2,400 people with an average age of 62, and then tracked them for an average of 11 years.

They found that the slowest-walking volunteers who were middle aged at the start of the study were 50 percent more likely to face dementia 11 years later than faster walkers.

Slower walkers also had less overall brain volume — another dementia warning sign — and did worse on memory, language and decision-making tests, according to research presented at the annual meeting of the American Academy of Neurology.

That should be enough to make you want to pick up the pace as you walk — and while you’re at it, you might want to work on a firmer handshake, too: The study also found that people with a stronger grip at the age of 65 had a 42 percent lower risk of a stroke or mini stroke than those with weaker grips.

That strong grip was also linked to larger brain volume and better performance on some cognitive tests.

It’s not the first study to link the telltale signs of frailty to poor health. One study from just a few months back found that people who walk the slowest have a much higher risk of an early death. Other studies have found that slower walkers are more likely to face heart attacks and other heart-related problems.

It’s not the walk or grip itself that’s causing any of this, of course. These conditions are often the subtle early warning signs of physical or neurological problems — and it might not always be obvious even to yourself when you’ve lost a step or two or let loose on your grip.

But if you find yourself lagging behind your friends or you don’t quite feel the power you used to, don’t ignore it. Get yourself checked out now so you don’t have to face these other problems later.

We waste a fortune on tests we don’t need for conditions we don’t have — conditions we often shouldn’t be worrying about in the first place.

All those unnecessary cancer screenings come to mind.

But there’s one disease you should worry about, especially if you’re getting up there in years — and now, there’s an easy test you can take that won’t cost a dime, eat up much time, or require even a drop of your blood.

It’s a simple quiz for Alzheimer’s disease. The only catch here is that you don’t take it yourself — someone you love takes it for you.

The 21 questions on memory and behavior range from the more minor issues, like forgetting what day it is, to the more troubling signs of serious memory loss — like mixing up family members and the inability to recognize friends.

You can see a whole version of the quiz on the website of the Daily Mail.

The questions are worth one or two points apiece, and anyone who scores more than 15 out of a possible 27 either has…or is at high risk for…Alzheimer’s. I don’t doubt that, either — you’d have to be missing out on quite a bit to reach 15 points on this test.

It’s a lot easier to hit the five points that supposedly indicate mild cognitive impairment — and if that’s you, don’t worry too much. Some of the questions hit on struggles that even many healthy people face — like problems calculating tips or operating the remote control.

I gave the quiz to a few friends, and most of them were at or near that five-point mark…so either everyone I know is suffering from cognitive impairment, or the bar for that one was set a little too low.

In any case, even hitting the high numbers isn’t a surefire sign of Alzheimer’s — because in too many cases, dementia-like symptoms can be caused by something else entirely: medication.

So before you add one more drug to the list — an Alzheimer’s drug — work with a naturopathic physician on getting off the pills you don’t need and onto natural alternatives for the ones you do.

For many people, simply reducing or eliminating meds will make a night-and-day difference.

In addition, be sure to add a B complex to your supplement regimen. B vitamins can stop or even reverse memory loss if you already have it — and, more importantly, keep it at bay if you don’t.