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.

Could nicotine possibly be good for you?

Short answer: Yes… sort of, and a new study shows again how the most addictive ingredient in cigarettes could help boost the brain.

But don’t start smoking — because trust me, any “benefits” of nicotine are far outweighed by the risks.

In the new study, researchers didn’t even look at smokers. They recruited 67 non-smokers with mild cognitive impairment, one of the earliest warning signs of dementia, and assigned them to wear either a nicotine patch or a placebo patch.

After six months, those who had the real patch did a little better on cognitive tests than those who got the placebo — and didn’t show any signs of side effects or even addiction.

It’s not too surprising, since nicotine is known to mimic a common neurotransmitter that often goes missing in people with dementia and other cognitive disorders.

It does such a good job of it, in fact, that it pretty much behaves exactly like that neurotransmitter once it’s in the brain — and it’s one of the reasons smokers get a quick boost in concentration after they light up.

These brain-boosting benefits are among the reasons Big Pharma has been hard at work on a nicotine pill — not to help smokers quit, but to bring the supposed benefits of nicotine to nonsmokers.

But no matter how they try to sell you that nicotine, whether it’s in a pill, patch or pipe, it’s just not worth it — because there are far better and more effective ways to boost your brainpower and slash your risk of dementia.

Start with the ordinary B vitamins you can get from any vitamin shop. One recent groundbreaking study found that seniors who were given a blend of B6, B12 and folate did 70 percent better on memory tests than seniors who took a placebo.

In fact, seniors who took the supplement improved by just about every measure, with boosts in episodic memory, semantic memory and overall global cognition. They even had lower levels of homocysteine, an inflammation marker linked to dementia, heart disease and more.

And along with memory, B vitamins can help with everything from mood to muscle.

With benefits like that, why mess around with nicotine?

There may “B” an answer to Alzheimer’s after all–and it might even be something you’re taking right now.

Researchers have found that high levels of three common B vitamins can dramatically slash the brain shrinkage associated with dementia and related conditions.

Naturally, they’re already hoping to sell this to you as a “drug,” but you don’t have to wait for Big Pharma’s blessing–because the ingredients are sitting on the shelf at your local vitamin store right now, and I’ll tell you all about them in a moment.

But first, let’s take a look at this remarkable new study.

Researchers recruited 168 seniors who suffered from mild cognitive impairment and assigned them to either a placebo or TrioBe Plus–a patented blend of vitamin B6, vitamin B12 and folic acid.

After two years, MRI scans revealed that those who had been taking the B vitamin blend had a much slower rate of brain shrinkage: .76 percent of volume per year, versus 1.08 percent in those who were given the placebo, or a difference of 30 percent.

What’s more, patients with the highest blood levels of the inflammation marker homocysteine at the start of the study had a 53 percent reduction in the shrinkage rate, according to the study in PLoS One.

By the way, here’s a humbling piece of trivia: All of our brains are shrinking. Even the healthiest ones lose about half a percent each year. Just a guess, but they may end up in the same place as keys, wallets and left socks.

Now, before you run off to try to slow your own shrinkage with some B vitamins, the researchers behind this study have a warning: Their blend, they say, is a high-dose “drug” and should only be given under the care of a doctor.

But that sounds a lot like patent-protecting greed to me, because one look at the TrioBe Plus ingredients label reveals that these high doses aren’t so high after all: 800 micrograms of folate, 500 micrograms of B12 and 20 milligrams of B6.

They’re high levels in that they exceed the U.S. government’s lowball recommended daily intakes… but not so high that they can’t be found without a prescription. In fact, you can pick them up at almost any supermarket or health food story in those exact amounts.

Since your own needs could vary depending on your age and condition, talk to a naturopathic physician about the best ways to add some B to your regimen now–but don’t be afraid to do it.

And don’t be afraid to start today–before your brain shrinks even more than it already has.

Dementia doesn’t have to come with the territory as you get older–and three new studies show how good habits for your body now can save your mind years later.

And it comes down to three things that should be a big part of your life anyway: vitamin D, tea and exercise, according to the studies presented at a recent Alzheimer’s Association International Conference held in Honolulu.

Let’s start with exercise.

Researchers tracked 1,200 elderly people for 20 years as part of a study on cardiovascular risk. But the researchers also noticed that the 242 patients in the study who developed dementia tended to have something in common: more time on the sofa.

Once they crunched the numbers, the researchers found that the patients who enjoyed the highest levels of physical activity had a 40 percent lower risk for dementia in any form. Those who moved the least, on the other hand, were 45 percent more likely to come down with the mind-robbing condition.

Maybe these folks should have been drinking more tea–because another new study on seniors finds that those who sipped between one and four cups each week had a 37 percent lower risk of dementia than those who drank no tea.

The researchers say coffee didn’t show any benefits except at very high levels of consumption… but don’t let that keep you from your daily cup of mud, because other studies have found that caffeine can slow the production of amyloid-beta, an amino acid found in the brains of Alzheimer’s patients. (Read, “Drink to beat dementia.”)

And in the third new study, researchers confirm something I’ve told you about before: Vitamin D can lower your risk of dementia–and a D deficiency can increase it dramatically. (Read, “Vitamin D can beat cognitive decline.”)

Researchers looked at data on 3,325 American seniors and found that those who had low levels of D were 42 percent more likely to suffer from cognitive impairment.

But wait–this one gets even worse. Those who were severely deficient in D had a 394 percent increased risk. And millions of us are severely deficient in D.

You might even be one of them.

But you can kill two birds with one stone here by getting a little exercise out under the sun, where your body can make its own vitamin D as you work up a sweat, burn some calories and get your blood pumping.

In addition to slashing your risk of dementia, that all-natural vitamin D can also keep your bones strong and lower your risk for any number of diseases, including diabetes and cancer. It may also boost your immune system, and it could even help you live longer.

Then, after a little exercise and a little sun, complete the trifecta by kicking back with a cup of antioxidant-rich tea. Green tea in particular has been linked to everything from longevity to cancer prevention.