When I get a patient facing depression, one of the first things I do — before I run a single test — is ask what they’ve been eating.

And most of the time, the answer to that question tells me everything I need to know — because people who eat garbage usually end up with a mood down in the dumps.

This food-mood connection has been proven time and again. And now, a new study out of Europe on nearly 9,000 people finds that a steady junk-food habit can boost your risk of depression by up to 51 percent.

The two specific categories with the strongest links to depression were fast food like burgers and pizza and processed pastries such as donuts and croissants.

It didn’t take much, either, because the researchers say patients with even a moderate junk habit had a higher risk of depression than those who ate better foods.

The only flaw here is that the consumption levels were tracked using a food frequency questionnaire — a fairly weak form of research that relies on people to recall not only what they ate, but how much and how often they ate it.

And, as you might imagine, people have a tendency to lie on those things to make it seem like they have better habits than they really do.

Still, there’s something to this — because it’s been proven by stronger studies, and it’s not hard to see why. Junk food is completely lacking in the nutrients your body needs to function… especially your brain.

What’s more, empty carbs can cause your sugar levels to fluctuate wildly — elevating your mood briefly, and then bringing it crashing back down.

And let’s not forget that many people have hidden or undiagnosed food sensitivities that cause or worsen depression and other mood disorders — and the ingredients and chemicals used in junk food are often the culprit.

Junk in the diet also creates body fat — and excess body fat can cause your hormones to go haywire. And yes, hormonal imbalances are also a major cause of depression.

I’ve found that any number of supposedly mental disorders can be cured, or at least dramatically improved, through better diet — including depression, anxiety, and ADHD.

From food to drink — I’ve got something brewing next that you definitely want to see. Keep reading!

I always get a kick out of the fridge in my local 7-11. It’s loaded with drinks that make all kinds of promises.

Energy is the most common one, of course, but others promise everything from “focus” to “calm” to “concentration.”

It’s a laugh, because no matter what promise they make, most of these drinks have the same basic ingredients: sugar, water, and artificial flavors combined with small amounts of vitamins or large amounts of caffeine.

In some cases, those vitamins can deliver on the promise made by the label — just not in the tiny amounts you’ll find in the drink. You’re always better off just taking it as a supplement.

And in at least one case, you don’t need to swallow a thing — drink or supplement — to get the benefits.

Rosemary, the fragrant herb often used in soups and meat dishes, is so good at helping you to focus that just the scent alone will do the trick.

Twenty people were given a whiff of rosemary followed by a series of cognitive tests and mood assessments. The stronger the smell, the better they did on both — although the impact on mood was nothing compared to what it did for cognition.

Believe it or not, that’s not even the surprise here. Other studies have also shown that the very smell of rosemary can give your mind an extra gear.

No, the real surprise is that blood tests revealed the presence of 1,8-cineole in the blood. That’s the essential oil found in rosemary, somehow turning up in blood after inhaling the mere odor of this stuff.

The researchers say that means the aroma alone acts as a “therapeutic drug” and are already talking of how they might one day make meds out of fragrant herbs such as rosemary, peppermint, and lavender.

But why wait for meds and their inevitable side effects when you can go straight to the source?

Rosemary is available right now, for cheap, and if I was in college I’d be practically stuffing it up my nose at test time.

Might sound crazy, but a better grade is a better grade.

Since my test-taking years ended long ago, I plan to use rosemary differently — like next time I need help finishing a Sudoku puzzle or locating missing socks.

It almost sounds like the benefits of some promising new blockbuster drug: Just a little bit can help lift mood, concentration and energy levels — with virtually no side effects.

Well, there is one side effect: You might need to pee a little more.

Of course, this isn’t some experimental new drug — just plain old water, and new research shows how letting yourself run dry can throw your whole day out of whack.

In a set of three experiments, 25 healthy young women were given either enough H20 to keep hydrated or brought just below their optimal levels with exercise and diuretics.

By “just below” I mean really just below — they were missing only between 1 and 2 percent of their needed water. But those small changes led to big differences as these women suffered from measurable dips in mood and focus and were more likely to feel fatigue and suffer headaches.

Although the study didn’t look at men, there’s no reason to think mild dehydration would affect them any differently.

In other words, you need your water — but don’t get carried away.

You know the old saying about drinking eight 8-ounce glasses a day? Forget it. It’s never been proven by science (although the bottled water companies would like you to think otherwise).

In fact, too much water can be even worse for you than too little.

The only time you need to whet your whistle is when you feel thirsty — and despite what you’ve heard, it doesn’t have to be plain old water.

Coffee and tea, for example, are just fine. Both of them are mildly diuretic, but they’ll still leave you with a net gain of water and keep you hydrated.

Just one warning here: Water may not be a drug on its own… but there’s a good chance there are drugs in your water.

U.S. water standards are plunging like a barrel over Niagara Falls. Hormones, sex meds, antibiotics and more are regularly turning up in our drinking water — and in some places, you can add illegal drugs, rocket fuel and toxic waste to the list.

Even in trace amounts, do you really want to drink that?

Drink only filtered water. You don’t have to shell out big money on bottled year after year if you invest in a quality reverse osmosis system for your home.

Senior moments aren’t just for seniors anymore.

Anyone can have a brain hiccup no matter how old or young they are — but the latest research shows that the cognitive slide we usually associate with aging actually begins earlier than anyone would have thought.

Much earlier.

And if you’re in your 40s, I got some bad news for you: Your brain may have already passed its peak, and it’s not getting any better from here unless you do something about it.

More on that in a moment — but first, the study that’s going to be hard to forget: A look at data on 5,200 men and 2,200 women who took part in the Whitehall II study of British civil servants finds that people begin a noticeable cognitive slide at the age of 45.

Over a 10-year period, men and women alike who were between 45 and 50 at the start of the study saw declines in every category except vocabulary, with an average drop of 3.6 percent in overall mental ability.

Men between 45 and 50 also experienced a 4 percent dip in reasoning and thinking skills during that 10-year period, while women saw a decline closer to 5 percent.

Obviously, older volunteers had even bigger drops — senior men suffered a 10 percent loss in thinking and reasoning, while senior women lost about 8 percent.

But the fact that younger people experienced any decline at all should be a wake-up call to take the actions now that can save your brain later — and that action should start with the simple B vitamins available at any health food store.

The Bs help control the most essential parts of brain function, everything from mood to muscles to memory — and if you boost your intake now, you can protect all three… especially that memory.

Studies have shown that seniors at risk of cognitive decline can slow, stop and even reverse the slide by upping their levels of B6, B12, and folate — but as the new study shows, you don’t want to wait until you’re a senior to start getting your Bs.

Start today… no matter how old — or young — you are.