Daniel Amen wants to get inside your head. The 57-year-old psychiatrist, who’s spent more than 20 years studying brain scans, has used the research collected at his four Amen Clinics (including one in Reston, Va.) to create a program designed to keep you looking, feeling and — most importantly — thinking younger. In “Use Your Brain to Change Your Age” ($26, Crown Archetype), he explains why improving your diet; limiting alcohol and caffeine; increasing your physical activity; getting enough sleep; reducing stress; and constantly learning are noggin-boosting habits.

When you say use your brain to change your age, you’re not just talking about the power of positive thinking.
You can do positive thinking all day long, but if you’re overweight and have diabetes or hypertension and you’re not exercising and not really thinking about your brain, then you’re in trouble. And you won’t be thinking positively.

How does being overweight affect your brain?
It’s really quite terrifying. We published two studies last year that showed that as your weight went up, the function of your prefrontal cortex went down. The prefrontal cortex is the front third of the brain that’s involved with things like judgment, forethought, impulse control, organization and planning. Two-thirds of our country is overweight. We should really take this crisis in obesity very seriously because it’s going to lead to a crisis of brain health.

Why is it so easy for us to make excuses for eating poorly or drinking too much alcohol?
Because we don’t care about our brains. When you get up in the morning and look in the mirror, you go, “Hmmm. I don’t like how that looks.” You can do something to change it: Comb your hair, put on skin cream, whatever. Nobody looks at their brain, and because they don’t look at it, they don’t think about it.

But if we can change our brains, lapses aren’t so bad, right?
You can literally improve how it functions. We looked at 115 active and retired football players. As a group, their brains were terrible. But on our program, their brains got better. If you rehabilitate these brains, there’s less depression, less dementia, and if we can rehabilitate NFL players who’ve been hit in the head 30,000 times, then let’s work on soldiers and the 2 million people who have car accidents every year.

So all is not lost.
All is not lost, but the sooner you start, the better.

What’s the No. 1 thing people should do for their brains?
Before you do anything, ask yourself, “Is this good for my brain or bad for my brain?” And know the lists of things to avoid and things to do. Just ask yourself that one question and it will be the start of a great relationship with your brain.