John Ratey is near the top of my list of authors to whom I owe a debt of gratitude. He's coauthor of Driven to Distraction, the book that convinced me I have attention-deficit disorder. Getting my ADD diagnosed and treated is among the smartest things I've ever done in my life.

His new book is Spark: The Revolutionary New Science of Exercise and the Brain, which won't have that kind of impact on my life. I mean, if I'm not aware of the emerging research in this area, I'm not doing my job. Still, the book offers a terrific explanation of the science showing that exercise makes us smarter.

You can get a taste of the book from this L.A. Times interview with Dr. Ratey. Here he explains the book's big idea -- that exercise actually increases the stuff inside the brain that makes us smarter:

In the interview, he goes on to hit some of the highlights of the book's message:

• Intense exercise is better than easy exercise. So if you have a choice of doing more exercise at an easy pace, or less at a harder clip, it's better to work harder for a shorter time.
• Exercise that requires intense motor learning, such as dance or martial arts, is better than exercise in which your body does what it's already good at doing, like walking or jogging. (Side note: I wrote a story ages ago for Men's Health that touched on the same idea as it related to strength training, explaining why dumbbells make you smarter by forcing you to improve your balance and coordination, a benefit you wouldn't get from using machines.)
• Ratey believes it's better to exercise in the morning, since it gives you an attention-boosting benefit that can last much of the day. Over the years I've exercised at all times of the day -- early morning, lunchtime, evening -- and for me the midday workout is best. But Ratey's book makes a forceful argument for morning exercise, showing how it boosts the academic performance of struggling high school students.

He refers to one study from the early '90s that looked at exercise for women suffering symptoms of PMS. One group did endurance exercise, while a matched group "used weight machines for supervised strength training." Both groups saw some relief of physical symptoms, but the aerobics group got more psychological relief. In particular, Ratey writes, "the aerobic set showed a less pessimistic outlook and more interest in the world." I don't know about you, but if I had to suffer the double indignity of being supervised on top of having to use weight machines, I'd be pretty damned pessimistic, too.

Later in the book, he admits that there's a paucity of research into the ways strength training affects the brain, whether we're talking about intelligence, attention, or mood. A lot of the studies on exercise and brain function were conducted on rats, for two simple reasons: They love to exercise -- if you give them a wheel, they'll run in it without any coaxing -- and you can dissect them afterwards to see how their brains changed. You can't get rats to lift weights, and you can't dissect the brains of human lifters.

Some evidence suggests that strength training improves mood, boosts confidence, and reduces anxiety. But he also mentions a study suggesting that heavy lifting -- what I do and recommend in my books -- increases anxiety. He doesn't have a reference section in the book, so I couldn't look up that particular study to see who was recruited for it. If we're talking about inexperienced lifters, then of course I could see why lifting near-max weights would scare the shit out of them. No sane fitness professional would recommend using weights that heavy without a months-long buildup.

If you wanted to make a case for pumping up your brain while building up your strength and muscle mass, you'd have to do it by extrapolation. Ratey touches on recent research suggesting that chronic lifting produces measurable changes at the genetic level, which could in theory benefit brain function. More important is the effect that lifting and other intense, intermittent activities have on key hormones like IGF-1 and HGH. If you boost your body's growth factors, you're potentially stimulating brain cells to grow along with muscle cells.

Whether that translates to increased intelligence, better focus, or decreased anxiety is anybody's guess at this point.

For now, I'm putting my favorite form of exercise into the "might help, can't hurt" category. I'll continue lifting until I see evidence that it's making me stupid. And if it ever comes to that, I'll probably keep lifting anyway, since I'll be mentally impaired and incapable of changing my habits.  

Monday brain meat

• No surprises here: Parents report that seasonal allergies alter their kids' sleep, behavior, and academic performance. If you can't breathe and can't sleep, you can't learn.
• Also not a surprise: Kids have a lot of sex, but don't know enough about it to protect themselves from disease and unwanted pregnancies.