John J. Ratey, MD, is an Associate Clinical Professor of Psychiatry at Harvard Medical School and an internationally recognized expert in neuropsychiatry. He has published over sixty peer-reviewed articles and eleven books in seventeen languages. Recognized by his peers as one of the Best Doctors in America since 1997, he was recently honored by the Massachusetts Psychiatric Society as “Outstanding Psychiatrist of the Year” for advancing the field. His book Spark: The Revolutionary New Science of Exercise and the Brain established him as one of the world’s foremost authorities on the brain-fitness connection. In this interview, we discuss Spark and the effects of exercise on the brain.
Greg: Can you tell me a little bit about your background? How did you come to study the effects of exercise on the brain?
John: Well, it’s been lifelong. As an athlete all my life, I recognized how important it was for me to be active. When I got to medical school, we were just learning about antidepressants. There was an article in Medical News about a hospital in Sweden that offered depressed patients entering the hospital either an antidepressant or an exercise program, and their results were similar. So that turned me on to the link between exercise and the brain and I followed it all the way.
When I entered private practice, I had this miraculous patient who was a marathoner and a very productive professor. When he injured his knee and had to stop running, he came to see me because he had symptoms consistent with attention deficit disorder (ADD), which he had never had before.
He was a lifelong marathoner and had never stopped running. But with his knee injury, he stopped and got depressed. He got better but then developed typical symptoms of ADD. He couldn’t stay focused, he got angry, and so forth. So I became interested in the relationship between exercise and ADD and how exercise affected the brain and went on to write twelve books about it.
Then in 2000, there was a big story about the obesity crisis and this one amazing school district in Naperville, Illinois. Of the 19,000 kids in their school district, only 3% were overweight. And they didn’t have one obese child, mainly because of this incredible physical education (PE) program that was focused on fitness. Every day, they measured the students’ exercise and gave grades based on how much time they spent in their cardiac training zone. So it led everyone to be very, very fit, and that was great. Also, a few years before that, the whole school took an international science and math test, which students take every three years. 99% of the Naperville students participated, and they came in number one in the world in science and number six in math.
That got me on an airplane and led me to write Spark. I went into it really in depth and researched a thousand medical articles on exercise and the brain to write the book.
Greg: I grew up very close to Naperville. At the time, I believe Illinois was the only state in America that required PE every day for students. How exactly did Naperville run their program in comparison to other school districts in the state?
John: Naperville had revolutionized their PE program to focus on fitness first, which is a big deal because most PE programs had fitness somewhere like fifth or six in terms of their priorities. The other programs focused on learning skills and sports first.
But the Naperville program emphasized fitness first. The kids were measured. They started off by putting away the balls. All they did was fitness-based exercise for a while, but then they brought the balls back. They played three-on-three sports, kept it really small so everybody was playing all the time. Their whole focus was on getting kids moving and keeping them moving. And it paid off. They were an A++ school in Illinois, and they really competed with schools from the North Shore of Chicago for the highest number of National Merit Scholars and so forth.
I was out there every year for maybe five years and helped them develop some specific research programs with their students. They were known around the state and around the world. People used to visit them all the time. I’m not sure what’s going on now. I haven’t been in touch with them for a number of years, but yes, their program was very different.
Greg: You’ve touched on some of the positive effects of exercise on the brain, such as improving mood and learning. What are some additional benefits?
John: There are plenty of benefits. One big one is being focused and present in the moment. Exercise helps us regulate our emotional life, as well as make our brain the best it can be in terms of learning, taking in information, remembering, sorting, using our brain capacity to the maximum. It makes us the best learners as well as the most balanced, which helps our motivation. I talk all about this in Spark, about how various parts of our brain are stimulated.
There are so many studies showing that exercise improves what’s called our executive functions, which is how we remember, plan, predict, and evaluate consequences. And now we have studies showing that it makes us more creative. When we’re walking, we’re more creative than when we’re not. And this has led to a lot of walking meetings in the tech world.
And we change our brain chemistry almost immediately. Exercise increases all the neurotransmitters that we target in psychiatry for depression, anxiety and attention, as well as helping deal with cravings and addictions. It also makes us much more social, makes us much more eager to connect to other people.
The big thing that started off the whole revolution of looking at the effects of exercise on the brain was how exercise prevented the onset of cognitive decline and Alzheimer’s disease. That’s what drove the desire for more information in the 1990s and 2000s up until now. Researches wanted to know if exercise really does prevent our brain from atrophying or eroding and keeps our brain at a very high-pitch level.
Greg: It seems that exercise is almost a magic bullet when it comes to brain function. Are there any situations where researchers would expect exercise to have a benefit, but it turns out that there is none or perhaps the effects of exercise on the brain are harmful?
John: I haven’t ever seen anything about exercise being harmful to brain function. The hard part when doing a study in prisons or in schools, or even in the general population, is getting enough participants and the controls to really give you a double-blind placebo-controlled study. Think about doing a study in schools. You can look at the cases of schools that have bought into this approach all over the world. But the double-blind placebo-controlled studies, which are the signpost of something being scientific, are hard to do.
However, when we look at things like depression, anxiety, addiction, we can find studies that show, for instance, that exercise is as good as our antidepressants to treat people who are depressed and prevent people from getting depressed. They’ve done very careful studies all over the world, starting at Duke University Medical School and the University of Texas.
Greg: Are there specific types of exercise that are most beneficial for certain brain functions?
John: Well, everybody wants that. That’s everybody’s first and biggest question: “How much do I have to do?” Or, “How little do I have to do?” But it’s all about duration and intensity. The best exercise for people is something that they will come back to. It’s something that you enjoy, that you’ll come back to, that you do with somebody else, and that you usually do outside to get additional benefits.
Just raising your heart rate—which is the way we measure exercise in the U.S. more so than other countries—is great, and you’ll see improvement. But if you raise your heart rate and you also have balance and coordination challenges as well, like playing basketball or soccer, jumping rope, practicing dance or martial arts, you will get more bang for your buck than just running on a treadmill.
It’s all about staying with it and challenging your brain. The more you challenge your brain, the better the brain works.
Greg: Have you discovered anything in your research on exercise and brain function that surprised you?
John: One of the big surprises, which I put in Spark and was reconfirmed in recent studies looking at pregnant moms, was the benefits of exercise during pregnancy. Back in 2001, the OBGYN society said that when a mom gets pregnant, if she’s exercising, she should continue to exercise until it becomes unreasonable. They also said if a mom gets pregnant and is not exercising, she should begin. In addition to all the reasons why exercise helps everybody, exercise helps a pregnant mom a lot. The pregnancy is so much better tolerated, there’s less time spent on labor and delivery, and the babies come out thinner, more active, and eventually, they seem to have a higher IQ and are better fit for life.
Another one was the Stanford study showing that you’re more creative when you’re walking. You’re more creative than you were before walking, and the benefits continue even after you stop walking. But you’re most creative when you’re walking. And that was a big surprise for me and the researchers.
Greg: Going back to pregnancy, are there differences between men’s and women’s brains and between the effects of exercise on the brain in the two sexes?
John: Yes, there are differences, but they’re very slight. Usually, the woman’s left brain comes online and gets more functional early in life compared to men’s brains, but eventually, when you look at large numbers, it’s hard to see a difference.
I wrote a book called A User’s Guide to the Brain in 1999, which initially had a chapter on men’s and women’s brains, but we had to cut it because the book was too long. And there wasn’t a lot to say. There are differences, but not a huge amount.
But you always see some sex differences with exercise too. Both positive and negative. Some better for the men, some better for the women.
Greg: Can you touch on some of those differences in the effects of exercise on the brain between men and women?
John: I just reviewed a fairly big study today looking at exercise and its effect on income. They identified a group that exercised at least three times a week for six months and followed those people and looked at what they were earning. The women who exercised had a 10% increase in earning power compared to controls, and men only had a 6% increase in earning power compared to controls.
In Spark, I talk about the difference between men and women. Women get a bigger bang for their buck out of exercise, and not just the increased earnings. The effect on protecting the brain against cognitive decline and Alzheimer’s disease is greater in women because they are more prone to that as they enter menopause. Exercise helps prevent that cognitive decline. Also, women tend to get more depression than men, and exercise will help avoid that as well as treat it.