Spark

by John J. Ratey

To keep our brains at peak performance, our bodies need to work hard.

Why should you care about how your brain works? For one thing, it’s running the show. Right now the front of your brain is firing signals about what you’re reading, and how much of it you soak up has a lot to do with whether there is a proper balance of neurochemicals and growth factors to bind neurons together.

In addition to priming our state of mind, exercise influences learning directly, at the cellular level, improving the brain’s potential to log in and process new information.

What we now know is that the brain is flexible, or plastic in the parlance of neuroscientists—more Play-Doh than porcelain. It is an adaptable organ that can be molded by input in much the same way as a muscle can be sculpted by lifting barbells. The more you use it, the stronger and more flexible it becomes.

Cognitive flexibility is an important executive function that reflects our ability to shift thinking and to produce a steady flow of creative thoughts and answers as opposed to a regurgitation of the usual responses.

At the far end of the spectrum is what you know as being stressed out—a lonely place where issues that might ordinarily seem like challenges take on the proportions of insurmountable problems. Stay there too long, and we’re talking about chronic stress, which translates emotional strain into physical strain.

Chronic stress can even tear at the architecture of the brain.

“The mind is so powerful that we can set off the [stress] response just by imagining ourselves in a threatening situation,” writes Rockefeller University neuroscientist Bruce McEwen in his book The End of Stress as We Know It.

Just as the mind can affect the body, the body can affect the mind.

It’s stressful to be shunned or isolated. Loneliness is a threat to survival. Not coincidentally, the less physically active we are, the less likely we’ll be to reach out and touch someone.

Studies show that by adding physical activity to our lives, we become more socially active—it boosts our confidence and provides an opportunity to meet people. The vigor and motivation that exercise brings helps us establish and maintain social connections.

At every level, from the microcellular to the psychological, exercise not only wards off the ill effects of chronic stress; it can also reverse them.

The mechanisms by which exercise changes how we think and feel are so much more effective than donuts, medicines, and wine. When you say you feel less stressed out after you go for a swim, or even a fast walk, you are.

exercise is a prime example of acting out—dealing with our emotions physically rather than verbally.

Both stress and inactivity—the twin hallmarks of modern life—play big roles in the development of arthritis, chronic fatigue syndrome, fibromyalgia, and other autoimmune disorders. Reducing stress by any means, and especially exercise, helps patients with their recovery from these diseases.

Having normal levels of GABA is crucial to stopping, at the cellular level, the self-fulfilling prophecy of anxiety—it interrupts the obsessive feedback loop within the brain.

Our cognitive processors fail to tell us there is no problem or that it has passed and we can relax. There is so much noise in the mind from the sensory input of physical and mental tension that it clouds our ability to clearly assess the situation.

human beings are programmed to interpret facial expressions as survival cues).

There’s certainly nothing wrong with taking medicine, but if you can achieve the same results through exercise, you build confidence in your own ability to cope.

By doing something other than sitting and worrying, we reroute our thought process around the passive-response center and dilute the fear, while at the same time optimizing the brain to learn a new scenario.

High levels of the stress hormone cortisol kill neurons in the hippocampus. If you put a neuron in a petri dish and flood it with cortisol, its vital connections to other cells retract. Fewer synapses develop and the dendrites wither. This causes a communication breakdown, which, in the hippocampus of a depressed brain, could partly explain why it gets locked into thinking negative thoughts—it’s recycling a negative memory, perhaps because it can’t branch out to form alternative connections.

For the developing substance abuser, the overload of dopamine has tricked the brain into thinking that paying attention to the drug is a matter of life or death. “Drugs are tapping into the very core systems that have evolved to mediate survival,” says Robinson. “They activate the system in ways it was never meant to be activated.”

You can see how this nagging feeling—people describe it as a hollowness inside—could leave a person vulnerable to addictive behavior, from taking drugs to gorging on chocolate to playing video games forty hours a week.

Exercise fights the urge to smoke because in addition to smoothly increasing dopamine it also lowers anxiety, tension, and stress levels—the physical irritability that makes people so grouchy when they’re trying to quit.

The average woman has four hundred to five hundred menstrual cycles in her lifetime, each one lasting four to seven days. If you add them all up, it comes out to more than nine years—a long time for women who suffer premenstrual syndrome (PMS). “You can’t be bitchy and agitated and short-tempered and have a decent life,” says a thirty-eight-year-old colleague I’ll call Patty. “I know the feminists hate it when you say this, but some of us do go crazy.”

Isolation and inactivity feed the cellular death spiral, and this shrivels the brain.

It showed that people who feel lonely—those who identify with statements such as “I miss having people around” and “I experience a general sense of emptiness”—are twice as likely to develop Alzheimer’s.

The most consistent risk factor for cancer is lack of activity.

Today, of course, there’s no need to forage and hunt to survive. Yet our genes are coded for this activity, and our brains are meant to direct it. Take that activity away, and you’re disrupting a delicate biological balance that has been fine-tuned over half a million years.

From your genes to your emotions, your body and brain are dying to embrace the physical life. You are built to move. When you do, you’ll be on fire.