By John Ratey
My Personal Takeaways →Spark makes the neurological case for exercise: physical activity is not just good for your body, it is the single most powerful tool for optimizing brain function. Ratey draws on decades of research showing that exercise elevates mood, sharpens focus, combats anxiety and depression, and protects against cognitive decline — effects that no pill can replicate. The science is grounded in how movement promotes neuroplasticity, regulates stress hormones, and stimulates growth factors in the brain.
Read this if you need compelling evidence to make exercise non-negotiable. The practical takeaway is that frequency matters more than intensity: regular moderate aerobic exercise — even 20–30 minutes most days — produces measurable cognitive and emotional benefits. Implement it by treating exercise as a mental health tool, not only a physical one, and scheduling it before high-demand work or study sessions when possible.
By John J. Ratey and Eric Hagerman
The real reason we feel so good when we get our blood pumping is that it makes the brain function at its best, and in my view, this benefit of physical activity is far more important—and fascinating—than what it does for the body.
In Spark, I’ll demonstrate how and why physical activity is crucial to the way we think and feel. I’ll explain the science of how exercise cues the building blocks of learning in the brain; how it affects mood, anxiety, and attention; how it guards against stress and reverses some of the effects of aging in the brain; and how in women it can help stave off the sometimes tumultuous effects of hormonal changes.
They don’t know that toxic levels of stress erode the connections between the billions of nerve cells in the brain or that chronic depression shrinks certain areas of the brain. And they don’t know that, conversely, exercise unleashes a cascade of neurochemicals and growth factors that can reverse this process, physically bolstering the brain’s infrastructure.
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 order to cope with anxiousness, for instance, you need to let certain well-worn paths grow over while you blaze alternate trails.
If you had half an hour of exercise this morning, you’re in the right frame of mind to sit still and focus on this paragraph, and your brain is far more equipped to remember it.
My hope is that if you understand how physical activity improves brain function, you’ll be motivated to include it in your life in a positive way, rather than think of it as something you should do.
In October of 2000 researchers from Duke University made the New York Times with a study showing that exercise is better than sertraline (Zoloft) at treating depression. What great news! Unfortunately, it was buried on page fourteen of the Health and Fitness section. If exercise came in pill form, it would be plastered across the front page, hailed as the blockbuster drug of the century.
Exercise has a profound impact on cognitive abilities and mental health. It is simply one of the best treatments we have for most psychiatric problems.
And so are her Zero Hour classmates: at the end of the semester, they’ll show a 17 percent improvement in reading and comprehension, compared with a 10.7 percent improvement among the other literacy students who opted to sleep in and take standard phys ed. The administration is so impressed that it incorporates Zero Hour into the high school curriculum as a first-period literacy class called Learning Readiness PE. And the experiment continues. The literacy students are split into two classes: one second period, when they’re still feeling the effects of the exercise, and one eighth period. As expected, the second-period literacy class performs best.
“I tell people it’s not my job as a PE teacher to make kids fit,” Zientarski says. “My job is to make them know all of the things they need to know to keep themselves fit. Exercise in itself is not fun. It’s work. So if you can make them understand it, show them the benefits—that’s a radical transformation.
“One of the things that too many people forget is that you have to find something that allows a student to feel comfortable at excelling.”
What allows us to absorb the material is where the revolutionary new science comes into play. 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. Darwin taught us that learning is the survival mechanism we use to adapt to constantly changing environments. Inside the microenvironment of the brain, that means forging new connections between cells to relay information. When we learn something, whether it’s a French word or a salsa step, cells morph in order to encode that information; the memory physically becomes part of the brain.
What we now know is that the brain is flexible, or plastic in the parlance of neuroscientists—more Play-Doh than porcelain.
Likewise, our thoughts and behavior and environment reflect back on our neurons, influencing the pattern of connections. Far from being hardwired, as scientists once envisioned it, the brain is constantly being rewired. I’m here to teach you how to be your own electrician.
The way it works is that an electrical signal shoots down the axon, the outgoing branch, until it reaches the synapse, where a neurotransmitter carries the message across the synaptic gap in chemical form. On the other side, at the dendrite, or the receiving branch, the neurotransmitter plugs into a receptor—like a key into a lock—and this opens ion channels in the cell membrane to turn the signal back into electricity. If the electrical charge at the receiving neuron builds up beyond a certain threshold, that nerve cell fires a signal along its own axon, and the entire process repeats. About 80 percent of the signaling in the brain is carried out by two neurotransmitters that balance each other’s effect: glutamate stirs up activity to begin the signaling cascade, and gamma-aminobutyric acid (GABA) clamps down on activity. When glutamate delivers a signal between two neurons that haven’t spoken before, the activity primes the pump. The more often the connection is activated, the stronger the attraction becomes, which is what neuroscientists mean when they talk about binding. As the saying goes, neurons that fire together wire together. Which makes glutamate a crucial ingredient in learning.
I tell people that going for a run is like taking a little bit of Prozac and a little bit of Ritalin because, like the drugs, exercise elevates these neurotransmitters. It’s a handy metaphor to get the point across, but the deeper explanation is that exercise balances neurotransmitters—along with the rest of the neurochemicals in the brain. And as you’ll see, keeping your brain in balance can change your life.
As fundamental as the neurotransmitters are, there’s another class of master molecules that over the past fifteen years or so has dramatically changed our understanding of connections in the brain, specifically, how they develop and grow. I’m talking about a family of proteins loosely termed factors, the most prominent of which is brain-derived neurotrophic factor (BDNF). Whereas neurotransmitters carry out signaling, neurotrophins such as BDNF build and maintain the cell circuitry—the infrastructure itself.
About a dozen papers on BDNF were published before 1990, the year scientists discovered that it exists in the brain and nourishes neurons like fertilizer.
Say you’re learning a French word. The first time you hear it, nerve cells recruited for a new circuit fire a glutamate signal between each other. If you never practice the word again, the attraction between the synapses involved naturally diminishes, weakening the signal. You forget. The discovery that astonished memory researchers—and earned Columbia University neuroscientist Eric Kandel a share of the 2000 Nobel Prize—is that repeated activation, or practice, causes the synapses themselves to swell and make stronger connections. A neuron is like a tree that instead of leaves has synapses along its dendritic branches; eventually new branches sprout, providing more synapses to further solidify the connections. These changes are a form of cellular adaptation called synaptic plasticity, which is where BDNF takes center stage. Early on, researchers found that if they sprinkled BDNF onto neurons in a petri dish, the cells automatically sprouted new branches, producing the same structural growth required for learning—and causing me to think of BDNF as Miracle-Gro for the brain.
BDNF is a crucial biological link between thought, emotions, and movement.
Brain scans show that when we learn a new word, for example, the prefrontal cortex lights up with activity (as does the hippocampus and other pertinent areas, such as the auditory cortex). Once the circuit has been established by the firing of glutamate, and the word is learned, the prefrontal cortex goes dark. It has overseen the initial stages of the project, and now it can leave the responsibility to a team of capable employees while it moves on to new challenges. This is how we come to know things and how activities like riding a bike become second nature.
The news certainly came out of left field for me. For years, I had been a vocal proponent of using exercise for ADHD and many other psychological issues, based on what I’d seen with my own patients and what I knew about exercise’s effect on neurotransmitters. But this was different. By showing that exercise sparks the master molecule of the learning process, Cotman nailed down a direct biological connection between movement and cognitive function. In doing so, he blazed the trail for the study of exercise in neuroscience. Cotman conducted this experiment not long after BDNF was discovered in the brain, and there was nothing to suggest that exercise had anything to do with it; his hypothesis was an act of sheer creativity. He’d just finished working on a long-term aging study designed to see if the people whose minds hold up best share anything in common. Among those with the least cognitive decline over a four-year period, three factors turned up: education, self-efficacy, and exercise.
“One of the prominent features of exercise, which is sometimes not appreciated in studies, is an improvement in the rate of learning, and I think that’s a really cool take-home message,” Cotman says. “Because it suggests that if you’re in good shape, you may be able to learn and function more efficiently.” Indeed, in a 2007 study of humans, German researchers found that people learn vocabulary words 20 percent faster following exercise than they did before exercise, and that the rate of learning correlated directly with levels of BDNF. Along with that, people with a gene variation that robs them of BDNF are more likely to have learning deficiencies.
BDNF gives the synapses the tools they need to take in information, process it, associate it, remember it, and put it in context. Which isn’t to say that going for a run will turn you into a genius. “You can’t just inject BDNF and be smarter,” Cotman points out. “With learning, you have to respond to something in a different way. But the something has to be there.”
The branching caused by the environmental stimulation of learning, exercise, and social contact caused the synapses to form more connections, and those connections had thicker myelin sheaths, which allowed them to fire signals more efficiently.
What it means is that you have the power to change your brain. All you have to do is lace up your running shoes.
Gage went back to the environmental enrichment model to test this idea in rodents. “When we first did our experiments, we had all sorts of things going on,” Gage explains. “We needed to tease that out, and to our surprise, just putting a running wheel in a cage had a profound effect on the number of cells that were born. Ironically, with running, the same percentage of cells die as in the control group—it’s just that you have a bigger starting pool. But in order for a cell to survive and integrate, it has to fire its axon.” Exercise spawns neurons, and the stimulation of environmental enrichment helps those cells survive.
The body was designed to be pushed, and in pushing our bodies we push our brains too. Learning and memory evolved in concert with the motor functions that allowed our ancestors to track down food.
Now you know how exercise improves learning on three levels: first, it optimizes your mind-set to improve alertness, attention, and motivation; second, it prepares and encourages nerve cells to bind to one another, which is the cellular basis for logging in new information; and third, it spurs the development of new nerve cells from stem cells in the hippocampus.
One thing scientists know for sure is that you can’t learn difficult material while you’re exercising at high intensity because blood is shunted away from the prefrontal cortex, and this hampers your executive function. For example, while working out on the treadmill or the stationary bike for twenty minutes at a high intensity of 70 to 80 percent of their maximum heart rate, college students perform poorly on tests of complex learning. (So don’t study for the Law School Admission Test with the elliptical machine on full-tilt.) However, blood flow shifts back almost immediately after you finish exercising, and this is the perfect time to focus on a project that demands sharp thinking and complex analysis.
So if you have an important afternoon brainstorming session scheduled, going for a short, intense run during lunchtime is a smart idea.
As for how much aerobic exercise you need to stay sharp, one small but scientifically sound study from Japan found that jogging thirty minutes just two or three times a week for twelve weeks improved executive function. But it’s important to mix in some form of activity that demands coordination beyond putting one foot in front of the other. Greenough worked on an experiment several years ago in which running rats were compared to others that were taught complex motor skills, such as walking across balance beams, unstable objects, and elastic rope ladders. After two weeks of training, the acrobatic rats had a 35 percent increase of BDNF in the cerebellum, whereas the running rats had none in that area. This extends what we know from the neurogenesis research: that aerobic exercise and complex activity have different beneficial effects on the brain.
What I would suggest, then, is to either choose a sport that simultaneously taxes the cardiovascular system and the brain—tennis is a good example—or do a ten-minute aerobic warm-up before something nonaerobic and skill-based, such as rock climbing or balance drills.
The same would hold true for learning tango. The fact that you have to react to another person puts further demands on your attention, judgment, and precision of movement, exponentially increasing the complexity of the situation. Add in the fun and social aspect, and you’re activating the brain and the muscles all the way down through the system.
Neurons get broken down and built up just like muscles—stressing them makes them more resilient. This is how exercise forces the body and mind to adapt.
If we strip away everything else, our ingrained reaction to stress is about focusing on the danger, fueling the reaction, and logging in the experience for future reference, which I think of as wisdom. It is only in recent years that scientists have begun to recognize and describe the role of stress in the formation and recall of memories. The development of this understanding is exciting because it sheds light on why—(and how)—stress can have such a profound effect on the way we perceive the world. The fight-or-flight response calls into action several of the body’s most powerful hormones and scores of neurochemicals in the brain. The brain’s panic button, called the amygdala, sets off the chain reaction on receiving sensory input about a possible threat to the body’s natural equilibrium. Being hunted would certainly qualify, but so would being the hunter. The amygdala’s job is to assign intensity to the incoming information, which may or may not be obviously survival related. It’s not just about fear, but any intense emotional state, including, for example, euphoria or sexual arousal. Winning the lottery or dining with a supermodel can trigger the amygdala. These events may not seem stressful, but remember, our brains don’t distinguish between “good” and “bad” demands on the system. And in an evolutionary light, good fortune and a good date are related to survival—prospering and procreating.
Two neurotransmitters put the brain on alert: norepinephrine arouses attention, then dopamine sharpens and focuses it. An imbalance of these neurotransmitters is why some people with attention-deficit/hyperactivity disorder (ADHD) come across as stress junkies. They have to get stressed to focus. It’s one of the primary factors in procrastination. People learn to wait until the Sword of Damocles is ready to fall—it’s only then, when stress unleashes norepinephrine and dopamine, that they can sit down and do the work. A need for stress also explains why ADHD patients sometimes seem to shoot themselves in the foot. When everything is going well, they need to stir up the situation, and they subconsciously find a way to create a crisis.
Cortisol takes over for epinephrine and signals the liver to make more glucose available in the bloodstream, while at the same time blocking insulin receptors at nonessential tissues and organs and shutting down certain intersections so the fuel flows only to areas important to fight-or-flight. The strategy is to make the body insulin-resistant so the brain has enough glucose. Cortisol also begins restocking the shelves, so to speak, replenishing energy stores depleted by the action of epinephrine. It converts protein into glycogen and begins the process of storing fat. If this process continues unabated, as in chronic stress, the action of cortisol amasses a surplus fuel supply around the abdomen in the form of belly fat. (Unrelenting cortisol also explains why some marathon runners carry a slight paunch despite all their training—their bodies never get a chance to adequately recover.)
Operating on a fixed budget of fuel, the brain has evolved to shift energy resources as necessary, meaning that mental processing is competitive. It’s simply not possible to have all of our neurons firing at once, so if one structure is active, it must come at the expense of another. One of the problems with chronic stress is that if the HPA axis is guzzling all the fuel to keep the system on alert, the thinking parts of the brain are being robbed of energy.
The beefed-up cells cement the survival memory and shield the neurons in that circuit from other demands. A neuron might be part of any number of memories. But if a potential memory comes along during stress, it has a more difficult time recruiting neurons to be part of its own new circuit. It needs to clear a certain threshold to make an impression. This likely explains why memories not related to the stressor are blocked during the stress response. It also helps explain why constantly high levels of cortisol—due to chronic stress—make it hard to learn new material, and why people who are depressed have trouble learning. It’s not just lack of motivation, it’s because the hippocampal neurons have bolstered their glutamate machinery and shut out less important stimuli. They’re obsessed with the stress. Human studies also show that excess cortisol can block access to existing memories, which explains how people can forget where the fire exit is when there’s actually a fire—the lines are down, so to speak. With too much stress, we lose the ability to form unrelated memories, and we might not be able to retrieve the ones we have. The next time you’re forced to participate in a fire drill, consider that the neurological point of the exercise is to make those circuits stronger, to burn in the memory.
The stress response is elegantly adaptive behavior, but because it doesn’t get you very far in today’s world, there’s no outlet for all that energy buildup. You have to make a conscious effort to initiate the physical component of fight or flight.
In the context of stress, the great paradox of the modern age may be that there is not more hardship, just more news—and too much of it. The 24/7 streaming torrent of tragedy and demands flashing at us from an array of digital displays keeps the amygdala flying. The negative and the hectic and the hopeless heap on the stress, but we figure we can handle it because we always have. Up to a point. Then, we just want to relax and take a break, so we grab a drink and plop down in front of the TV or go sit on a beach somewhere. It’s no wonder that obesity has doubled in the past twenty years—our lifestyle today is both more stressful and more sedentary.
Metabolic stress happens when the cells can’t produce adequate ATP, either because glucose can’t get into the cell or because there’s not enough of it to go around. Excitotoxic stress occurs when there is so much glutamate activity that there isn’t enough ATP to keep up with the energy demand of the increased information flow. If this continues for too long without recovery, there’s a problem. The cell is on a death march—forced to work without food or resources to repair the damage. The dendrites begin to shrink back and eventually cause the cell to die. This is neurodegeneration, the mechanism underlying diseases such as Alzheimer’s, Parkinson’s, and even aging itself. It’s largely through intensive study of these diseases that scientists have discovered the body’s natural countermeasures to cellular stress. And this explains why Mark Mattson, who is chief of the neurosciences lab at the National Institute on Aging, is so stingy with the food for his lab rats. In many of his experiments, Mattson uses dietary restriction to cause mild cellular stress—there isn’t enough glucose to produce adequate amounts of ATP—and he’s found that mice and rats that are given a third of their normal calories live up to 40 percent longer than average. His work has helped identify protective molecules unleashed during various types of stress, including aerobic exercise.
The advantage of using exercise to inoculate the brain against stress is that it ramps up growth factors more than other stimuli do.
The best way to build them up is by bringing mild stress on yourself: using the brain to learn, restricting calories, exercising, and, as Mattson and your mother would remind you, eating your vegetables.
Sometimes the fight-or-flight switch gets stuck in the on position. It can be a function of genetics, according to epidemiological surveys: if you put a random group of people in a stressful public speaking situation, those whose parents suffered from hypertension still show elevated levels of cortisol twenty-four hours after the speech. Or it can be environmental: prenatal rats whose mothers are subjected to repeated stress grow up to have a lower stress threshold than their normal counterparts. Which is to say they get stressed out more easily, both physically and psychologically.
It’s what happens after exercise that optimizes the brain. In addition to raising the fight-or-flight threshold, it kick-starts the cellular recovery process I have described. Exercise increases the efficiency of intercellular energy production, allowing neurons to meet fuel demands without increasing toxic oxidative stress. We do get waste buildup, but we also get the enzymes that chew it up, not to mention a janitorial service that disposes of broken bits of DNA and other by-products of normal cellular use and aging—both of which are thought to help prevent the onset of cancer and neurodegeneration. And while exercise induces the stress response, if the activity level isn’t extreme, it shouldn’t flood the system with cortisol.
The stress of exercise is predictable and controllable because you’re initiating the action, and these two variables are key to psychology. With exercise, you gain a sense of mastery and self-confidence. As you develop awareness of your own ability to manage stress and not rely on negative coping mechanisms, you increase your ability to “snap out of it,” so to speak. You learn to trust that you can deal with it.
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.
Chronic stress is linked to some of our most deadly diseases. If repeated spikes in blood pressure damage the vessels, plaque can build up at those areas and lead to atherosclerosis. As I mentioned earlier, an unchecked stress response can stockpile fat around the midsection, which studies have shown to be more dangerous than fat stored elsewhere.
In 2004 researchers at Leeds Metropolitan University in England found that workers who used their company’s gym were more productive and felt better able to handle their workloads. Most of the 210 participants in the study took an aerobics class at lunchtime, for forty-five minutes to an hour, but others lifted weights or practiced yoga for thirty minutes to an hour. They filled out questionnaires at the end of every workday about how well they interacted with colleagues, managed their time, and met deadlines. Some 65 percent fared better in all three categories on days they exercised. Overall, they felt better about their work and less stressed when they exercised. And they felt less fatigued in the afternoon, despite expending energy at lunchtime.
In recent years, doctors have started recommending exercise for cancer patients, both to help boost the immune response and to fend off stress and depression. Nobody says exercise cures cancer, but research suggests that activity is clearly a factor in some forms of the disease: twenty-three of thirty-five studies show an increased risk of breast cancer for those women who are inactive; physically active people have 50 percent less chance of developing colon cancer; and active men over sixty-five have a 70 percent lower chance of developing the advanced, typically fatal form of prostate cancer. It all comes back to the evolutionary paradox that even though it’s much easier to survive in the modern world, we experience more stress. The fact that we’re much less active than our ancestors were only exacerbates matters. Just keep in mind that the more stress you have, the more your body needs to move to keep your brain running smoothly.
When you’re facing an upcoming speech or a brewing confrontation with your boss, anxiety sharpens your attention so you can meet the challenge. The physical symptoms range from feeling tense, jittery, and short of breath to experiencing a racing heart, sweating, and, in the case of full-blown panic attacks, severe chest pains. Emotionally, what you feel is fear.
Over time, you teach the brain that the symptoms don’t always spell doom and that you can survive; you’re reprogramming the cognitive misinterpretation.
Moving the body also triggers the release of gammaamino-butyric acid (GABA), which is the brain’s major inhibitory neurotransmitter (and the primary target for most of our antianxiety medicines).
As for the trait, the majority of studies show that aerobic exercise significantly alleviates symptoms of any anxiety disorder. But exercise also helps the average person reduce normal feelings of anxiousness.
Anxiety is fear, but what is fear? In neurological terms, fear is the memory of danger. If we suffer from an anxiety disorder, the brain constantly replays that memory, forcing us to live in that fear. It all starts when the amygdala sounds the survival call, but unlike the normal stress response, in anxiety the all-clear signal isn’t working properly. Our cognitive processors fail to tell us there is no problem or that it has passed and we can relax.
One of the correlations scientists have found among people with generalized anxiety disorder is brain scans that show the area of the prefrontal cortex responsible for sending cease-and-desist signals to the amygdala as being smaller than it should be. Left unchecked, the overexcited amygdala tags too many situations as challenges to survival and burns them into memory. The fear memories form connections with each other, and the anxiety snowballs. Eventually, the amygdala overwhelms attempts by the hippocampus to tone down the fight-or-flight response by putting the fear in context. As the snowball grows and more and more memories become associated with fear, your world shrinks.
A huge part of the problem with social anxiety, whether it’s at the level of Ellen’s phobia or milder social apprehension, is that the more we withdraw, the less practice we get interacting, and the scarier the prospect becomes.
Just as anxiety can feed on itself, so can courage.
Because the rapid, shallow breathing expels too much carbon dioxide, the blood’s pH level drops, triggering an alarm from the brain stem that causes muscles to constrict even more. (This is why breathing into a paper bag stops us from hyperventilating: it forces us to rebreathe the carbon dioxide.)
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. This is a significant advantage not just for patients with full-blown anxiety disorders, but for anyone. We all face situations in everyday life that cause fear and anxiousness. The trick, as my patient Amy illustrates, is in how you respond.
While we can’t erase the original fear memory, we can essentially drown it out by creating a new memory and reinforcing it. By building up parallel circuitry to the fear memory, the brain creates a neutral alternative to the expected anxiety, learning that everything is OK. By wiring in the correct interpretation, the trigger is disconnected from the typical response, weakening the association between, say, seeing a spider and experiencing terror and a racing heart. Scientists call it reattribution. We can force the brain to trade fear memories for neutral or positive ones through a form of psychology called cognitive behavioral therapy (CBT).
Everyone’s initial instinct in the face of anxiety is to avoid the situation, like a rat that freezes in its cage. But doing just the opposite, we engage in cognitive restructuring, using our bodies to cure our brains.
The elegance of exercise as a way to deal with anxiety, in everyday life and in the form of a disorder, is that it works on both the body and the brain. Here’s how: 1. It provides distraction. Quite literally, moving puts your mind on something else, just as using the elliptical trainer helped my patient Amy break out of her acute state of anxiety and focus on something other than the fear of her next panic attack. Studies have shown that anxious people respond well to any directed distraction—quietly sitting, meditating, eating lunch with a group, reading a magazine. But the antianxiety effects of exercise last longer and carry the other side benefits listed here. 2. It reduces muscle tension. Exercise serves as a circuit breaker just like beta-blockers, interrupting the negative feedback loop from the body to the brain that heightens anxiety. Back in 1982 a researcher named Herbert de Vries conducted a study showing that people with anxiety have overactive electrical patterns in their muscle spindles and that exercise reduced that tension (just as beta-blockers do). He called it the “tranquilizing effects of exercise.” Reducing muscle tension, he found, reduced the feeling of anxiety, which, as I’ve explained, is important to extinguishing not just the state but the trait of anxiety. 3. It builds brain resources. You know by now that exercise increases serotonin and norepinephrine both in the moment and over the long term. Serotonin works at nearly every junction of the anxiety circuitry, regulating signals at the brain stem, improving the performance of the prefrontal cortex to inhibit the fear, and calming down the amygdala itself. Norepinephrine is the arousal neurotransmitter, so modulating its activity is critical to breaking the anxiety cycle. Physical activity also increases the inhibitory neurotransmitter GABA as well as BDNF, which is important for cementing alternative memories. 4. It teaches a different outcome. One aspect of anxiety that makes it so different from other disorders is the physical symptoms. Because anxiety brings the sympathetic nervous system into play, when you sense your heart rate and breathing picking up, that awareness can trigger anxiety or a panic attack. But those same symptoms are inherent to aerobic exercise—and that’s a good thing. If you begin to associate the physical symptoms of anxiety with something positive, something that you initiated and can control, the fear memory fades in contrast to the fresh one taking shape. Think of it as a biological bait and switch—your mind is expecting a panic attack, but instead it ends up with a positive association with the symptoms. 5. It reroutes your circuits. By activating the sympathetic nervous system through exercise, you break free from the trap of passively waiting and worrying, and thus prevent the amygdala from running wild and reinforcing the danger-filled view of what life is presenting. Instead, when you respond with action, you send information down a different pathway of the amygdala, paving a safe detour and wearing in a good groove. You’re improving alternate connections, actively learning an alternative reality. 6. It improves resilience. You learn that you can be effective in controlling anxiety without letting it turn into panic. The psychological term is self-mastery, and developing it is a powerful prophylactic against anxiety sensitivity and against depression, which can develop from anxiety. In consciously making the decision to do something for yourself, you begin to realize that you can of that, and the treatment, is taking action, do something for yourself. It’s a very tautology. 7. It sets you free. Researchers immobilize rats in order to study stress. In people too, if you’re locked down-literally or figuratively -you’ll feel more anxious. People who are anxious tend to immobilize themselves- balling up in a fetal position or just finding a safe spot to hide from the world. Agoraphobics feel trapped in their homes, but in a sense any form of anxiety feels like a trap. The opposite of that, and the treatment, is taking action, going out and exploring, moving through the environment.
First of all, he’s deeply phobic about a panic attack coming on. And because panic disorder is so frightening, I usually start with medicine. Taking a pill doesn’t require a lot of effort, and in some cases it works like flipping a switch to diffuse the trigger. But, as I mentioned, it doesn’t necessarily lead to a permanent change, and the relearning process needs to happen for long-term relief. Why not come out with both guns blazing? I think combining medicine with exercise can be a great approach. Medicine provides immediate safety, and exercise gets at the fundamentals of anxiety.
One long-term study followed seven hundred children into adulthood. Of those who suffered from anxiety as children, most grew out of it. But of those who developed a mood disorder, in two-thirds of the cases the problem started as preadolescent anxiety. What’s tragic here is that anxiety is relatively easy to treat, but it often goes undiagnosed in children—the anxious kids are sitting quietly at the back of the class, terrified. Nobody notices there is something wrong because these kids are well behaved. Meanwhile, the anxiety is wearing in negative patterns in their brains that can become entrenched and set these kids up for future problems. I told the young man that the A-number-one thing he needed to do was exercise with somebody. That goes for anyone who is panicky. It offers a sense of safety, but it also increases levels of serotonin immediately, just from being around another person.
A lot of people who are treated for panic disorder can go on to have a completely different kind of life. The farther they get from their last panic episode, the less likely they are to have another panic episode. The same holds true for any brand and any degree of anxiety. The more your life changes, the more you engage with the world, the more likely you are to put the anxiety behind you for good.
Overall, I think of depression as an erosion of connections—in your life as well as between your brain cells.
Endorphins, as they became known, dulled pain in the body and produced euphoria in the mind. When elevated levels of endorphins were detected in the blood samples of a group of runners, everything seemed to fit. The theory that exercise fills your brain with this morphinelike substance matched the good feeling everyone got. It gave us the expression “runner’s high,” an extreme version of the effect.
We’ve known for a while that exercise influences the same chemicals as antidepressants do, but nobody had done a scientifically sound head-to-head comparison until researchers at Duke University took up the task in 1999. In a landmark study affectionately called SMILE (Standard Medical Intervention and Long-term Exercise), James Blumenthal and his colleagues pitted exercise against the SSRI sertraline (Zoloft) in a sixteen-week trial. They randomly divided 156 patients into three groups: Zoloft, exercise, or a combination of the two. The exercise group was assigned to supervised walking or jogging, at 70 to 85 percent of their aerobic capacity, for thirty minutes (not including a ten-minute warm-up and a five-minute cool-down) three times a week. The results? All three groups showed a significant drop in depression, and about half of each group was completely out of the woods—in remission. Another 13 percent experienced fewer symptoms but didn’t fully recover. Blumenthal concluded that exercise was as effective as medication.
If everyone knew that exercise worked as well as Zoloft, I think we could put a real dent in the disease.
Madhukar Trivedi, a clinical psychiatrist who is the director of the Mood Disorders Research Program at the University of Texas Southwestern Medical School, has been researching the effectiveness of using exercise to augment antidepressants. In 2006 he published a pilot study showing that patients who weren’t responding to antidepressants lowered their scores on a common depression test by 10.4 points on a 17-point scale—a huge drop—after twelve weeks of exercise.
We knew the amygdala was central to our emotional life, but we were just discovering that the memory center was also involved in stress and depression. In 1996 Yvette Sheline of Washington University in St. Louis compared ten patients with depression to ten healthy controls of the same physical stature and educational background, and she found that the hippocampus of depressed patients was up to 15 percent smaller compared to that of the controls. She also found evidence that the degree of shrinkage was directly related to the length of depression, and this was news. It might explain why so many patients with depression complain of learning and memory trouble, and why mood deteriorates in Alzheimer’s, the neurodegenerative disease that begins with erosion of the hippocampus. 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.
Redefining depression as a connectivity issue helps explain the wide range of symptoms people experience. It’s not just a matter of feeling empty, helpless, and hopeless. It affects learning, attention, energy, and motivation—disparate systems that involve different parts of the thinking brain. Depression also affects the body, shutting down the drive to sleep, eat, have sex, and generally look after ourselves on a primitive level. Psychiatrist Alexander Niculescu sees depression as a survival instinct to conserve resources in an environment void of hope—”to keep still and stay out of harm’s way,” he wrote in a 2005 article in Genome Biology. It’s a form of hibernation: When the emotional landscape turns wintry, our neurobiology tells us to stay inside. Except that it can last much longer than a season.
Conversely, scientists have bred mice with genes that produce 50 percent less BDNF and found that they don’t respond well to antidepressants, suggesting it’s a necessary ingredient for the drugs to work. Such mice were significantly slower to try to escape stress than their peers with normal BDNF function.
Exercise boosts BDNF at least as much as antidepressants, and sometimes more, in the rat hippocampus. One study showed that combining exercise with antidepressants spiked BDNF by 250 percent. And in humans, we know that exercise raises BDNF, at least in the bloodstream, much like antidepressants do.
What makes aerobic exercise so powerful is that it’s our evolutionary method of generating that spark. It lights a fire on every level of your brain, from stoking up the neurons’ metabolic furnaces to forging the very structures that transmit information from one synapse to the next.
“Part of the initial rehab is simply to get them doing something. The best kind of behavioral therapy is to just go outside, go for a walk. Do something. It doesn’t require you to have elaborate planning. It doesn’t put you into a negative spin. If you do a physical activity, it’s very quickly reinforcing because, before, you couldn’t initiate to make yourself do something.” If your prefrontal cortex has been offline for a while, you need to reprogram it, and exercise is the perfect tool. You begin to look at the world differently, and you see trees instead of a barren wasteland. When you see yourself moving, that alone is an achievement—proof that you can help yourself.
Human beings are social animals, so if you’re depressed, it would be ideal to choose a form of exercise that encourages making connections and that can take place outside or in some environment that stimulates the senses. Asking someone to join you in exercise and putting yourself in a new setting will give those newly hatched neurons a powerful reason for being; new connections need to be formed to represent the sensory stimulation.
The first question people ask me when I suggest exercise as therapy is “How much should I do?” There is no firm answer—especially given depression’s wide spectrum of symptoms and severity—but Madhukar Trivedi has drawn some conclusions about the amount necessary to be effective. By quantifying exercise as a dose, he hopes to cast treatment in terms the medical profession might accept. This is all-important, because doctors have to spend time with their patients to figure out what sort of regimen is likely to keep them moving. In one study, Trivedi and Andrea Dunn divided eighty depressed patients into five groups, four with exercise protocols of different intensities and frequencies and one control group assigned to supervised stretching only (to see if social interaction with the supervisors had any effect). They used calories burned per pound of body weight as the “dose” measure. The high-intensity groups burned an average of 1,400 calories (eight calories per pound) during the course of either three or five sessions per week. At the end of three months, regardless of frequency, the high-intensity groups cut their depression scores in half. Practically speaking, their symptoms dropped significantly. The low-intensity groups burned an average of 560 calories (three calories per pound) and lowered their scores by a third, about the same as the stretching group—and about as effective as a placebo. What this means for us is what I always tell people: some exercise is good, more is better (to a point). Trivedi and Dunn based the high dose on public health recommendations for exercise, which suggest thirty minutes of moderate aerobic activity on most days. If you weigh 150 pounds, that would translate into about three hours at moderate intensity per week. The low dose would be equivalent to eighty minutes per week.
And giving bipolar patients a stable social routine has been shown to improve long-term outcomes. It’s only been very recently that exercise started making its way into treatment protocols for bipolar disorder.
In some ways, exercise is even more important for prevention than it is for treatment. One of the first symptoms of depression, even before your mood drops to new lows, is sleep disturbance. Either you can’t get up or you can’t get to sleep or both. I think of it as sleep inertia—trouble starting or stopping. First you lose your energy, then your interest in things. The key is to get moving immediately. And do not stop. Set up a schedule for a daily walk, run, jog, bike ride, or dance class. If you can’t sleep, go for a walk in the dawn light and do it every day. Take the dog out, change your schedule—run from the depression. Burn those 1,400 calories as if your life depended on it, and nip it in the bud.
First, see your doctor about medication and get yourself some omega-3 supplements, which are proven to have antidepressant effects. This will, I hope, loosen up the brain lock enough for you to at least go for a walk. Ask for help. Get a friend or family member to agree to come by every day, at the same time if possible, to escort you outside and around the block.
If that’s not an option, and you have the means, set up a regular time with a personal trainer. This might sound crazy, I realize, if you feel like you can’t even lift yourself off the couch, but if that’s the case, activity is all the more urgent.
It’s a process, and the best strategy is to take it one step—and then one stride—at a time. Start slowly and build on it. At its core, depression is defined by an absence of moving toward anything, and exercise is the way to divert those negative signals and trick the brain into coming out of hibernation.
While it’s true that people with ADHD “just need to get motivated,” it’s also true that, like every other aspect of our psychology, motivation is biological. What about the child who can’t pay attention in class but can sit perfectly still for hours playing a video game? Or the woman who “spaces out” when her husband is talking but has no trouble focusing on magazine gossip about Brad and Angelina? Obviously, they can pay attention when they want to, right? Not exactly. If we were to look at functional MRI (fMRI) scans of the brains of these people—and scientists have—we would see distinct differences in activity at the reward center in each situation. The reward center is a cluster of dopamine neurons called the nucleus accumbens, which is responsible for doling out pleasure or satisfaction signals to the prefrontal cortex, and thus providing the necessary drive or motivation to focus. The sort of stimulation that will activate the reward center enough to capture the brain’s attention varies from person to person.
Paradoxically, the ability to hyperfocus is a common trait of ADHD, and it often leads people to miss the diagnosis because it doesn’t seem to fit. New patients will tell me that they can’t possibly have ADHD since they often get completely absorbed in what they’re reading or doing. But the glitch in the attention system isn’t strictly a deficit—it’s more of an inability to direct attention or to focus on command. I tell my patients a more helpful way to think of ADHD is as an attention variability disorder; the deficit is one of consistency.
It’s easy to get distracted in today’s world. It’s become so full of information, noise, and interruptions that all of us feel overwhelmed and unfocused at times. The amount of data in the world is doubling every few years, but our attention system, like the rest of the brain, was built to make sense of the surrounding environment as it existed ten thousand years ago.
Experts estimate that just over 4 percent of American adults—that’s thirteen million people—have ADHD, which is not to say that the remaining 96 percent of the population is completely free of attention problems. To a certain degree, everyone suffers from fleeting attention. And as I’ve mentioned, there are varying degrees of severity for many mental health disorders—shadow syndromes, which are personality traits that don’t necessarily meet the full checklist of symptoms doctors rely on to make diagnoses.
Over the years, I’ve heard countless parents offer the same observation about their ADHD children: Johnny is so much better when he’s doing tae kwon do. He wasn’t doing his homework, and he was angry, difficult, and problematic; now his best qualities have come out. You could substitute any of the martial arts here or any highly structured form of exercise such as ballet, figure skating, or gymnastics. Less traditional sports, such as rock climbing, mountain biking, whitewater paddling, and—sorry to tell you, Mom—skateboarding, are also effective in the sense that they require complex movements in the midst of heavy exertion. The combination of challenging the brain and the body has a greater positive impact than aerobic exercise alone. One small study from a graduate student at Hofstra University tested this fact. He found that ADHD boys age eight to eleven participating in martial arts twice a week improved their behavior and performance on a number of measures compared to those on a typical aerobic exercise program (both kinds of exercise led to dramatic improvement over nonactive controls).
Turns out that there’s a lot of overlap between attention, consciousness, and movement. The attention circuits are jointly regulated by the neurotransmitters norepinephrine and dopamine, which are so similar on a molecular level that they can plug into each others’ receptors. These are the chemicals targeted by ADHD medications.
The reward center needs to be sufficiently activated before it will carry out its important duty of telling the prefrontal cortex that something is worth paying attention to. It engages the prioritizing aspect of executive function, and this is a central component of motivation. Essentially, the brain won’t do much unless the reward center is responsive. Laboratory studies have shown that monkeys with lesions in the nucleus accumbens cannot sustain attention and thus can’t muster the motivation to perform tasks that don’t carry immediate rewards. The same is true of people with ADHD, who favor immediate gratification over more mundane tasks that will help them down the road, like studying for a test that will help them get into college. I call them prisoners of the present. They can’t maintain focus on a long-term goal, and so it seems as though they lack drive.
A failure of working memory is also why people with ADHD are terrible at keeping track of time and thus prone to procrastination. They literally forget to worry about the passing time, so they never get started on the task at hand.
This is where the attention system ties in with movement and thus exercise: the areas of the brain that control physical movement also coordinate the flow of information. The cerebellum is a primitive part of the brain that for decades was assumed to be involved only with governing and refining movement. When we learn how to do something physical, whether it’s a karate kick or snapping our fingers, the cerebellum is hard at work. The cerebellum takes up just 10 percent of the brain’s volume, but it contains half of our neurons, which means it’s a densely packed area constantly buzzing with activity. But it keeps rhythm for more than just motor movements: it regulates certain brain systems so they run smoothly, updating and managing the flow of information to keep it moving seamlessly.
Dopamine works like transmission fluid: if there’s not enough, as is the case in people with ADHD, attention can’t easily be shifted or can only be shifted all the way into high gear.
The parallel is important because, based on a number of strong studies, neurologists are now recommending daily exercise in the early stages of Parkinson’s disease to stave off symptoms. Scientists induced Parkinson’s in rats by killing the dopamine cells in their basal ganglia, and then forced half of them to run on a treadmill twice a day in the ten days following the “onset” of the disease. Incredibly, the runners’ dopamine levels stayed within normal ranges and their motor skills didn’t deteriorate. In one study on people with Parkinson’s, intensive activity improved motor ability as well as mood, and the positive effects lasted for at least six weeks after they stopped exercising.
A controversial treatment for dyslexia—which occurs in about 30 percent of ADHD patients—relies entirely on physical movements to train the cerebellum. Dyslexia, dyspraxia, and attention treatment (DDAT) is based on the theory that a disruption in the brain’s ability to coordinate movement might be responsible for eye-tracking problems and thus difficulties in learning to read and write. Researchers also know that most children with dyslexia perform worse than average on tests of cerebellar function. DDAT involves practicing a collection of fairly simple motor-skills drills twice a day for ten minutes. In 2003 British researchers tested the effectiveness of DDAT on thirty-five children with dyslexia and declared the results “astounding.” Compared to no treatment, the students who followed the DDAT regimen for six months showed a significant improvement in reading and writing fluency, eye movement, cognitive skills, and physical measures such as dexterity and balance.
Within a large population of prisoners, he discovered that more than 80 percent of them had had serious learning problems as children.
With regular exercise, we can raise the baseline levels of dopamine and norepinephrine by spurring the growth of new receptors in certain brain areas.
Exercise increases dopamine levels in the rat equivalent of this area by creating new dopamine receptors.
Exercise also increases norepinephrine. And the more complex the exercise, the better. Rats don’t do judo, but scientists have looked at the neurochemical changes in their brains after periods of acrobatic exercise, the closest parallel to martial arts. Compared to rats running on a treadmill, their cohorts who practiced complex motor skills improved levels of brain-derived neurotrophic factor (BDNF) more dramatically, which suggests that growth is happening in the cerebellum
The best strategy is to exercise in the morning, and then take the medication about an hour later, which is generally when the immediate focusing effects of exercise begin to wear off. For a number of patients, I find that if they exercise daily, they need a lower dose of stimulant.
I tell my patients they need to develop militant vigilance in terms of scheduling and structure. If you set up your environment in a certain way, you can corral your attention through your own actions and become more productive. Arrange your day and your surroundings in a way that encourages focus and accomplishment.
Scientists are now characterizing behavior such as gambling, compulsive shopping, and even overeating in the same biological terms they use to explain substance abuse. The common denominator is an out-of-control reward system, which some people are born with and some people develop.
As an antidote, you’re giving the individual an avenue of life experience that most have not had—the goals of exercise, the feeling of exercise, the challenge of exercise, the pleasure and the pain, the accomplishment, the physical well-being, the self-esteem. All that exercise gives us, you’re now presenting to the addict as a very compelling option.
Indeed, by studying how dopamine works as the key messenger in the reward system, scientists have drawn a distinction between liking something and wanting it. “Liking refers to the actual experience of pleasure, versus the motivational state, which is the willingness to work for rewards,” says Terry Robinson, a behavioral neuroscientist at the University of Michigan. “Dopamine is involved in this wanting, but it’s not involved in liking.”
Typically, when we learn something, the connections stabilize and the levels of dopamine tail off over time. With addiction, especially drug addiction, dopamine floods the system with each drug use, reinforcing the memory and pushing other stimuli further into the background. Animal studies show that drugs such as cocaine and amphetamine make the dendrites in the nucleus accumbens bloom, thus increasing their synaptic connections. The changes can remain months and maybe even years after the drugs are stopped, which is why it’s so easy to relapse.
And in recent years, imaging studies have shown that the prefrontal cortex doesn’t fully develop until we are well into our twenties, which could explain why most people who experiment with drugs and get hooked do so as teenagers or during early adulthood, when their inhibition hasn’t fully developed. “They end up with a hypersensitive system that wants drugs, and they make very bad decisions,” says Robinson.
Exercise was a conduit for shifting Rusty’s focus to a more productive life. I see exercise as a way of offsetting the feeling of hopelessness and uselessness that a lot of drug users have, and that certainly was a factor with Rusty. The routine and the physical activity gets the brain engaged and the mind moving in a direction other than toward the drug, reprogramming the basal ganglia to wire in an alternative reflexive behavior.
If you continually subject your brain to an overload of dopamine, the number of receptors will dwindle. So regardless of what your brain looked like when you were born, the more drugs you take, the more drugs you’ll need to feel the same rush. The same is true of people of people who overeat: “You need more, more, more to make you feel good,”
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. Exercise can fend off cravings for fifty minutes and double or triple the interval to the next cigarette. And the fact that exercise sharpens thinking comes into play here, because one of the withdrawal symptoms of nicotine is impaired focus.
People are more impulsive when they feel lousy. Both strength training and aerobic exercise decrease symptoms of depression in recovering alcoholics and smokers who have quit.
The researchers characterized self-regulation as a resource that can be depleted but also recharged like a muscle. Essentially, the more you use this faculty, the stronger it gets. And exercise is by far the best form of self-regulation we have.
How much exercise you need depends, of course, on how severe the habit is. But I would say thirty minutes of vigorous aerobic exercise five days a week is the bare minimum if you want to root out an addiction. To begin, however, it’s best if you can do something every day, because the exercise will keep you occupied and focused on something positive. I have seen a lot of people who bury themselves in addiction when they lose their jobs, so if you are unemployed, having exercise in place is essential. And while I often suggest that people exercise in the morning, if your goal is to break a habit such as having a drink every night when you come home, exercising in the evening is probably a better strategy. You can use the aerobic shot for a different kind of buzz.
If you haven’t been in the habit of exercising, it can be helpful to join a gym or hire a personal trainer, because spending the money is a strong motivator. If you have an addiction to food, try a quick walk around the block or a few minutes with a jump rope or even a set of thirty jumping jacks—anything to snap your mind out of the cycle of thinking about the reward.
“The week before my period I have to do an hour of cardio four days a week or I can’t stand myself.”
Several years ago a group of German researchers decided to test whether exercise would have any impact on the painful process of labor. They brought a stationary bicycle into the labor suite. Somehow they found fifty women who agreed to pedal for periods of twenty minutes, rate their pain levels, and have their blood tested for endorphins right up until they gave birth. Most of them (84 percent) said contractions were less painful during exercise than at rest, and their ratings were inversely proportional to endorphin levels. The researchers concluded that, “exercising on a bicycle ergometer during labor seems to be safe for the fetus, a stimulus to uterine contractions, and a source of analgesia.”
For 10 to 15 percent of new mothers like Stacy, everything seems fine at first, but then postpartum depression strikes, and it can stick around for a year or more.
From this perspective, exercise might be even more effective for new moms experiencing depression than for the general population because it normalizes neurotransmitter levels.
Laurin found that women over sixty-five who reported higher levels of physical activity were 50 percent less likely than their inactive peers—women and men alike—to develop any form of dementia.
People always want to know what type of aerobic activity is best, and the answer is whatever is going to allow you to build it into your lifestyle.
The advice that surprises people the most, I think, is that it’s important to keep up exercise during pregnancy, a recommendation that has finally been endorsed by the American College of Obstetricians and Gynecologists. Its guidelines specify thirty minutes of moderate-intensity aerobic activity every day during pregnancy for healthy women. Obviously, it’s important to get clearance directly from your obstetrician, but it’s safe for most women. Likewise, I can’t stress enough the importance of picking up your routine as soon as possible after the baby is born, ideally within a few weeks. Although it seems contradictory, moving will actually reduce fatigue. And for women like my patient Stacy, it melts away anxiety and depression. When women are younger, one of the big motivations to exercise is to stay trim, and that’s fine. Use whatever gets you going. But the message I want to leave you with is that even as your body changes, exercise will keep your mind firm and taught. And in this state of mental fitness, you’ll be well equipped to handle the hormonal fluctuations that every woman experiences throughout her life.
The average seventy-five-year-old suffers from three chronic medical conditions and takes five prescription medicines, according to the Centers for Disease Control (CDC). Among those over sixty-five, most suffer from hypertension; more than two-thirds are overweight; and nearly 20 percent have diabetes (which triples the chance of developing heart disease). The leading killers are heart disease, cancer, and stroke; together they account for 61 percent of all deaths in this age group. We already know that smoking, inactivity, and eating poorly are root causes of these bodily diseases. Likewise, the latest research is clear about how lifestyle influences the mental hazards that come with aging. The same things that kill the body kill the brain, which neuroscientist Mark Mattson, of the National Institute on Aging, sees as a positive. “I think the good news—if we take it seriously—is that many of the same factors that can reduce our risk for cardiovascular disease and diabetes also reduce the risk for age-related neurodegenerative disorders,” he says. The measures we would take to guard against diabetes, for example, also balance insulin levels in the brain and shore up neurons against metabolic stress. Running to lower our blood pressure and strengthen our heart also keeps the capillaries in the brain from collapsing or corroding and causing a stroke. Lifting weights to prevent osteoporosis from devouring our bones releases growth factors that make dendrites bloom. Conversely, taking omega-3 fatty acids for mental acuity strengthens our bones. The mental and physical diseases we face in old age are tied together through the cardiovascular system and metabolic system. A failure of these underlying connections explains why people who are obese are twice as likely to suffer from dementia, and why those with heart disease are at far greater risk of developing Alzheimer’s, the most common form of dementia.
“Paradoxically,” says Mattson, “it’s good that cells be periodically subjected to mild stress because it improves their ability to cope with more severe stress.”
Exercise is preventive medicine as well as an antidote. Age happens. There’s nothing you can do about the why, but you can definitely do something about the how and the when.
The hormones estrogen, in women, and testosterone, in men, decrease with age, and this can lead to a shift in mood or a loss of vigor and interest. Also, one of the reasons depression is a risk factor for dementia is that it has corrosive effects on the hippocampus: if we’re under constant stress and the hormone cortisol stays elevated, it eats away at our synapses.
Exercise is obviously a great way to challenge yourself and your brain, and all the better if it puts you in contact with other people and gets you out and about. Consider a recent study from the Rush Alzheimer’s Disease Center. 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. And it’s clear from the studies at Duke University that exercise reduces depression and is even better than Zoloft at keeping people from relapsing.
Here’s how exercise keeps you going:
Exercise increases levels of insulin-like growth factor (IGF-1), which regulates insulin in the body and improves synaptic plasticity in the brain. By drawing down surplus fuel, exercise also bolsters our supply of BDNF, which is reduced by high glucose.
Exercise, naturally, counteracts obesity on two fronts: it burns calories, and it reduces appetite.
Exercise makes proteins that fix the damage and delay the process.
Staying mobile also allows us to stay involved, keep up with people, and make new friends; social connections are important in elevating and sustaining mood.
Population studies bear this out: The most consistent risk factor for cancer is lack of activity.
Second, part of the immune system’s job is to activate cells that fix damaged tissue. When it’s out of whack, these damaged spots fester, and you are left with chronic inflammation.
Exercise brings the immune system back into equilibrium so it can stop inflammation and combat disease.
More women every year die from hip fractures—a vulnerability of osteoporosis—than from breast cancer. Women reach peak bone mass at around thirty, and after that they lose about 1 percent a year until menopause, when the pace doubles. The result is that by age sixty, about 30 percent of a woman’s bone mass has disappeared. Unless, that is, she takes calcium and vitamin D (which comes free with ten minutes of morning sun a day) and does some form of exercise or strength training to stress the bones. Walking doesn’t quite do the job -save that for later in life. But as a young adult, weight training or any sport that involves running or jumping will counteract the natural loss.
It’s important to have plans and goals and appointments, and this is why sports such as golf and tennis are great. They require constant monitoring and motivation to improve.
The one proven way to live longer is to consume fewer calories—at least if you’re a lab rat. In experiments in which rodents eat 30 percent fewer calories, they live up to 40 percent longer than animals allowed to eat as much as they want.
Walking should be perfectly adequate, but do it outside with a friend if possible. Whatever you choose, try to find something that you will enjoy over the long haul. Try a more intense pace for two days a week—70 to 75 percent of your maximum—for twenty to thirty minutes. If you haven’t been exercising, you’ll want to build up to this speed, and that’s fine. Consistency is probably more important than intensity.
Hit the weights or resistance machines twice a week, doing three sets of your exercises at weights that allows you to do ten to fifteen repetitions in each set. This is critical for preventing and counteracting osteoporosis: even if you do all the aerobic training in the world, your muscles and bones will still atrophy with age. A Tufts University study of women fifty to seventy years old showed that those who participated in strength training for a year added 1 percent of bone density in their hips and spine, while the sedentary group lost 2.5 percent of the density in those areas.
Focus on these abilities twice a week for thirty minutes or so. Yoga, Pilates, tai chi, martial arts, and dance all involve these skills, which are important to staying agile.
Volunteering is beneficial because it involves social contact, which is inherently challenging for the brain. Anything that keeps you in contact with other people helps you live better and longer—statistics show a tight inverse relationship between sociability and mortality. Novel experiences demand more from your brain, and this builds its ability to compensate. You get more Miracle-Gro, more connections, more neurons, and more possibilities.
The point I’ve tried to make—that exercise is the single most powerful tool you have to optimize your brain function—is based on evidence I’ve gathered from hundreds and hundreds of research papers, most of them published only within the past decade.
Body and brain are connected. Why not take care of both?
The upper end of high-intensity exercise is sometimes painful but always powerful territory that has gained a lot of scientific interest recently.
That said, I do agree with experts like Duscha that the most important thing is to do something. And to start. This last bit may sound obvious, but for the sedentary—especially if inactivity is due to depression—taking that first step may seem impossible. For some people it’s a catch-22: they can’t start because they don’t have the energy, and they don’t have the energy because they’re not exercising. I’ve seen this happen with some of my patients, and it’s a very real problem, not simply an issue of willpower. The key is to attack the business of starting as a challenge in itself.
It’s crucial to build in recovery time, so your body and brain have the opportunity to bounce back.
One of the key differences between moderate and high-intensity exercise is that once you get closer to your maximum, and especially when you get into the anaerobic range, the pituitary gland in your brain unleashes human growth hormone (HGH). This is what life-extension groups call the fountain of youth. The levels of HGH naturally secreted into the bloodstream decrease over your life span, so that by middle age they dwindle to a tenth of what they were during childhood, for both women and men. And a sedentary lifestyle exacerbates this decline: high levels of cortisol, insulin resistance, and excess fatty acids in the bloodstream all clamp down further on the hormone’s release. HGH is the body’s master craftsman, burning belly fat, layering on muscle fiber, and pumping up brain volume. Researchers believe it can reverse the loss of brain volume that naturally occurs as you age. Athletes such as Olympic sprinters and football players are essentially spiking their levels of HGH when they do interval training, doping the natural way.
High-intensity exercise toughens you up, both physiologically and psychologically. It’s the reason why we climb mountains and sign up for fitness boot camps and go on Outward Bound trips. Yet you don’t need to go to such extremes to reap the rewards I’m talking about. One study from the University of Bath, in England, found that adding a single spurt of sprinting for thirty seconds—in this case while pedaling on a stationary bike—generated a sixfold increase in HGH, which peaked two hours after the sprint. And a recent study by neurologists at the University of Muenster, in Germany, reported that interval training improves learning ability. During the course of a forty-minute treadmill run, volunteers did two three-minute sprints (separated by two minutes at a lower intensity). Compared with subjects who stayed at low intensity, the sprinters had significantly higher increases in BDNF as well as norepinephrine.
Doing squats doubled HGH levels compared with running at high intensity for thirty minutes.
Every day is best but that even intermittent exercise works wonders.
Back in Naperville, Zientarski teaches cooperation, not competition, but for some adults being part of a team can get them hooked, whether it’s a three-on-three city basketball program, an adult soccer league, or Masters swimming. Maybe walking with the one you love will turn out to be the key, or maybe you’ve always wanted to learn tae kwon do, or maybe, like Naperville Central graduate Jessie Wolfrum, you’ll discover a passion for the infinite challenge of rock climbing (which requires a partner).
Numbered list of actionable takeaways.