CHAPTER 13

Build a Better Brain

Working out seems to unlock a medicine cabinet in your brain. Much is made of the “runner's high,” the brain's release of feel-good chemicals that happens during a lengthy, challenging run. Even more important, factors that protect, strengthen and encourage growth of neurons are released during a workout. Exercisers have improved memory, and fewer symptoms of mood and emotional disorders.

PART 1 Bulk Up Your Brain

Not so long ago, conventional wisdom held that you couldn't do much to change your brain. Once your brain reached its full size, any brain cells you destroyed were gone forever, we believed. In the past couple of decades, research has illuminated the brain's power to grow, evolve and make new connections. One protein that makes this possible, brain-derived neurotrophic factor (BDNF), is released in greater volumes during aerobic exercise. READ MORE

BDNF has been nicknamed “brain Miracle-Gro,” and it's no wonder. Its effects include protecting existing brain cells, encouraging their growth, helping neurons form new connections and pathways, stimulating the growth of new neurons (called neurogenesis) from stem cells in the hippocampus, and solidifying long-term memories (called, well, learning). BDNF is an important agent in the phenomenon of brain plasticity—the ability of the brain to alter its signaling pathways in response to something new. During exercise, bloodstream levels of BDNF increase significantly. BDNF works in concert with several other growth factors to buff up the brain's structure, functionality, and potential.LESS

PART 2 Lift, Run, Learn, Remember

Structural changes to the brain after exercise are dramatic. The real proof of exercise's impact is in actual cognitive performance, which is usually measured by testing people before and after they start an exercise program. The results are very clear: exercise improves test results regardless of age or gender.

Researchers at the University of Illinois at Urbana-Champaign have conducted important research on the relationship between exercise and the brain. One of its top researchers, Arthur Kramer, and colleagues measured the aerobic fitness of 165 people aged 59 to 81. They also took MRI scans of the subjects' brains and tested their spatial reasoning, which involves visualizing objects and making logical conclusions about how they might be altered. The adults who were most aerobically fit tended to do significantly better on the spatial reasoning test. There was also a clear connection between fitness and the size of the brain's hippocampus, a key player in long-term memory storage. READ MORE

In Canada, a group of 155 women ages 65 to 75 were divided into two groups. One began a regular weight-training program. The other performed toning and balance exercises twice a week. After one year, the strength-training group improved their scores on tests of executive function, planning and decision-making tasks largely carried out by the brain's prefrontal cortex, right behind your forehead. The control group did not show significant improvement.

In another study out of Urbana-Champaign, researchers took a look at this phenomenon in younger subjects. Researcher Charles Hillman recruited a group of kids aged 9 and 10 and assessed their fitness on a treadmill run. The kids also took a cognitive test that gauged their ability to filter out extraneous information. Then their brains were scanned. The results: Those who were most fit tended to have better test performance and larger basal ganglia, which helps coordinate actions and thoughts. Another study of 9- and 10-year-olds tested their fitness level and scanned their brains, but took a different test which assessed their complex memory skills. The fittest kids in this group had larger hippocampi. “What we found so far is that high-fit kids have more tissue in their basal ganglia, an area involved in the interplay between cognition and willed action, and the hippocampus, which is vital to certain kinds of memory,” Hillman told TheVisualMD.com. “There may be other factors. But this correlation was very strong.” LESS

PART 3 Healthy Body, Healthy Mind

Have you ever gone to the gym to blow off steam? Taken a brisk walk around the block to shake a nasty encounter? Without referring to scientific studies or learning the names of the neurotransmitters involved, many people already know that exercise will help them relieve stress. It also alleviates some symptoms of depression and anxiety by signaling the release of good-mood brain chemicals. READ MORE

Endorphins, the body's home-grown pain relievers, are known to block pain signals to the brain, which brings about their feel-good effect. Just as endorphins are the body's version of morphine, endocannabinoids are its homemade version of the active ingredient in cannabis, or marijuana. Both are released into the bloodstream in great volume after intense aerobic exercise. Both bring about feelings of euphoria, calm and well-being. But there's an important difference: Molecules of endorphins are too big to pass the blood-brain barrier, which is where a tiny brain blood vessel hits a dead end. At the blood-brain barrier, molecules that are small enough can pass through and have an effect on brain tissue. Since the exercise-induced flood of endorphins from the bloodstream cannot get through, some researchers speculate that endorphins made right inside the brain may be responsible for runner's high. But others are now believe that endocannabinoids, which are small enough to pass through that barrier, are the true source of an exerciser's “runner's high.”

Exercise improves mood and controls anxiety in many ways. It unleashes the calming neurotransmitters serotonin, which regulates anxiety, and gamma-aminobutyric acid (GABA), which inhibits neural activity in the brain. A study of subjects over 50 who had been diagnosed with major depressive disorder established three research groups. One group started an aerobic exercise training program. A second took the antidepressant medication Zoloft. The third group combined the two interventions—some exercise and Zoloft. After 16 weeks, all three groups showed improvement in their depression symptoms. The group taking the drug had more immediate improvement, but by the end of the research period it was clear that the exercise-only group had improved just as much as the other two. LESS