before exercising, while the non-cycling group did not.
Five weeks later, with the cycling group continuing to cycle regularly, the team performed the tests again. They found that five weeks of cycling training increased BDNF levels and performance on the face-naming test, leading researchers to conclude that both acute and repeated exercise benefit the hippocampus.
Hippocampal Growth
Before and after images illustrate the type of growth that occurs in the hippocampus with vigorous exercise.
And the Cortex
Having a larger hippocampus, of course, is only part of the story. There’s plenty of evidence that exercise also increases the size of the cortex. One such study comes from Erickson and his colleagues, who examined 299 non-demented elderly people enrolled in the Cardiovascular Health Cognition Study, a longitudinal study that gathered data from 1988 to 2009. 6
Grouping the participants by the number of blocks they reported walking each week, the team studied participants’ initial physical assessments and then followed up with MRI scans nine years later. Four years after that, the team tested the participants for cognitive impairment and dementia.
The results were impressive. Those who’d walked regularly—about six to nine miles a week—had significantly more grey matter in the frontal, occipital, and hippocampal regions than those who walked less. Checking in thirteen years after participants’ initial assessments, Erickson’s team found that those who’d logged six to nine miles a week were far less likely to be cognitively impaired than those who walked the least.
Other research has shown similar changes in grey matter as well as in white matter associated with exercise. In one randomized clinical trial of fifty-nine cognitively healthy people between sixty and seventy-nine years old, for example, researchers at the University of Illinois found that study subjects who engaged in six months of aerobic exercise had more grey and white matter in the frontal and temporal lobes than when they’d started the study. Those who merely did toning and stretching exercises saw no such increase. 7
In 2012, University of California, Los Angeles (UCLA), researchers offered yet more evidence, presenting the findings of their study at the annual meeting of the Radiological Society of North America. Led by Dr. Cyrus Raji, the team examined the lifestyle habits and MRIs of 876 adults aged sixty-nine to ninety-five. Study subjects had varying degrees of cognitive health—some had normal cognitive function, some had mild impairment, and others had Alzheimer’s disease. The team calculated how many calories study subjects burned doing physical activities that ranged from sports, to yard work, to dancing, to cycling. Activity levels varied dramatically: those in the top twenty-fifth percentile burned about 3,400 calories a week, while those in the bottom twenty-fifth percentile burned just 384 calories a week on physical activity. 8
What was going on in the brain was also dramatic: those who’d burned the most calories had 5 percent more grey matter in the frontal, parietal, and temporal lobes—including the hippocampus—than those who burned the least.
A Combined Effect
We’re still working to understand exactly how exercise grows the brain. Increased BDNF no doubt is a major part of the story, especially when it comes to growth in the hippocampus. But there are other reasons exercise grows the brain.
For starters, exercise promotes cardiovascular health, helping the heart pump blood more efficiently to all parts of the body, the brain included. One way it does this is by increasing levels of high-density lipoproteins (HDLs), the “good cholesterol” in the blood, which allows blood to flow more freely. Another, as you’ll recall from the first pages of this book, is via a process called angiogenesis, the creation of new blood vessel branches. Exercise promotes angiogenesis. That means that as you exercise
Five weeks later, with the cycling group continuing to cycle regularly, the team performed the tests again. They found that five weeks of cycling training increased BDNF levels and performance on the face-naming test, leading researchers to conclude that both acute and repeated exercise benefit the hippocampus.
Hippocampal Growth
Before and after images illustrate the type of growth that occurs in the hippocampus with vigorous exercise.
And the Cortex
Having a larger hippocampus, of course, is only part of the story. There’s plenty of evidence that exercise also increases the size of the cortex. One such study comes from Erickson and his colleagues, who examined 299 non-demented elderly people enrolled in the Cardiovascular Health Cognition Study, a longitudinal study that gathered data from 1988 to 2009. 6
Grouping the participants by the number of blocks they reported walking each week, the team studied participants’ initial physical assessments and then followed up with MRI scans nine years later. Four years after that, the team tested the participants for cognitive impairment and dementia.
The results were impressive. Those who’d walked regularly—about six to nine miles a week—had significantly more grey matter in the frontal, occipital, and hippocampal regions than those who walked less. Checking in thirteen years after participants’ initial assessments, Erickson’s team found that those who’d logged six to nine miles a week were far less likely to be cognitively impaired than those who walked the least.
Other research has shown similar changes in grey matter as well as in white matter associated with exercise. In one randomized clinical trial of fifty-nine cognitively healthy people between sixty and seventy-nine years old, for example, researchers at the University of Illinois found that study subjects who engaged in six months of aerobic exercise had more grey and white matter in the frontal and temporal lobes than when they’d started the study. Those who merely did toning and stretching exercises saw no such increase. 7
In 2012, University of California, Los Angeles (UCLA), researchers offered yet more evidence, presenting the findings of their study at the annual meeting of the Radiological Society of North America. Led by Dr. Cyrus Raji, the team examined the lifestyle habits and MRIs of 876 adults aged sixty-nine to ninety-five. Study subjects had varying degrees of cognitive health—some had normal cognitive function, some had mild impairment, and others had Alzheimer’s disease. The team calculated how many calories study subjects burned doing physical activities that ranged from sports, to yard work, to dancing, to cycling. Activity levels varied dramatically: those in the top twenty-fifth percentile burned about 3,400 calories a week, while those in the bottom twenty-fifth percentile burned just 384 calories a week on physical activity. 8
What was going on in the brain was also dramatic: those who’d burned the most calories had 5 percent more grey matter in the frontal, parietal, and temporal lobes—including the hippocampus—than those who burned the least.
A Combined Effect
We’re still working to understand exactly how exercise grows the brain. Increased BDNF no doubt is a major part of the story, especially when it comes to growth in the hippocampus. But there are other reasons exercise grows the brain.
For starters, exercise promotes cardiovascular health, helping the heart pump blood more efficiently to all parts of the body, the brain included. One way it does this is by increasing levels of high-density lipoproteins (HDLs), the “good cholesterol” in the blood, which allows blood to flow more freely. Another, as you’ll recall from the first pages of this book, is via a process called angiogenesis, the creation of new blood vessel branches. Exercise promotes angiogenesis. That means that as you exercise
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