The Revolutionary New Science on Exercise and the Brain
Lindsay Orbeta, MS, RDRegistered DietitianVisa 101 Series
+We are born “movers”
modern human genome remains unchanged
since time of hunter-gatherers
sedentary lifestyle poses biggest threat to our continued survival
65% adults overweight or obese
10% U.S. population has Type 2 Diabetes
inactivity kills brain cells
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Presentation Notes
Intro: In today’s technology driven world, it’s easy to forget that we are born movers. This is because we’ve engineered movement right out of our lives. We are no longer hunter-gatherers, yet the modern human genome remains virtually unchanged since that time. The sedentary character of modern life is a disruption to our nature, and poses one of the biggest threats to our continued survival. - 65% of our nations adults are now overweight or obese - 10% of the population has Type 2 Diabetes We’re literally killing ourselves, but what’s more problematic- because virtually no one recognizes it —inactivity is killing our brain power, too.
+The brain is an adaptable organ
Exercise can reverse depression and age-related diseases
Research from Duke University in 2000 showed exercise is better than Zoloft at treating depression
Darwin: learning is the survival mechanism we use to adapt to constantly changing environments
Plasticity: the brain can be molded by input like a muscle can be sculpted by weights
Brain is not ‘hard-wired’
Presenter
Presentation Notes
Exercise unleashes a cascade of neurochemicals and growth factors that can reverse depression and age-related diseases. A decade ago, researchers from Duke University made the New York Times with a study showing that exercise is better than Zoloft at treating depression. If only exercise came in a pill form, this would have made the front page and hailed as the blockbuster drug of the century. Every time our muscles contract, proteins travel through the bloodstream and into the brain, where they play pivotal roles in our highest thought processes. Why should you care about how well 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 hearing me speak about, and how much of it you soak up has a lot to do with weather or not you were physically active this morning before coming into work. Darwin taught us that learning is the survival mechanism we use to adapt to constantly changing environments. When we learn a French word or a new dance step, our brain cells morph to encode the information, and the memory physically becomes part of the brain. But what we now understand, is that the brain is flexible- more like Play-doh than porcelain. It’s an adaptable organ that can be molded by input in much the same way a muscle can be sculpted by lifting barbells. This concept of plasticity is fundamental to understanding how exercise optimizes brain function. Far from being hard-wired; the brain is constantly being re-wired. Today my aim is to teach you how to be your own electrician
+Neural Anatomy 101
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First, well start with a bit of neural anatomy. The junction between 2 brain cell branches is called the synapse. When we have a thought, an electrical signal shoots down the axon (or the outgoing branch), and then
+Neurotransmitter
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a neurotransmitter (such as serotonin or dopamaine) -- carries the message across the synaptic gap in chemical form. The receiving branch is called the dendrite- this is where the neurotransmitter plugs into a receptor (like a key into a lock). This opens up ion channels in the cell membrane to turn the cell back into electricity….
+
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An that electrical impulse is represented here in orange light. This is another neural impulse traveling down the next cell’s axon. Each cell fires another signal, repeating this process. The more often a certain connection is activated, the stronger the attraction becomes. This is what is meant when neuroscientists say “neurons that fire together, wire together”. Repeated activation, or practice, causes synapses to swell and make stronger connections. Say you’re learning a new word in Spanish. The first time you hear it, nerve cells are recruited for a new circuit, and fire a signal between one another. If you never practiced that word again, the attraction between synapses involved naturally diminishes, and you forget.
80% of signaling in the brain is carried out by 2 neurotransmitters: Glutamate stirs up activity by beginning the cascade, whereas GABA (gamma-amino butyric acid) clamps down on activity. There are also regulatory neurotransmitters, serotonin, norepinephrine and dopamine. Serotonin influences mood, impulsivity, anger and aggressiveness. (Remember that serotonin is also created when we eat carbohydrates or drink alcohol, and is a key component in explaining sugar addiction, alcoholism and drug addiction, as well as depression). Norepinephrine amplifies signals that influence attention, peception, motivation and arousal. Dopamine is involved in learning, reward, attention and movement. Most of us have heard of the drug Ritalin, which is used to treat ADHD. Ritalin works by raising dopamine levels, and this is how it calms the mind and lowers “noise” in the brain.
+Neurogenesis
We do
grow new brain cells!
Neurons born as blank-slate stem cells
Must plug into cell network <28 days
For a cell to survive, it must
integrate into the
‘signaling community’
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For most of the 20th century, we thought the brain was hard-wired once fully developed in adolescence, meaning we’re born with all the neurons we’re going to get. Remember when your Mom used to scare you away from underage drinking by telling you “alcohol kills brain cells, and they never grow back!?” Well, they do grow back- by the thousands. The process is called neurogenesis. Neurons are born as blank-slate stem cells, and if they don’t plug into the network within 28 days, these fledgling cells die. The neurons need a job -or specific mission- in order to survive- just like that old saying, “use it or lose it”. In order for a cell to survive, it must integrate and become a member of the signaling community.
+brain-derived neurotropic factor (BDNF)
BDNF:
builds & maintains cell’s circuitry
nourishes brain neurons like a fertilizer
BDNF allows synapses to:
process, associate, remember and contextualize info
BDNF applied to neurons in a petri dish sprouts new dendritic branches
BDNF is “Miracle Grow”
for the brain!
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Aside from neurotransmitters, there is another class of proteins that have been shown to govern the mind. The most prominent is brain-derived neurotropic factor (BDNF). BDNF actually builds and maintains the cell’s circuitry, or the infrastructure itself. BDNF is found in the hippocampus, an area of the brain related to memory and learning. BDNF nourishes brain neurons like a fertilizer, Specifically, it gives the synapses the ability to process information, associate and remember it, and then put it into context. A neuron is like a tree that instead of leaves, has synapses along its dendritic branches, and eventually new branches can sprout. Researchers knew in the 1990’s that if they sprinkled BDNF onto neurons in a petri dish, the cells automatically sprouted new branches. That’s why BDNF is now thought of as “Miracle Grow” for the brain.
+BDNF and exercise
0 2 4 7Nights running
per week
BDNF
levels
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One of the first studies looking at BDNF was in exercising mice. Mice were given running wheels in their cages so they could voluntarily exercise each night; rather than treadmills- which would have been forced exercise. It was imperative that exercise be voluntary, or else it would be considered an imposed stress. It turns out that rodents inherently enjoy physical activity- they ran several kilometers each night. The mice were put into 4 groups: mice running for 2, 4 or 7 nights per week, and the control group- which had no running wheel. The mice then received brain injections of a molecule that binds to BDNF. The brain scans revealed that- not only did the running rodents have significantly greater levels of BDNF compared to the sedentary mice, but the farther each mouse ran- the greater their BDNF levels were.
+
BDNF
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What’s more, the elevated BDNF was fond in the hippocampus- the area of the brain needed for learning, and an area highly vulnerable to degenerative disease. These studies demonstrated a direct biological connection between movement and cognitive function.
+Insulin Growth Factor 1
(IGF1)
Released by the muscles after prolonged activity
~90 mins exercise, when glycogen is low
Glucose is sole energy source for the brain
IGF-1 in the brain NOT related to fuel management-
but to learning
Evolutionary adaptation to locate food in the environment?
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Brain-derived neurotropic factor – or BDNF- gathers in reserve pools near our synapses, and is unleashed when we get our blood pumping. In the process, a number of hormones are called into action to help. The first of these is called Insulin Growth Factor-1 , or “IGF-1”. IGF-1 is released by the muscles after prolonged activity, when they are in need of a fuel source. This tends to occur mostly around 90 minutes of continued exercise, as that’s when glycogen stores run low. Glucose is not only a major fuel for the contracting muscle— it is the sole energy source for the brain. IGF-1 works with the hormone insulin to deliver glucose to the brain cells. What’s interesting though- the role of IGF-1 in the brain is not related to fuel management- but to learning, presumably so we can remember where to locate food in the environment. This makes perfect sense in light of evolution- When we were prehistoric men, we needed fuel to learn, and we needed learning to find a source of food.
+Vascular Endothelial Growth Factor (VEGF)
builds capillaries and blood vessels in the brain
provides greater delivery of oxygen and nutrients
lowers the permeability of BBB
opens up ‘filter’
into the brain, allowing
more factors through during exercise
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The second hormone that assists BDNF is called Vascular Endothelial Growth Factor , or VEGF. When we engage in higher-intensity exercise, our metabolic system is said to be in an anaerobic state- or short of oxygen supply. VEGF goes to work by building more capillaries and blood vessels in the brain; allowing a greater delivery of oxygen and nutrients to neurons. VEGF is also vital to neurogenesis, because it lowers the permeability of the blood-brain barrier. This means it liberalizes the filter into the brain, allowing more factors through during exercise.
+Fibroblast Growth Factor (FGF-2)
Enhances growth of new brain tissue
blood flow shifts back to brain immediately after intense exercise
* Consider a 15 minute fast-paced run at lunch time;
this would be ideal time to focus on a project which demands sharp thinking/ complex analysis
Exercise improves the rate
of learning
people learn vocab words 20% faster following
exercise compared to before
exercise
rate of learning correlated to BDNF
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The third hormone released with BDNF is Fibroblast Growth Factor (FGF-2) FGF-2 is also increased during exercise and has been shown to facilitate the growth of new brain tissue. Although blood flow during intense exercise is shunted away from the brain and favors the contracting muscles, blood flow shifts back immediately after you finish exercising. So, if you knew you had to focus on a project that demanded sharp thinking and complex analysis in the afternoon, a brief (15-20 min) -- but fast run would be the right exercise prescription On your lunch break. One of the prominent features of exercise is that it improves the rate of learning. In 2007, German researchers found that people learn vocabulary words 20% faster following exercise than they did before exercise, and the rate of learning correlated directly with BDNF levels.
+Exercise improves creativity
40 adults, aged 50-64 yrs, who either:
Jogged for 35 mins on treadmill @ 60-70% of H.R. max
Watched a movie
Participants then asked to give alternative uses for common objects
Only joggers had improved processing speed & cognitive flexibility
Have important morning brainstorming session scheduled?
try a short, intense workout before work
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A notable experiment in 2007 showed that cognitive flexibility improved after a 35-minute treadmill session at 60-70% of maximum H.R. (For a 35 year old person, this would be approximately the equivalent of a HR of 130 bpm) 40 adults, aged 50-64 yrs were assigned to one of 2 groups: Half the subjects watched a movie beforehand and the other half ran on the treadmill. All subjects were then asked to rattle off alternative uses for common objects, like a newspaper, besides reading. Examples are wrapping fish, lining a bird-cage etc. Only the runners had a markedly improved processing speed and cognitive flexibility. This refers to our ability to produce a steady flow of creative thoughts and answers as opposed to regurgitating usual responses. So, if you have an important brainstorming session scheduled in the morning, you would greatly benefit from a short, intense workout Before coming into work. Examples would include jumping rope, plyometrics, etc.
+Exercise prescription
Endurance exercise creates a thicker myelin sheath around nerve fibers.
improves impulse speed & circuit efficiency
Complex motor skills which engage nerve cells throughout the brain:
rock-climbing, soccer, tennis
gymnastics, plyometrics
yoga, ballet, pilates, salsa
Presenter
Presentation Notes
How much exercise do I need to do? Endurance exercise has been shown to create a thicker myelin sheath around the nerve fibers. This is a fatty layer that improves the speed at which an impulse travels, and in turn- the circuits’ efficiency. It’s not just aerobic exercise that’s important, but also mixing in activity which demands coordination beyond just putting one foot in front of the other. The following activities really work to engage nerve cells throughout the brain: I’m talking about complex motor skills, such as rock-climbing, plyometrics, soccer, gymnastics, yoga, ballet, swimming the butterfly stroke, laying tennis, or doing pilates, or learning salsa dance. All of these practices engage nerve cells throughout the brain.
In one experiment, running rats were compared to rats who were taught to walk across a balance beam or climb ladders. After 2 weeks of training, the acrobatic rats had a 35% increase of BDNF in the cerebellum, whereas the running rats had none in that area. This finding demonstrated the importance of including skill acquisition and not just aerobic exercise. While aerobic exercise promotes neurogenesis, we need challenging movements in order to create complex synaptic connections, so they can be recruited by other areas of the brain and used for thinking.
+
BDNF
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Presentation Notes
A major paradox is that our ability to adapt and grow doesn’t happen without stress. Stress is essentially a threat to the body’s equilibrium- it’s a challenge to react. Any degree of stress activates fundamental brain systems that manage attention, energy and memory. Regular aerobic exercise teaches the body to manage stress because it raises the ‘trigger point’ of a physical reaction. This means that it also raises the neural threshold for stress. Here’s how: When a nerve cell is called into action, glucose is taken into the powerhouse of the cell- the mitochondria. This converts it into a useable fuel called ATP, and just as with the burning of any fuel, waste by-products are produced. This is known as oxidative stress, or the generation of free radicals. Free radicals are unstable atoms with a rogue electron that attempts to destabilize every other cell in the body. BDNF (which is activated in exercise) increases the production of antioxidants in the cell as well as protective proteins.
+atrial natriuretic peptide (ANP)
ANP =
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Cardiologists have recently discovered a hormone called atrial natri-uretic peptide (ANP), produced by cardiac muscle tissue. Remember- the heart is also a muscle! Apparently, ANP directly tempers the body’s stress response by putting the brakes on a part of the brain called the HPA axis, which quiets noise in the brain. As heart increases during exercise, so does ANP. This is thought to be another explanation for how physical activity relieves stress.
+Exercise and metabolic health
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We all know that exercises increases blood flow, and within every blood cell, there is oxygen. The cells require oxygen to convert glucose into ATP to feed themselves. One of the ways exercise optimizes energy usage is by triggering the production of more receptors for insulin. When we are inactive, GLUT-4 transporters are located in the center of the muscle cell. As soon as the muscles become active, these transporters migrate to the surface of the cell, acting as receptors for insulin to bind to. Once insulin binds, the GLUT-4 takes in glucose and transports it back down into the mitochondria to be burned. Well, regular aerobic exercise increases not only the number of GLUT-4 transporters, but also translocates them- meaning the receptors stay there at the cell’s surface. These adaptations help the body make more economical use of blood glucose. People at risk of Type 2 diabetes or who have hyper-insulinemia would greatly benefit from this adaptation, as it improves insulin sensitivity and allows the cells to more efficiently use a smaller amount of glucose. Exercise also increases IGF-1, which further improves insulin-sensitivity.
+Exercise and cancer
23/35 studies showed an increased risk of breast cancer for inactive women
physically-active people have a 50% less chance of developing colon cancer
Active men > 65yrs have a 70% lower chance of developing advanced form of prostate cancer
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Exercise and cancer study outcomes Dr. Ratey reviewed 35 oncology studies in this book. Of those 35 studies, showed a statistically-significant increased risk of breast cancer for inactive women physically-active people have a 50% less chance of developing colon cancer- the only cancer directly linked to sedentary lifestyle and consumption of red meat Active men over 65 have a 70% lower chance of developing the advanced, typically fatal form of prostate cancer
+Effect of exercise on depression and anxiety
Exercise breaks down adipose tissue > free fatty acids
Fats compete with tryptophan for a slot on transport proteins into the brain
Tryptophan in the brain is a building block for serotonin
Serotonin is our built-in Prozac
Creates immediate sense of reward
& well-being
BDNF also boosts serotonin levels
Presenter
Presentation Notes
When we go from rest to exercise, the body breaks down triglycerides (or fat stores), liberating them into the bloodstream as free fatty acids (FFA). These FFA compete with tryptophan- one of the 8 essential dietary amino acids- for a slot on transport proteins into the brain. As this happens, the concentration of tryptophan builds up in the blood, and finally pushes through the blood-brain barrier to equalize it’s levels. Once inside the brain, it becomes a building block for serotonin— our built-in Prozac, or feel-good neurochemical. This creates an immediate sense of reward and well-being. Additionally, exercise ramps up BDNF, which also boosts serotonin levels to calm us down.
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8,023 residents in Alameda County followed for 23 years
Surveyed residents about their health and lifestyles in
1965, 1974 and 1983
Healthy-people who became inactive were 1 ½
x more likely to have depression by 1983 than those who exercised regularly
Sedentary individuals who became active were no more likely to become depressed than those who were active at the start
Changing your exercise habits changes your risk for depression!
Exercise and depression
Presenter
Presentation Notes
A landmark research project out of UC Berkeley followed 8,023 residents in Alameda County, and tracked their health and lifestyle factors for 26 years. -- This is one of the longest-term population studies we have to date. Researchers started in 1965 by surveying residents about their lifestyles, then checked back in with them in 1974 and 1983. Of all the people with NO signs of depression at the beginning, those who became inactive over the next 9 years were 1 ½ times more likely to have depression by 1983 than people who exercised regularly. On the other hand, those who started off as sedentary, but increased their activity level within the first 9 years- were no more likely to be diagnosed with clinical depression by 1983 than those who were physically active to begin with! In other words, changing your exercise habits changes your risk for developing depression.
+Exercise better than Prozac?
16-week trial called SMILE
Standard Medical Intervention and Long-term Exercise
all 156 subjects had depression
3 groups: Zoloft, exercise, or combination of both
Exercisers walked or jogged @ 75-80% of aerobic capacity for 45 mins
Results:
All 3 groups showed a significant drop in depression
½ of each group went completely into remission
Presenter
Presentation Notes
In 1999, a study out of Duke University compared the effects of exercise and Zoloft on depression. This 16-week trial was called SMILE (Standard Medical Intervention and Long-term Exercise). Zoloft is in the same drug-class with Prozac— SSRI- or selective serotonin re-uptake inhibitors. All 156 subjects were diagnosed with depression, and were randomly assigned to one of 3 groups: Zoloft, exercise, or a combination of the 2. The exercise group was assigned to supervised walking or jogging , at 75-80% of their aerobic capacity, for 45 mins, including a 10-min warm up. Results: All 3 groups showed a significant drop in depression, and about ½ of each group went completely into remission from depression.
Capillary volume in memory area of the hippocampus increased 30%
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Studies like these have pushed the American Psychiatric Association to formally adopt exercise into its treatment guidelines for depression. It is suggested now that psychiatrists tell every patient to walk 3-5 miles/day or do some other form of vigorous exercise. Exercise boosts BDNF at least as much as anti-depressants, and sometimes more. At Colombia University in 2007, a study put subjects on a 3-month exercise regimen and then took pictures of their brains using a standard MRI machine, only manipulating the images to zoom in. This was a real breakthrough technology that allows scientists to see neurogenesis without slicing into the brain. Researchers were able to capture pictures of the newly formed capillaries after exercise training. They found that capillary volume in the memory area of the hippocampus increased by 30%, a truly remarkable change.
+In conclusion
Exercise has been shown to:
Initiate growth of new brain cells
Improve cognition, memory and concentration
Decrease depression, anxiety and stress
Exercise imparts self-mastery and self-confidence
Gives you an alternative to negative coping mechanisms for stress
The feeling of “needing to exercise daily”
is less about surviving and more about thriving!
Presenter
Presentation Notes
In conclusion With exercise, you gain a sense of self-mastery and self-confidence. As you develop awareness of your own ability to manage stress through exercise, you realize you have the power to not rely on negative coping mechanisms—such as drinking alcohol or eating comfort foods. If you can get to the point where you’re consistently saying to yourself that exercise is something you want to do, then you’re charting a course to a different future- one that’s less about surviving and more about thriving.
