| |
Exercise Improves The Brain - How HIV Causes Brain Damage
|
| |
| |
Download the PDF here
Potential cause of HIV-associated dementia revealed - (07/13/12) AIDS: 15 May 2011
How HIV Affects the Brain-new study: Human Immunodeficiency Virus Type 1 Alters Brain-Derived Neurotrophic Factor Processing in Neurons (BDNF) - (07/12/12) The Journal of Neuroscience, July 11, 2012
---------------------------------
"the running rats had much higher levels of brain-derived neurotrophic factor (B.D.N.F.), a growth factor that is thought to help spark neurogenesis, than the sedentary rats. So did the rats with weights tied to their tails"
Neurogenesis (birth of neurons) is the process by which neurons are generated from neural stem and progenitor cells. Most active during pre-natal development, neurogenesis is responsible for populating the growing brain with neurons. Numerous findings link stress-relieving activities (learning, exposure to a new yet benign environment, and exercise) to increased levels of neurogenesis.
Exercise Improves Brain Function
www.natap.org/2010/newsUpdates/011911_02.htm
--------------------------------
"Regular endurance exercise, like running or cycling, increases the muscles' production of this enzyme"....2 drugs made mice run more
How Working the Muscles May Boost Brainpower
www.natap.org/2012/HIV/050912_05.htm
May 9, 2012
------------------------------
Exercise improves cognition for two reasons:
· Exercise increases oxygen flow into the brain, which reduces brain-bound free radicals. One of the most interesting findings of the past few decades is that an increase in oxygen is always accompanied by an uptick in mental sharpness.
· Exercise acts directly on the molecular machinery of the brain itself. It increases neurons' creation, survival, and resistance to damage and stress.
Exercise | Brain Rules |
------------------
Not only is exercise smart for your heart and weight, but it can make you smarter and better at what you do.
July 14 2012 WebMD
Train Your Brain With Exercise
http://www.webmd.com/fitness-exercise/features/train-your-brain-with-exercise
Anyone with a brain exercises these days, but did you know exercise can return the favor and train your brain? Not only is exercise smart for your heart and weight, but it can make you smarter and better at what you do.
"I like to say that exercise is like taking a little Prozac or a little Ritalin at just the right moment," says John J. Ratey, MD, an associate professor of psychiatry at Harvard Medical School and author of A User's Guide to the Brain. "Exercise is really for the brain, not the body. It affects mood, vitality, alertness, and feelings of well-being."
Stephen C. Putnam, MEd, took up canoeing in a serious way to combat the symptoms of adult ADHD (attention deficit hyperactivity disorder). Then he wrote a book, titled Nature's Ritalin for the Marathon Mind, about the benefits of exercise on troublesome brain disorders such as ADHD, a neurological/behavioral condition resulting in hyperactivity and the inability to focus on tasks.
Putnam cites studies of children who ran around for 15 to 45 minutes before class and cut their ants-in-the-pants behavior by half when they got to class. As with most exercise, the effects were relatively lasting -- smoothing out behavior two to four hours after the exercise.
Putnam also points to some preliminary animal research that suggests that exercise can cause new stem cells to grow, refreshing the brain and other body parts. According to Ratey, exercise also stimulates nerve growth factors. "I call it Miracle-Gro for the brain," he says.
How Exercise Trains the Brain
Christin Anderson, MS, wellness and fitness coordinator of the University of San Francisco, explains that exercise affects many sites within the nervous system and sets off pleasure chemicals such as serotonin and dopamine that make us feel calm, happy, and euphoric.
In other words, if you don't want to wait for those good feelings to come by accident (if they do), you can bring them on by exercising.
"When one exercises," Anderson says, "you can think more clearly, perform better, and your morale is better. This is pure science -- stimulate your nervous system and function at a higher level."
Effects of Exercise on Depression
Almost everyone has heard of the "fog of war," but the "fog of living" is depression. "Depression affects memory and effectiveness (not to mention the ability to get up, get dressed, and function)," Anderson says. "If you can control your physiology, you can relax, focus, and remember."
In a study reported in the Journal of Sports Medicine and Physical Fitness in 2001, 80 young male and female volunteers were tested for mood and then did aerobics for an hour. Of the 80, 52 were depressed before the exercise. That group was the most likely to benefit, reporting a reduction in anger, fatigue, and tension. They also felt more vigorous after the workout.
A well-known study was done at Duke University involving 150 people 50 or older who had been diagnosed with depression. They were divided into three groups and given either exercise as a treatment for four months, the antidepressant drug Zoloft, or a combination of the two.
At the end of the four months, all three groups felt better. But the researchers didn't leave it there. They checked again in six months, and the exercise group had relapsed at significantly lower rates than the Zoloft or combination groups. In fact, the scientists felt that giving the Zoloft along with the exercise undermined the effects of the exercise, saying the combination group might have preferred to feel they had worked for their improvement rather than having to take a pill.
This doesn't mean, the researcher said, that exercise is a cureall for every case of depression. Seeking out the study showed motivation, and motivation can be hard to come by when you're depressed.
Bipolar disorder also does not seem to respond as well to exercise. On the other hand, anxiety disorders sometimes respond even more quickly.
If You Want to Try Exercise as a Brain Trainer
Single bouts of exercise can reduce anxiety for several hours afterward, although there may be a lag time before the good feeling sets in if exercise is too intense (good news for those who find fanatical, prolonged, "check your pulse" exercise unappealing).
Therefore, low to moderate forms of exercise are recommended for brain training. Ratey recommends 8 to 12 minutes a day of sweating and breathing-hard exercise (60% of maximum heart rate) for brain training.
Anderson says a minimum would be 30 minutes of moderate exercise, walking, hiking, or swimming, three times a week. Half an hour to an hour, four to five times a week would be even better. For those who want to be REALLY on the ball, 90 minutes five to six times a week would not be out of line, she says.
Anderson recommends two sessions a day for this purpose, rather than one big heaving workout. "Swim for 20 minutes in the morning, then walk at night," she advises. "Right after hard, intense exercise, you may not be as acute. Overtraining can set off enzymes that can lead to fatigue, which is the enemy of alertness."
Anderson also says the type of exercise you select depends on your personality. It may be the opposite of what you'd expect. "If you're a 32-year-old male, work 70 hours a week, play ball twice on the weekend and jog daily," she says, "you may need to do some yoga to improve your mental acuity." Some coaches, she points, out actually have to get people to relax to find their "edge." Meditation can also be a great complement to exercise, she adds. Then: "Do what you enjoy. That's important."
"You want to ready your brain for learning," Ratey says. For that to happen, all the chemicals must "jog" into place.
--------------------------------------
"Exercise Makes Healthier Brains"
"exercise prompts increases in something called brain-derived neurotropic factor, or B.D.N.F"
How Exercise Could Lead to a Better Brain - NYTimes.com
http://www.nytimes.com/2012/04/22/magazine/how-exercise-could-lead-to-a-better-brain.html?pagewanted=all
animals that exercised, whether or not they had any other enrichments in their cages, had healthier brains and performed significantly better on cognitive tests than the other mice. Animals that didn't run, no matter how enriched their world was otherwise, did not improve their brainpower in the complex, lasting ways that Rhodes's team was studying.
Even more heartening, scientists found that exercise jump-starts neurogenesis. Mice and rats that ran for a few weeks generally had about twice as many new neurons in their hippocampi as sedentary animals. Their brains, like other muscles, were bulking up.
But it was the ineffable effect that exercise had on the functioning of the newly formed neurons that was most startling. Brain cells can improve intellect only if they join the existing neural network, and many do not, instead rattling aimlessly around in the brain for a while before dying.
Exercise, on the other hand, seems to make neurons nimble When researchers in a separate study had mice run, the animals' brains readily wired many new neurons into the neural network. But those neurons didn't fire later only during running
Just how exercise remakes minds on a molecular level is not yet fully understood, but research suggests that exercise prompts increases in something called brain-derived neurotropic factor, or B.D.N.F., a substance that strengthens cells and axons, fortifies the connections among neurons and sparks neurogenesis. Scientists can't directly study similar effects in human brains, but they have found that after workouts, most people display higher B.D.N.F. levels in their bloodstreams.
Few if any researchers think that more B.D.N.F. explains all of the brain changes associated with exercise. The full process almost certainly involves multiple complex biochemical and genetic cascades. A recent study of the brains of elderly mice, for instance, found 117 genes that were expressed differently in the brains of animals that began a program of running, compared with those that remained sedentary, and the scientists were looking at only a small portion of the many genes that might be expressed differently in the brain by exercise.
Whether any type of exercise will produce these desirable effects is another unanswered and intriguing issue. "It's not clear if the activity has to be endurance exercise," says the psychologist and neuroscientist Arthur F. Kramer, director of the Beckman Institute at the University of Illinois and a pre-eminent expert on exercise and the brain. A limited number of studies in the past several years have found cognitive benefits among older people who lifted weights for a year and did not otherwise exercise. But most studies to date, and all animal experiments, have involved running or other aerobic activities.
Whatever the activity, though, an emerging message from the most recent science is that exercise needn't be exhausting to be effective for the brain. When a group of 120 older men and women were assigned to walking or stretching programs for a major 2011 study, the walkers wound up with larger hippocampi after a year. Meanwhile, the stretchers lost volume to normal atrophy. The walkers also displayed higher levels of B.D.N.F. in their bloodstreams than the stretching group and performed better on cognitive tests.
In effect, the researchers concluded, the walkers had regained two years or more of hippocampal youth. Sixty-five-year-olds had achieved the brains of 63-year-olds simply by walking, which is encouraging news for anyone worried that what we're all facing as we move into our later years is a life of slow (or not so slow) mental decline.
-------------------------------------------------
How Exercise Fuels the Brain
NY Times February 22, 2012
Moving the body demands a lot from the brain. Exercise activates countless neurons, which generate, receive and interpret repeated, rapid-fire messages from the nervous system, coordinating muscle contractions, vision, balance, organ function and all of the complex interactions of bodily systems that allow you to take one step, then another.
This increase in brain activity naturally increases the brain's need for nutrients, but until recently, scientists hadn't fully understood how neurons fuel themselves during exercise. Now a series of animal studies from Japan suggest that the exercising brain has unique methods of keeping itself fueled. What's more, the finely honed energy balance that occurs in the brain appears to have implications not only for how well the brain functions during exercise, but also for how well our thinking and memory work the rest of the time.
For many years, scientists had believed that the brain, which is a very hungry organ, subsisted only on glucose, or blood sugar, which it absorbed from the passing bloodstream. But about 10 years ago, some neuroscientists found that specialized cells in the brain, known as astrocytes, that act as support cells for neurons actually contained small stores of glycogen, or stored carbohydrates. And glycogen, as it turns out, is critical for the health of cells throughout the brain.
In petri dishes, when neurons, which do not have energy stores of their own, are starved of blood sugar, their neighboring astrocytes undergo a complex physiological process that results in those cells' stores of glycogen being broken down into a form easily burned by neurons. This substance is released into the space between the cells and the neurons swallow it, maintaining their energy levels.
But while scientists knew that the brain had and could access these energy stores, they had been unable to study when the brain's stored energy was being used in actual live conditions, outside of petri dishes, because brain glycogen is metabolized or burned away very rapidly after death; it's gone before it can be measured.
That's where the Japanese researchers came in. They had developed a new method of using high-powered microwave irradiation to instantly freeze glycogen levels at death, so that the scientists could accurately assess just how much brain glycogen remained in the astrocytes or had recently been used.
In the first of their new experiments, published last year in The Journal of Physiology, scientists at the Laboratory of Biochemistry and Neuroscience at the University of Tsukuba gathered two groups of adult male rats and had one group start a treadmill running program, while the other group sat for the same period of time each day on unmoving treadmills. The researchers' aim was to determine how much the level of brain glycogen changed during and after exercise.
Using their glycogen detection method, they discovered that prolonged exercise significantly lowered the brain's stores of energy, and that the losses were especially noticeable in certain areas of the brain, like the frontal cortex and the hippocampus, that are involved in thinking and memory, as well as in the mechanics of moving.
The findings of their subsequent follow-up experiment, however, were even more intriguing and consequential. In that study, which appears in this month's issue of The Journal of Physiology, the researchers studied animals after a single bout of exercise and also after four weeks of regular, moderate-intensity running.
After the single session on the treadmill, the animals were allowed to rest and feed, and then their brain glycogen levels were studied. The food, it appeared, had gone directly to their heads; their brain levels of glycogen not only had been restored to what they had been before the workout, but had soared past that point, increasing by as much as a 60 percent in the frontal cortex and hippocampus and slightly less in other parts of the brain. The astrocytes had "overcompensated," resulting in a kind of brain carbo-loading.
The levels, however, had dropped back to normal within about 24 hours.
That was not the case, though, if the animals continued to exercise. In those rats that ran for four weeks, the "supercompensation" became the new normal, with their baseline levels of glycogen showing substantial increases compared with the sedentary animals. The increases were especially notable in, again, those portions of the brain critical to learning and memory formation Ñ the cortex and the hippocampus.
Which is why the findings are potentially so meaningful - and not just for rats.
While a brain with more fuel reserves is potentially a brain that can sustain and direct movement longer, it also "may be a key mechanism underlying exercise-enhanced cognitive function," says Hideaki Soya, a professor of exercise biochemistry at the University of Tsukuba and senior author of the studies, since supercompensation occurs most strikingly in the parts of the brain that allow us better to think and to remember. As a result, Dr. Soya says, "it is tempting to suggest that increased storage and utility of brain glycogen in the cortex and hippocampus might be involved in the development" of a better, sharper brain.
Given the limits of current technologies, brain glycogen metabolism cannot be studied in people. But even so, the studies' findings make D.I.Y. brain-fuel supercompensation efforts seem like an attractive possibility. And, according to unpublished data from Dr. Soya's lab, the process may even be easy.
He and his colleagues have found that "glycogen supercompensation in some brain loci" is "enhanced in rats receiving carbohydrates immediately after exhaustive exercise." So for people, that might mean that after a run or other exercise that is prolonged or strenuous enough to leave you tired, a bottle of chocolate milk or a banana might be just the thing your brain is needing.
| |
| |
| |
|
|
|
