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The Impact of Exercise on the Brain
By Jason von Stietz, M.A.
November 26, 2016


Most students of psychology have learned of the study by Marian Diamond in which a group of rats living in an enriched environment had a thicker, more developed cortex than rats living in an impoverished environment. If the brains of rats can be changed, a questions is raised: What can change the brains of humans? Former student of Diamond, neuroscientist Wendy Suzuki has devoted her career to the effect of physical exercise on the human brain. Suzuki’s life and research was discussed in a recent article in The Huffington Post: 


Devoted to solving intricate physiological questions about the brain for almost her entire adult life, Wendy Suzuki, a neuroscientist at New York University, was proud of her work. But the long hours dedicated to research eventually left her feeling socially isolated and physically weak.


Taking up a habit of regularly visiting the gym changed all that — so profoundly that she decided to also change the focus of her studies and become a beginner researcher in the neuroscience of exercise at 51 years old. That meant giving up the reputation she had built over 25 years to enter a field where no one knew her.


“It was a hard decision and it was scary,” Suzuki said. “But once I made the decision I knew it was the right one.”


She also thought it was a particularly good decision because the results of her work, which focuses on understanding the effects of exercise on the brain, could quickly lead to tangible benefits.


“The thing that was really exciting and appealing is that this was the kind of research that could immediately be applied to helping people live their life better,” she said. 


We’ve long known that exercise makes for a healthier, fitter body. But its similar effects on the brain have only come to light in recent years. In fact, just the idea that the brain can change at all in response to experiences is something that had not garnered much evidence until the late 20th century. One of the first experiments to show the flexibility of the brain was done in 1972, when researchers put mice in a fun cage equipped with running wheels and toys, and found the cortex area of the rodents’ brains grew thicker, whereas it didn’t in mice kept in a dull, small cage.


Later it was found that although we are endowed with a set amount of long-lasting neurons, new neurons could still be born in adulthood. More importantly, this occurs in the hippocampus, a critical structure for memory and learning. And what can boost the generation of new neurons there? Aerobic exercise.


The hippocampus is one of the primary targets of neurodegenerative diseases such as Alzheimer’s. So building up the hippocampus over a lifetime could potentially delay the effects of diseases.


“Exercise is not going to cure Alzheimer’s or dementia but it anatomically strengthens two of the key targets of both those diseases, the hippocampus and the prefrontal cortex,” Suzuki said. “Your hippocampus will be bigger if you exercise regularly, so that means that it’s going to take that much longer for the plaques and tangles of Alzheimer’s disease to cause behavioral effects. That means months, or hopefully years, of higher cognitive function.”


The creation of new neurons, or neurogenesis, doesn’t happen overnight, however. Neurons don’t just pop up fully formed and fully integrated. They are born as immature cells and take several months to grow.


But that’s not to say that all positive effects will be delayed by three or four months if you start exercising now. As many people have noticed firsthand, exercising also makes the mind sharper and attention more focused. That’s because another brain area heavily affected by aerobic exercise is the prefrontal cortex, an area in charge of high-level cognition, executive functions, decision-making and attention. 


Exactly how it happens is not fully known, but it seems that the prefrontal cortex is actually relaxing during intense physical activity. It then gets a rebound increase in blood flow after the exercise, enabling it to work at full speed. It’s also possible that the same bodily changes that help new neurons grow in the hippocampus are also at work in the prefrontal cortex and help grow glial cells and blood vessels.


So which type of exercise is best from the brain’s point of view? Here’s what we can tell from research so far:


Mood: Walking, aerobic exercise and high-intensity interval training can improve your mood.


“We recently did a study comparing the three. All three of them improved mood but the one that did the most was walking. That’s good news for people who don’t have a high-level aerobic regime on hand,” Suzuki said. 


Memory: The best evidence for hippocampal neurogenesis is continuous aerobic exercise.


“You have to get your heart rate up. So a good 45-minute workout,” Suzuki said.


Attention: Aerobic exercise is again the best option if you want to boost attention. But unlike with memory, the improvements are more acute and come faster. Jogging, biking and treadmill running are all good options for getting a boost in the prefrontal cortex. 


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Trauma Impacts Brains of Boys and Girls Differently
By Jason von Stietz, M.A.
November 19, 2016


A recent study from researchers at Stanford University School of Medicine found differences in the brain structures of boys and girls suffering from traumatic experiences. Interestingly, brains scans found no differences between the brains of boys and girls in the healthy control group. However, in the brains of those who experienced trauma there were significant differences in the volume and surface of the anterior circular sulcus. The study was discussed in a recent article in Medical Xpress: 


Among youth with post-traumatic stress disorder, the study found structural differences between the sexes in one part of the insula, a brain region that detects cues from the body and processes emotions and empathy. The insula helps to integrate one's feelings, actions and several other brain functions.


The findings will be published online Nov. 11 in Depression and Anxiety. The study is the first to show differences between male and female PTSD patients in a part of the insula involved in emotion and empathy.


"The insula appears to play a key role in the development of PTSD," said the study's senior author, Victor Carrion, MD, professor of psychiatry and behavioral sciences at Stanford. "The difference we saw between the brains of boys and girls who have experienced psychological trauma is important because it may help explain differences in trauma symptoms between sexes."


Smaller insula in traumatized girls


Among young people who are exposed to traumatic stress, some develop PTSD while others do not. People with PTSD may experience flashbacks of traumatic events; may avoid places, people and things that remind them of the trauma; and may suffer a variety of other problems, including social withdrawal and difficulty sleeping or concentrating. Prior research has shown that girls who experienced trauma are more likely to develop PTSD than boys who experience trauma, but scientists have been unable to determine why.


The research team conducted MRI scans of the brains of 59 study participants ages 9-17. Thirty of them—14 girls and 16 boys—had trauma symptoms, and 29 others—the control group of 15 girls and 14 boys—did not. The traumatized and nontraumatized participants had similar ages and IQs. Of the traumatized participants, five had experienced one episode of trauma, while the remaining 25 had experienced two or more episodes or had been exposed to chronic trauma.


The researchers saw no differences in brain structure between boys and girls in the control group. However, among the traumatized boys and girls, they saw differences in a portion of the insula called the anterior circular sulcus. This brain region had larger volume and surface area in traumatized boys than in boys in the control group. In addition, the region's volume and surface area were smaller in girls with trauma than among girls in the control group.


Findings could help clinicians


"It is important that people who work with traumatized youth consider the sex differences," said Megan Klabunde, PhD, the study's lead author and an instructor of psychiatry and behavioral sciences. "Our findings suggest it is possible that boys and girls could exhibit different trauma symptoms and that they might benefit from different approaches to treatment."


The insula normally changes during childhood and adolescence, with smaller insula volume typically seen as children and teenagers grow older. Thus, the findings imply that traumatic stress could contribute to accelerated cortical aging of the insula in girls who develop PTSD, Klabunde said.


"There are some studies suggesting that high levels of stress could contribute to early puberty in girls," she said.


The researchers also noted that their work may help scientists understand how experiencing trauma could play into differences between the sexes in regulating emotions. "By better understanding sex differences in a region of the brain involved in emotion processing, clinicians and scientists may be able to develop sex-specific trauma and emotion dysregulation treatments," the authors write in the study.


To better understand the findings, the researchers say what's needed next are longitudinal studies following traumatized young people of both sexes over time. They also say studies that further explore how PTSD might manifest itself differently in boys and girls, as well as tests of whether sex-specific treatments are beneficial, are needed.


The work is an example of Stanford Medicine's focus on precision health, the goal of which is to anticipate and prevent disease in the healthy and precisely diagnose and treat disease in the ill.


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