Enhancing sleep after brain injury reduces brain damage, cognitive decline in rats

March 23, 2016

Science Daily/Society for Neuroscience

Enhancing sleep after a head injury may help prevent some damage to brain cells, according to a study. Researchers found that enhancing the slow-wave cycle of sleep after head trauma minimized damage to axons -- the thin extensions that nerve cells use to send signals to other cells -- and helped preserve normal brain function.

Traumatic brain injury is a major cause of death and disability worldwide. While brain cells at the site of impact are damaged immediately, many more cells can perish in the hours and days after the trauma as damaged axons succumb to injury. Studies suggest that widespread axonal injury contributes to many of the long-lasting problems with learning, memory, and movement commonly associated with head injuries. Molecular waste products also build up in the brain after head injury. Recent studies indicate the brain clears out this molecular buildup during the slow-wave stage of sleep where brain activity synchronizes into high-amplitude waves.

The researchers led by Daniela Noain and Christian Baumann investigated whether enhancing slow-wave sleep after a head injury could mitigate axonal injury in rats. Twenty-five rats received a blow to the prefrontal cortex, a brain area associated with decision-making and self-control. One-third of the injured rats were sleep-deprived for short periods of time as previous studies indicate, for a brief period of time afterward, sleep deprivation enhances slow-wave sleep. Another group was treated with sodium oxybate, a drug used to induce a slow-wave sleep-like state in narcolepsy patients. A third group received placebo.

One day after injury and continuing for the next five, researchers modulated the animals' sleep. Employing electroencephalography (EEG) recordings during treatment, they confirmed that the animals experienced slow-wave sleep enhancement as a result of treatment. Afterward, the rats took a memory test, and the team examined their brains for axonal damage, focusing on areas involved in learning and memory, including the hippocampus.

They found that rats receiving treatments to enhance slow-wave sleep were better able to recognize familiar objects than the untreated rats. In addition, the researchers found that levels of a biomarker for diffuse axonal injury were reduced nearly 80 percent in animals that had experienced enhanced sleep compared to untreated rats.

While further study is needed, the work suggests slow-wave sleep administered immediately after a brain injury helps block axon damage and preserve normal brain function, Baumann says.

"Despite the high prevalence of traumatic brain injury worldwide, very few effective treatments exist to mitigate the persistent impairment in memory and cognitive function," says Miranda Lim, a neurologist at Oregon Health & Science University who was not involved in the study. "This study provides important evidence that manipulating sleep may be a promising avenue to enhance recovery after TBI."

https://www.sciencedaily.com/releases/2016/03/160323082229.htm

Impact of repetitive heading in soccer needs more research, say experts

February 10, 2014

Science Daily/St. Michael's Hospital

Soccer is the most-popular and fastest-growing sport in the world and, like many contact sports, players are at risk of suffering concussions from collisions on the field.

But researchers warned in a paper published today that not enough attention has been given to the unique aspect of soccer -- the purposeful use of the head to control the ball -- and the long-term consequences of repetitive heading.

The literature review by Dr. Tom Schweizer, director of the Neuroscience Research Program of St. Michael's Hospital, was published in the journal Brain Injury.

More than 265 million people play soccer worldwide, including 27 million in North America. Due to the nature of the sport, players are particularly vulnerable to head and neck injuries. Most are caused by unintentional or unexpected contact, such as when a player collides with teammates, opponents or the playing surface.

There is significant concern in the sporting and medical worlds about the potential long-term cognitive and behavioral consequences for athletes who suffer acute or repeat concussions or multiple "sub-concussive" head impacts -- blows to the head not causing symptoms of concussions.

"The practice of heading, which might occur thousands of times over a player's career, carries unknown risks, but may uniquely contribute to cognitive decline or impairment in the short- or long-term," said Dr. Schweizer, a neuroscientist. "Thus, soccer players present a unique opportunity to study whether cumulative sub-concussive impacts affect cognitive functioning, similar to that of concussions."

Examining research papers that studied the incidence of concussion in soccer, he found that concussions accounted for 5.8 per cent to 8.6 per cent of total injuries sustained during games. One study found that 62.7 per cent of varsity soccer players had suffered symptoms of a concussion during their playing careers, yet only 19.2 per cent realized it. Another found that 81.8 per cent of athletes who had suffered a concussion had experienced two or more and that players with a history of concussion had a 3.15 times greater odds of sustaining another one than those who had never had a concussion. One study found concussions sustained during soccer accounted for 15 per cent of the total number of concussions in all sports. In particular, girls' soccer accounted for 8.2 per cent of sports-related concussions, the second highest sport after football.

Research papers that looked at the mechanism of injury found 41.1 per cent of concussions resulted from contact by an elbow, arm or hand to the head. One found that 58.3 per cent of concussions occurred during a heading duel. More females suffered concussions from player-to-surface and player-to-ball contact than males who had more player-to-player contact than females.

Defensemen and goalkeepers are at greatest risk of suffering a concussion, the study found. Dr. Schweizer said that for goalkeepers, the risk decreases as they get older and become more aware of where they are at any given time in relation to the goal posts. He said padding goal posts might be one way to reduce concussions in younger players who don't have such a developed sense of spatial relations.

Studies on the long-term effects of heading found greater memory, planning and perceptual deficits in forwards and defenders, players who execute more headers. One study found professional players reporting the highest prevalence of heading during their careers did poorest in tests of verbal and visual memory as well as attention. Another found older or retired soccer players were significantly impaired in conceptual thinking, reaction time and concentration. The few studies that used advanced imaging techniques found physical changes to the brains in players who had concussions.

Monica Maher, a co-author and University of Toronto master's degree student in neuroscience, said the researchers wanted to emphasize possible injury prevention methods.

"Use of protective headgear, limiting heading exposure or stressing proper heading technique in younger children and increasing concussion education are all suggestions to perhaps decrease the incidence of head injury and their subsequent effects in the long run," she said.

http://www.sciencedaily.com/releases/2014/02/140210114538.htm

Frequent 'heading' in soccer can lead to brain injury and cognitive impairment

November 29, 2011

Science Daily/Albert Einstein College of Medicine

Using advanced imaging techniques and cognitive tests, researchers have shown that repeatedly heading a soccer ball increases the risk for brain injury.

The researchers used diffusion tensor imaging (DTI), an advanced MRI-based imaging technique, on 38 amateur soccer players (average age: 30.8 years) who had all played the sport since childhood. They were asked to recall the number of times they headed the ball during the past year. (Heading is when players deliberately hit or field the soccer ball with their head.) Researchers ranked the players based on heading frequency and then compared the brain images of the most frequent headers with those of the remaining players. They found that frequent headers showed brain injury similar to that seen in patients with concussion, also known as mild traumatic brain injury (TBI).

The findings are especially concerning given that soccer is the world's most popular sport with popularity growing in the U.S., especially among children. Of the 18 million Americans who play soccer, 78 percent are under the age of eighteen. Soccer balls are known to travel at speeds as high as 34 miles per hour during recreational play, and more than twice that during professional play.

"These two studies present compelling evidence that brain injury and cognitive impairment can result from heading a soccer ball with high frequency," Dr. Lipton said. "These are findings that should be taken into consideration in planning future research to develop approaches to protect soccer players."

As there appears to be a safe range for heading frequency, additional research can help refine this number, which can then be used to establish heading guidelines. As in other sports, the frequency of potentially harmful actions in practice and games could be monitored and restricted based on confirmed unsafe exposure thresholds.

"In the past, pitchers in Little League Baseball sustained shoulder injuries at a rate that was alarming," Dr. Lipton noted. "But ongoing research has helped shape various approaches, including limits on the amount of pitching a child performs, which have substantially reduced the incidence of these injuries."

"Brain injury due to heading in children, if we confirm that it occurs, may not show up on our radar because the impairment will not be immediate and can easily be attributed to other causes like ADHD or learning disabilities," continued Dr. Lipton. "We, including the agencies that supervise and encourage soccer play, need to do the further research to precisely define the impact of excessive heading on children and adults in order to develop parameters within which soccer play will be safe over the long term."

http://www.sciencedaily.com/releases/2011/11/111129092420.htm

Routine head hits in school sports may cause brain injury

November 14, 2011

Science Daily/University of Rochester Medical Center

The brain scans of high school football and hockey players showed subtle injury -- even if they did not suffer a concussion -- after taking routine hits to the head during the normal course of play, according to a new study.

The research, reported online in the journal Magnetic Resonance Imaging, is preliminary, involving a small sample of athletes, but nonetheless raises powerful questions about the consequences of the mildest head injury among youths with developing brains, said lead author Jeffrey Bazarian, M.D., M.P.H., associate professor of Emergency Medicine at URMC with a special interest in sports concussions.

Measurements in the study at hand showed many changes in the brain of the player with the diagnosed concussion; however an intermediate level of changes also occurred among the players who reported anywhere from 26 to 399 total sub-concussive blows. The fewest changes occurred in the control group, as expected.

http://www.sciencedaily.com/releases/2011/11/111114133738.htm