December 7, 2011, 12:01 AM
A New Worry for Soccer Parents: Heading the Ball
By GRETCHEN REYNOLDS
What happens inside the skull of a soccer player who repeatedly heads a soccer ball? That question motivated a provocative new study of the brains of experienced players that has prompted discussion and debate in the soccer community, and some anxiety among those of us with soccer-playing offspring.
For the study, researchers at the Albert Einstein College of Medicine in New York recruited 34 adults, men and women. All of the volunteers had played soccer since childhood and now competed year-round in adult soccer leagues. Each filled out a detailed questionnaire developed especially for this study to determine how many times they had headed a soccer ball in the previous year, as well as whether they had experienced any known concussions in the past.
Then the players completed computerized tests of their memory and other cognitive skills and had their brains scanned, using a sophisticated new M.R.I. technique known as diffusion tensor imaging, which can find structural changes in the brain that would not be visible during most scans.
The researchers found, according to data they presented at a Radiological Society of North America meeting last month, that the players who had headed the ball more than about 1,100 times in the previous 12 months showed significant loss of white matter in parts of their brains involved with memory, attention and the processing of visual information, compared with players who had headed the ball fewer times. (White matter is the brain’s communication wiring, the axons and other structures that relay messages between neurons.)
This pattern of white matter loss is “similar to those seen in traumatic brain injury,” like after a serious concussion, the researchers reported, even though only one of these players reported having ever experienced a concussion.
The players who had headed the ball about 1,100 times or more in the past year were also substantially worse at recalling lists of words read to them, forgetting or fumbling the words far more often than players who had headed the ball less often.
“Based on these results, it does look like there is a potential for significant effects on the brain from frequent heading,” says Dr. Michael L. Lipton, associate director of the Gruss Magnetic Resonance Research Center at Einstein and senior author of the study.
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For decades, there have been intimations that heading could have undesirable consequences, including reports in the late 1980s and early ’90s of memory deficits in retired, professional Scandinavian soccer players. But those studies depended on players’ slippery recall of the number of times they had headed during their entire careers and didn’t take into account alcohol use or a history of severe concussions, and the findings generally have been dismissed as unreliable.
Then last year, Elizabeth Larson, a researcher at Humboldt State University in California, carefully tracked the heading history and cognitive health of 51 male and female soccer players at the school, a Division II program, over the course of a full collegiate season. She found that the players who headed the ball most often during the season, whether in practices or games, performed significantly worse on tests of visual memory, including the ability to recall shapes and images, than they had at the start of the season. Those players also reported more headaches and episodes of dizziness than other players.
“Physiologically, it makes sense” that verbal and visual recall might be affected by frequent heading, said Ms. Larson, who now coordinates the North Coast Concussion Program at the university. Those memories are partially processed in the front and rear of the brain, “the areas that bump against the skull when you head the ball,” she says.
In confirmation, the new imaging study showed that the frontal lobe, just behind the forehead, and the temporo-occipital region, at the bottom-rear of the brain, were the areas displaying the most damage among the high-frequency headers.
So what’s a soccer parent to do?
“What our research shows is that there appears to be a threshold” ? about 1,100 or so balls headed in a single year, a substantial number ? “beyond which heading may be problematic,” Dr. Lipton says. “Below that threshold, it appears that heading is safe. So our research is actually optimistic, I think.”
Many questions, however, remain ? especially about the impact of heading in young players, which has not to date been studied. “On the one hand, kids’ brains are developing fast, so they might experience more problems” than adults, Dr. Lipton says. “On the other hand, their brains are renowned for their plasticity, so maybe they’ll recover better. We just don’t know.”
The practical significance of any brain damage is also uncertain. None of the players who scored poorly on cognitive tests in the Einstein or Humboldt State studies had noticed any memory problems. “The effects, such as they are, seem to be subtle,” Ms. Larson says.
Still, she recommends some preemptive steps, based on the current science. “There is a growing consensus that kids younger than 12 shouldn’t be heading,” she says, and parents should monitor the number of heading repetitions and any accompanying symptoms in older children. Ask your child if he or she experiences headaches or dizziness after practice and, if so, “check with the coach about reducing the frequency of heading drills.
“No one is suggesting that heading should be outlawed,” she concludes. But science and common sense both indicate that “it’s almost certainly not a good idea to practice heading over and over and over.”
'Heading' a Soccer Ball Could Lead to Brain Injury
At A Glance
Researchers used diffusion tensor imaging to determine if heading a soccer ball could cause brain injury.
Players who most frequently headed the ball exhibited abnormalities in five brain regions.
Players who headed the ball at least 1,000 to 1,500 times per year showed detectable white matter injury.
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CHICAGO?Using diffusion tensor imaging (DTI) to study the effects of soccer 'heading,' researchers have found that players who head the ball with high frequency have brain abnormalities similar to those found in traumatic brain injury (TBI) patients. Results of their study were presented today at the annual meeting of the Radiological Society of North America (RSNA).
Michael L. Lipton, M.D., Ph.D.
Heading, in which players field the soccer ball with their head, is an essential part of the game and the focus of many training drills.
"Heading a soccer ball is not an impact of a magnitude that will lacerate nerve fibers in the brain," said Michael L. Lipton, M.D., Ph.D., associate director of the Gruss Magnetic Resonance Research Center at the Albert Einstein College of Medicine and medical director of MRI services at Montefiore Medical Center in New York. "But repetitive heading could set off a cascade of responses that can lead to degeneration of brain cells."
DTI, an advanced magnetic resonance (MR) technique, allows researchers to assess microscopic changes in the brain's white matter, which is composed of millions of nerve fibers called axons that act like communication cables connecting various regions of the brain. DTI produces a measurement, called fractional anisotropy (FA), of the movement of water molecules along axons. In healthy white matter, the direction of water movement is fairly uniform and measures high in FA. When water movement is more random, FA values decrease.
"Abnormally low FA within white matter has been associated with cognitive impairment in patients with TBI," Dr. Lipton said.
Dr. Lipton and colleagues conducted DTI on 32 amateur soccer players (average age: 30.8 years), all of whom have played the sport since childhood. The researchers estimated how often each soccer player headed the ball on an annual basis and then ranked the players based on heading frequency. They then compared the brain images of the most frequent headers with those of the remaining players and identified areas of the brain where FA values differed significantly.
"Between the two groups, there were significant differences in FA in five brain regions in the frontal lobe and in the temporooccipital region," Dr. Lipton said. "Soccer players who headed most frequently had significantly lower FA in these brain regions."
The five regions identified by the researchers are responsible for attention, memory, executive functioning and higher-order visual functions.
To assess the relationship between the frequency of heading and white matter changes, the researchers also compared the magnitude of FA in each brain region with the frequency of heading in each soccer player.
"Our goal was to determine if there is a threshold level for heading frequency that, when surpassed, resulted in detectable white matter injury," Dr. Lipton said.
The analysis revealed a threshold level of approximately 1,000 to 1,500 heads per year. Once players in the study surpassed that level, researchers observed a significant decline in their FA in the five identified brain regions.
"What we've shown here is compelling evidence that there are brain changes that look like traumatic brain injury as a result of heading a soccer ball with high frequency," Dr. Lipton said. "Given that soccer is the most popular sport worldwide and is played extensively by children, these are findings that should be taken into consideration in order to protect soccer players."
Coauthors are Namhee Kim, Ph.D., Molly Zimmerman, Ph.D., Richard Lipton, M.D., Walter Stewart, Ph.D., Edwin Gulko, M.D., and Craig Branch, Ph.D.
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Note: Copies of RSNA 2011 news releases and electronic images will be available online at RSNA.org/press11 beginning Monday, Nov. 28.
RSNA is an association of more than 48,000 radiologists, radiation oncologists, medical physicists and related scientists committed to excellence in patient care through education and research. The Society is based in Oak Brook, Ill. (RSNA.org)
Editor's note: The data in these releases may differ from those in the printed abstract and those actually presented at the meeting, as researchers continue to update their data right up until the meeting. To ensure you are using the most up-to-date information, please call the RSNA Newsroom at 1-312-949-3233.
For patient-friendly information on brain imaging, visit RadiologyInfo.org.
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