TUESDAY, Nov. 29 (HealthDay News) -- Frequent "heading" of soccer balls by avid amateur players may cause brain damage leading to subtle but serious declines in thinking and coordination skills, a new study suggests.

For the study, researchers used an advanced MRI technique to analyze changes in brain white matter of 32 adult amateur soccer players who headed balls 436 times a year on average. Players who were high-frequency headers -- with 1,000 or more a year -- showed abnormalities similar to traumatic brain injuries suffered in car accidents, the study found.

"This is the first study to look at the effects of heading on the brain using sophisticated diffusion tensor imaging," said Dr. Michael Lipton, lead researcher and associate director of the Gruss Magnetic Resonance Research Center at the Albert Einstein College of Medicine in New York City.

"We found the real implication for players isn't from hitting headers once in a while, but repetitively, which can lead to degeneration of brain cells," he said.

The researchers compared neurological images of study participants, whose average age was 31, and found those with the highest volume of headers had abnormalities in five areas of the brain, responsible for attention, memory, physical mobility and high-level visual functions.

Negative changes started occurring in the neuro-regions when players surpassed threshold levels of about 1,000 to 1,500 headers a year, according to the study slated for presentation Tuesday at the annual meeting of the Radiological Society of North America, in Chicago.

The findings come in the wake of mixed reports on the so-called "cognitive" consequences of frequently heading soccer balls at practice and during games in a popular sport played by millions of children and young adults worldwide. Cognitive is a term used to describe brain-based functions such as memory, thinking, learning and processing information. Previous research linked poor memory and motor function test results to one or more concussions caused by a player's head hitting a goal post, slamming into the ground or colliding with another player.

Dr. Chris Koutures, a pediatrician and sports medicine specialist in Anaheim Hills, Calif., said the retrospective imaging study was fascinating, but needs more data to effectively determine safe header limits, especially for younger players.

"We need an approach where we follow players down the road and count the headers in respect to age, head injuries, alcohol use and other factors," Koutures said. "This would be valuable information to share with players and their families."

Meanwhile, practicing proper heading technique -- striking the ball with the forehead as the head, neck and torso are set in a solid line without any twisting -- can reduce force on the head, Koutures said. Children are not developmentally ready to learn this skill until age 10 and shouldn't practice heading until then, he added.

His own review of previous research on youth soccer injuries, published in the February 2010 issue of Pediatrics, found no documented connection between repeated heading and long-term head injury or neurologic damage, Koutures said.

Lipton agreed the literature has sent inconsistent signals about the impact of heading on a player's health, adding there is now compelling preliminary evidence to look at the issue more closely.

Neuropsychological damage from headers would be hard for a coach or physician to notice since cognitive problems develop gradually. Even players might not be aware of mild memory loss, he said.

"We can't tell an individual today not to be heading a ball, but caution is a good thing," Lipton said. "We need more research for definitive answers and we have the advanced imaging tools to do it."

The research presents an opportunity for public health intervention once thresholds are established for the number of headers considered safe for players, Lipton said.

"There are threshold levels where we don't see brain abnormalities, which means heading is not absolutely bad," Lipton said. "Rules could be developed to alleviate adverse affects by limiting the number of headers allowed for certain age groups or skill levels of play."

The data and conclusions of research presented at medical meetings should be viewed as preliminary until published in a peer-reviewed journal.

More information

There's more on youth soccer injuries at the American Academy of Pediatrics.