Researchers used an advanced MRI (Magnetic Resonance Imaging) technique to analyze changes in brain white matter of 32 adult amateur soccer players who head balls 436 times a year on average.

　　The study found players who head football quite frequently -- with 1,000 or more a year -- showed abnormalities similar to traumatic brain injuries suffered in car accidents.

　　"This is the first study to look at the effects of heading on the brain using sophisticated diffusion tensor imaging," said Dr. Michael Lipton, a leading 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 added.

　　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.

　　The findings come in the wake of mixed reports on the so-called "cognitive" consequences of frequently heading soccer balls at practice.

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

　　Dr. Lipton agreed neuropsychological damage from headers would be hard for a coach or physician to notice since cognitive problems develop gradually, and even players might not be aware of mild memory loss.

　　"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."