Dr. Michael Lipton says, in smaller numbers, there does not seem to be a problem. But, when the number of headers reaches about 1,300 a year, research suggests the brain starts to suffer.
The study of 32 adult amateur soccer players used an advanced MRI technique to analyze changes in the brain. Those who did a lot of heading showed signs of trouble in areas of the brain responsible for attention and memory.
But Dr. Lipton stresses that this is not implying everyone who hits the soccer ball with their head will be hurt.
"The message of this study, if you do heading to excess that you may be at increased risk for having changes similar to concussion or mild traumatic brain injury," said Dr. Lipton. "And that's the key finding, understanding where that threshold lies and what the safe range of heading is the job for further research so we can make the game of soccer something people can do in a safe way."
Dr. Lipton says practice turns out to be a much bigger source of heading exposure than actual games.
This study was presented in Chicago Tuesday at the annual meeting of the Radiological Society of North America.