Researchers at Albert Einstein College of Medicine of Yeshiva University have shown that soccer players who frequently head the ball have brain abnormalities resembling those found in patients with concussion (mild traumatic brain injury).
On average, soccer players head the ball six to 12 times during games, where balls can travel at speeds of more than 50 miles per hour. During practice drills, players commonly head the ball 30 or more times. The impact from a single heading is unlikely to cause traumatic brain damage such as laceration of nerve fibers. But scientists have worried that cumulative damage from heading's repeated subconcussive impacts might be clinically significant. "Repetitive heading could set off a cascade of responses that leads to degeneration of brain cells over time," noted Dr. Lipton.
... findings pertaining to the most frequent headers in our study showed white-matter abnormalities similar to what we've seen in patients with concussion," said Dr. Lipton.
"Our study provides compelling preliminary evidence that brain changes resembling mild traumatic brain injury are associated with frequently heading a soccer ball over many years," said Dr. Lipton. [emphasis mine]