Additionally, the study published in the journal Radiology revealed that these athletes face a higher risk of developing memory and thinking problems.
The current study follows a previous one conducted by the same researchers that found that frequently heading the ball during soccer games can lead to brain injury. They noted that all five areas of the brain were affected.
Michael L. Lipton, M.D., Ph.D., associate director of Einstein's Gruss Magnetic Resonance Research Center and medical director of MRI services at Montefiore, the University Hospital and academic medical center for Einstein explained:
"We studied soccer players because soccer is the world's most popular sport. Soccer is widely played by people of all ages and there is concern that heading the ball - a key component of the sport - might damage the brain."
Soccer players head the ball six to 12 times on average during a game - and these balls can travel at speeds of over 50 miles per hour. During a practice session, players often head the ball more than 30 times.
The impact from a single heading will most likely not result in brain damage like laceration of nerve fibers, but scientists have worried that damage from repeated headings could be significant.
Dr. Lipton said "Repetitive heading could set off a cascade of responses that lead to degeneration of brain cells over time."
In order to examine possible brain injury from heading, the investigators used diffusion tensor imaging (DTI) - a modern MRI-based imaging technique - on 37 amateur adult soccer players (with a median age of 31 years), who had played soccer since childhood.
The subjects reported playing soccer for an average of 22 years and 10 months over the last year. Investigators categorized the players based on heading frequency and then compared the DTI brain images of the most frequent headers with those of the other players. Each participant also took part in cognitive testing.
DTI reveals the movement of water molecules within and along axons - the nerve fibers that make up the brain's white matter. The imaging method lets investigators calculate the uniformity of water movement (called fractional anisotropy, or FA) throughout the brain.
Unusually low FA within white matter suggest axon damage and has been previously linked to cognitive impairment in patients with traumatic brain injury.
Dr. Lipton said:
"The DTI findings pertaining to the most frequent headers in our study showed white-matter abnormalities similar to what we've seen in patients with concussion. Soccer players who headed the ball above a threshold between 885 to 1,550 times a year had significantly lower FA in three areas of the temporal-occipital white matter."
Players who perform over 1,800 headings per year were more likely to exhibit worse memory scores compared to subjects with fewer headings per year.
Dr. Lipton concluded:
"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. While further research is clearly needed, our findings suggest that controlling the amount of heading that people do may help prevent brain injury that frequent heading appears to cause."
Recurring head trauma in athletes has become a popular and worrisome topic. Repeated blows to the head during contact sports such as football are said to result in brain damage. The progression of the damage in athletes is characterized first by trouble focusing, followed by aggression and eventually dementia.
Written by Kelly Fitzgerald