Children's brains undergo noticeable changes after just one season of football, even if they were never diagnosed with a concussion, according to a new imaging study.

While there is no way to know whether the changes may lead to health problems down the road, the researchers found that the degree of change seen in the brain's white matter tracts was tied to the amount of exposure a child had to head impacts during play.

"It's really another study that suggests there are changes in the brain associated with all of these head impacts," said lead author Dr. Christopher Whitlow, of the Wake Forest School of Medicine in Winston-Salem, N.C.

He and his colleagues write in the journal Radiology that among U.S. contact sports, American football has a high rate of traumatic brain injury. A lot of focus has been placed on examining the role of brain injuries, such as concussions, on future health problems like the degenerative brain disease known as chronic traumatic encephalopathy (CTE).

"If we really want to understand what's going on at the end of the line for professional players, we need to be looking at the very beginning," Whitlow told Reuters Health. "That's our youth and high school players."

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For the new study, the researchers recruited 25 young football players between 8 and 13 years old. All participants were boys, and wore helmets during play with a device to measure hits to the head. The hits were confirmed by videos.

The boys also had specialized images of their brains taken before and after the football season. The researchers then analyzed those images for changes to the brain's white matter, which consists of bundles of nerve fibers connecting different parts of the brain.

Despite the boys having no symptoms or signs of concussion, the researchers found changes to the brain's white matter and its connection points after the season. The number of changes tracked with how many hits to the head the boys had taken during play.

"More exposure, more changes," Whitlow said. "Less exposure, less change."

The findings help confirm the results of past studies, said Dr. Jeffrey Bazarian, a professor of emergency medicine at the University of Rochester Medical Center in New York.

"We don't know for sure if these changes are bad," said Bazarian, who was not involved with the new study. "The only way to know this is if we follow these particular players over time."

While the lack of data on what these changes mean doesn't provide parents and coaches with a lot of information, he noted that other research has found six months of rest may be able to reverse some of these changes in some people-not all, however.

Young athletes may not want to take part in contact sports year round, said Bazarian. "Even though this study doesn't specifically say that, maybe the brain needs a break."

Parents can also help by watching their children practice and play to see if they're not acting normal after a hit to the head, said Whitlow. Additionally, it's important to have athletic and healthcare professionals on the field in order to help players.

Whitlow added that the benefits of sports like football need to be weighed against the potential risks.

For example, he said sports help young people develop leadership and teamwork skills. Additionally, there are the overall benefits of physical activity.

"I think we want to encourage our children to play sports," said Whitlow.

Bazarian said more research on this topic is crucial.

"A study like this really needs long-term follow up," he said.

Additionally, he said, most studies on this subject include only male participants. Females need to be in the studies to see if their brains respond differently.