Numerous studies have shown how collision sports, such as football, affect the brains of players, but little research has been conducted to see if contact sports, such as soccer and basketball, also affect young players' brains. Research at Canada's St. Michael's Hospital found that the answer is "yes."

Researchers at St. Michael's Hospital performed preseason brain scans on varsity athletes who were divided into three types of sports — collision, contact, and non-contact.

Collision sports include football where there is routine, purposeful body-to-body contact. Contact sports, which include soccer, basketball, and field hockey, allow contact, but contact isn't an essential part of the game.  Non-contact sports include volleyball.

Scans found that the brains of athletes who participated in collision or contact sports showed changes to structure and function when compared to those who played non-contact sports, and the amount of changes were greater in people who played sports with a greater risk of body contact.

The differences included changes in the structure of the brain's white matter — the fibers that connect different parts of the brain and allow them to communicate with one another. In addition, the studies also found chemical markers typically associated with brain injury, compared to athletes in non-contact sports.

Study results were published in the journal Frontiers of Neurology.

A 2016 study from UT Southwestern Medical Center in Dallas, Texas, found that brain changes can be seen in high school football players after only one season.

For the study, players underwent pre- and post-season imaging by a specialized MRI scan which could measure the brain's white matter, structural changes in white matter, and changes in function.

None of the players had experienced a concussion during the study, but those who had been subjected to head impacts showed the greatest brain changes. The differences were similar to those seen in car crashes.

 According to the National Federation of State High School Associations, football is the No. 1 high school participation sport in the U.S. with more than 1 million playing in the 2015-2016 school year.