Playing contact sports such as soccer, basketball and field hockey may lead to greater effects on the brain of athletes, researchers say.

Researchers at St. Michael's Hospital performed pre-season brain scans of athletes and found that the athletes in collision and contact sports had differences in brain structure, function and chemical markers typically associated with brain injury, compared to athletes in non-contact sports.The study, published in the journal Frontiers of Neurology, found differences in the structure of the brain's white matter -- the fibre tracts that connect different parts of the brain and allow them to communicate with one another.Athletes in sports with higher levels of contact also showed signs of reduced communication between brain areas and decreased activity, particularly within areas involved in vision and motor function, compared to those in non-contact sports such as volleyball, the researchers said.

"This study fills an important gap in understanding how contact affects healthy brains, as a step towards better understanding why a small number of athletes in contact sports show negative long-term health consequences," said Tom Schweizer, head of the Neuroscience Research Programme and the paper's co-author.Most of the research in this area has focussed on the long-term effects for athletes in collision sports such as football and ice hockey, where players may be exposed to hundreds of impacts in a single season, the researchers noted.Less is known about the consequences of participating in contact sports where body-to-body contact is permitted but is not purposeful such as soccer, basketball and field hockey, the researchers added.