BBC News By Philippa Roxby image copyrightGetty Images image captionElite rugby players may be more at risk from brain changes than other people, a study suggests Sport has been allowed to "mark its own homework" on reducing the risks of brain injury, an MPs' inquiry says. Its report calls for a standard definition of concussion that all sports must use, and a paid medical officer at every major sporting event. But the long-term effects on brain health are not clear, researchers say. And they stress that there are many health benefits to taking part in sport, which must also be taken into account.