(MENAFN - AFP) Any athlete suspected of getting a concussion during sports should stop play, leave the game and not return until cleared by a licensed healthcare professional, according to new US guidelines out Monday.The risk of concussion is greatest in American football and rugby, followed by hockey and soccer among male athletes, said the new standards by the American Academy of Neurology. In women, the risks are greatest in soccer and basketball.There is no set amount of time that is safe to wait before returning, according to the AAN. Each instance of head injury must be evaluated individually by an expert."If in doubt, sit it out," said Jeffrey Kutcher, a doctor with the University of Michigan Medical School and a member of the AAN.The suggested rules apply to both youth and professional sports, but urge that young people be managed more conservatively because studies have shown they take longer to recover than college age athletes.Past history of head injuries should also be taken into account while evaluating an athlete, said the AAN, which includes more than 25,000 neurologists and neuroscience professionals.The guidelines tighten the group's 1997 standards, which allowed for athletes to return to play after minor head injuries.The AAN said in its 1997 release that athletes suffering these Grade One injuries commonly described themselves as having been "dinged" or having had their "bell rung," when consciousness was not lost and symptoms went away in under 15 minutes."Among the most important recommendations the academy is making is that any athlete suspected of experiencing a concussion immediately be removed from play," said co-lead guideline author Christopher Giza of the University of California, Los Angeles."We've moved away from the concussion grading systems we first established in 1997 and are now recommending concussion and return to play be assessed in each athlete individually," he said in a statement."There is no set timeline for safe return to play."Between 1.6 million and 3.8 million US athletes sustain a concussion each year, "many of whom do not obtain immediate medical attention," said the AAN guidelines, based on a review of scientific literature from 1955 to 2012.Meanwhile, concerns are mounting over the long-term effects of repeated mild traumatic brain injuries, and have led to some uncertainty in how to treat athletes suspected of hurting themselves, the AAN said.Last year, former National Football League star linebacker Junior Seau, 43, shot and killed himself. Subsequent tests showed he had chronic traumatic encephalopathy due to repeated blows to the head taken during his career.His family this year filed a wrongful death lawsuit against the US National Football League for not doing more to protect players from head injuries.The NFL in 2009 implemented stricter guidelines regarding when an athlete can return to play, but their use was not mandated until 2012, noted an editorial in the AAN's journal.According to neurologist David Dodick of the Mayo Clinic, some of the AAN's recommendations are already being followed in professional and collegiate sports, some of which bar an athlete from returning to play in the same game after a suspected concussion."Guidelines such as these are meant to provide state-of-the-art evidence-based guidelines that standardize the approach to concussion," Dodick told AFP.