If your child has ever taken a knock to the head on the playing field, a new study has some reassuring news: There's no evidence that a concussion shaves points from a kid's IQ.

Researchers found that compared with children and teens who'd suffered broken bones or sprained ankles, those with a recent concussion did just as well on IQ tests up to three months after the head injury.

The study — published July 17 in Pediatrics — should ease the worries of many parents, as well as young people who've taken a knock to the head in sports, play or accidents.

They often ask whether the injury will dull their mental sharpness, noted lead researcher Ashley Ware, an assistant professor of psychology at Georgia State University.

"This study is good news," she said.

Concussions are a type of traumatic brain injury, occurring when the brain gets jostled around in the skull. That can cause various immediate symptoms, such as headache, confusion, dizziness and a general sense of feeling unwell.

It's well known that more severe brain trauma can harm kids' long-term intellectual functioning, but studies have come to mixed conclusions when it comes to concussions.

Those studies, however, have been hampered by various shortcomings, Ware said. Many have been small, or compared concussed kids with peers who were perfectly healthy.

That's an issue because kids who sustain a concussion may be different from their peers in various ways — possibly more impulsive, or more likely to have attention problems, for instance. Plus, they have gone through the stress of being injured and taken out of their usual activities.

"It's important to compare kids with concussion against a group of similar kids," said Talin Babikian, a clinical neuropsychologist at the University of California, Los Angeles David Geffen School of Medicine.

That's a strength of the latest study, according to Babikian, who wrote a commentary published with the findings.

She said that health care providers experienced in managing concussion already know, through that experience, that most kids with a single, uncomplicated concussion do fine.

The problem comes, Babikian said, when a teenager with a concussion is sitting at home Googling and comes across a single study that suggests all will not be fine. That may trigger anxiety and something of a self-fulfilling prophecy.

Like Ware, Babikian hoped the new findings help put some minds at ease.

The study involved 866 kids, ages 8 to 17, who were seen in the emergency room at any of seven hospitals in the United States and Canada. Overall, 566 had sustained a concussion, and 300 were treated for an orthopedic injury (mainly fractures or joint sprains).

All of the kids returned to take standard IQ tests, either three to 18 days after the injury, or three months later.

Overall, Ware's team found, kids with concussion had similar IQ scores to those with orthopedic injuries, at both time points. The average scores, in overall IQ and subtests of vocabulary and reasoning, were "well within" the normal range in both injury groups.

Even when kids had a history of previous concussion, or had more severe symptoms, that did not seem to harm their IQ test performance, the study found.

"The good news is, it's highly unlikely there will be long-term cognitive problems when a concussion is managed appropriately," Babikian said.

That management, she noted, is different today from even just 10 years ago. Doctors once commonly advised against physical or mental activity until a kid's concussion symptoms had passed.

"But now we know that going back to normal life is part of getting better," Babikian said.

In general, she said, kids with a straightforward concussion should take it easy for a day or two, then gradually get back into their routine. While they should not jump back into sports or activities that could cause a repeat head injury, light exercise -- like taking the dog for a walk — is a good thing, Babikian said.

Getting back to a normal schedule also helps avoid sleep disruptions, Babikian noted. That's key because good sleep is a "major piece of the puzzle in recovery," she said.

It's true that some kids have symptoms that linger for weeks to months after a concussion -- such as headaches, concentration problems or depression symptoms.

But often, Babikian said, such lasting problems are not a result of the concussion itself. Mood symptoms, for example, can stem from disruptions to a child's daily life, or the trauma of the incident that caused the head injury.

It's important any lingering symptoms be addressed, Babikian said, but they should not automatically be attributed to the concussion.