MONDAY, June 10, 2013 (HealthDay News) -- Kids who suffer a concussion may have a substantially slower recovery if they've sustained one or more blows to the head in the past, a new study finds.
Researchers report that among 280 kids and young adults who sustained a concussion over one year, those who'd suffered one in the past took twice as long to recover -- typically 24 days, versus 12 days for kids with no history of concussion.
What's more, the number of past concussions, and the timeframe of kids' head injuries, appeared key. Young people who'd sustained a concussion in the past year had a prolonged recovery from the current one -- typically 35 days.
Recovery was also slower for those who'd had two or more concussions in the past, at any time. It typically took 28 days for their symptoms to fully resolve.
Experts said the findings, reported online June 10 and in the July print issue of Pediatrics, have implications for managing kids' head injuries.
When they have had multiple concussions, or a relatively recent one, parents and doctors should probably be "extra cautious" about letting them back into sports, said lead researcher Dr. Matthew Eisenberg, of Boston Children's Hospital.
Sports are a major cause of young people's concussions -- and accounted for almost two-thirds of those in this study. In general, experts say those kids should not get back into the game until all of their symptoms have resolved, and a health professional gives them the OK.
So be even more patient when a youngster has a history of concussions, Eisenberg said. That means not only waiting until any symptoms go away to get active again, but gradually moving back into the normal routine.
"You do not want them to go from zero to 60," Eisenberg said.
That gradual return is important any time an athlete has had a concussion. But it's probably even more vital with repeat concussions, agreed Keith Yeates, chief of pediatric psychology and neuropsychology at Nationwide Children's Hospital in Columbus, Ohio.
"It's been part of the medical lore, this idea that multiple concussions are 'bad,' and having a repeat concussion within a short amount of time is bad," Yeates said. But this study, he added, helps confirm that.
One of the big remaining questions, though, is whether kids with repeat concussions suffer any long-term consequences, Yeates said.
"We don't know if there are any effects on long-term cognition or memory," study author Eisenberg agreed. There have been reports that professional athletes who suffer blows to the head may be at heightened risk of degenerative brain diseases later on. A recent study found increased risks of Alzheimer's and Lou Gehrig's disease in retired pro football players, for example.
But Eisenberg pointed out that those athletes are routinely exposed to high-impact collisions. No one knows if kids' concussions, even repeat ones, would translate to health effects down the road.
According the U.S. Centers for Disease Control and Prevention, more than 173,000 U.S. children and teens land in the ER each year because of a concussion sustained in sports or recreational activities, like bike riding.
Concussion symptoms include headache, dizziness, nausea, ringing in the ears, fatigue and confusion -- though these problems may not become noticeable until hours after the jolt to the head. And contrary to popular belief, concussions usually do not involve loss of consciousness.
The current findings are based on 280 11- to 22-year-olds treated at the Boston Children's ER for a concussion. Of these, 21 patients had a concussion within the past year; and typically, Eisenberg's team found, their recovery from the current injury was three times longer, versus the recovery times of kids who'd never had a concussion before.
It's not clear, though, whether that high-risk time window actually lasts a whole year. "We need to figure out, more specifically, what the vulnerable window is," Eisenberg said. "Is it one month? Is it three months? We don't know."
Both Eisenberg and Yeates said they are big supporters of sports and exercise, and they would not want parents to keep their kids out of activities over concussion fears.
But both also said that if your child has suffered more than one concussion in a particular sport, it may be time to think about changing to a different activity.
"We don't know what the long-term risks might be," Yeates said. "But since we don't know, it seems best to be conservative and assume it's not good for kids to have multiple concussions."
The U.S. Centers for Disease Control and Prevention has about concussions and sports.