A Single Concussion May Have Lasting Impact

A single concussion experienced by a child or teenager may have lasting repercussions on mental health and intellectual and physical functioning throughout adulthood, and multiple head injuries increase the risks of later problems, according to one of the largest, most elaborate studies to date of the impacts of head trauma on the young.

You cannot be an athlete, parent of an athlete, sports fan or reader of this newspaper and not be aware that concussions appear to be both more common — and more dangerous — than most of us once thought. According to a report released last week by the health insurer Blue Cross Blue Shield, based on data from medical claims nationwide, the incidence of diagnosed concussions among people under the age of 20 climbed 71 percent between 2010 and 2015. The rates rose most steeply among girls, with the incidence soaring by 119 percent during that time, although almost twice as many concussions over all were diagnosed in boys.

The report acknowledges that the startling increase may partly reflect a growing awareness of the injury among parents, sports officials and physicians, which has led to more diagnoses. But the sheer numbers also suggest that more young people, particularly young athletes, are experiencing head injuries than in the past.

Similar increases have been noted among young people in other nations.

But the consequences, if any, for their health during adulthood have largely remained unknown.

So for the new study, which was funded primarily by the Wellcome Trust and published in August in PLOS Medicine, scientists from Oxford University, Indiana University, the Karolinska Institute in Stockholm and other universities turned to an extensive trove of data about the health of people in Sweden.

A plethora of linked registries in that nation contain information about people’s medical and hospital visits, socioeconomic status, education, physical disabilities and other aspects of their lives, says Dr. Seena Fazel, a professor of forensic psychiatry at Oxford and the new study’s senior author. The registries also allow researchers to compile information about family members.

In this case, the scientists concentrated on all Swedes born between 1973 and 1985 and looked for those who had experienced a head injury of some kind before the age of 25. More than 104,000 people qualified.

The researchers pulled data about these people for 40 years or until someone had either died or emigrated from Sweden.

For each participant, the researchers also compiled comparable medical and other records for a sibling who had never been given a diagnosis of a head injury and compared outcomes both between family members and against the full population of the country.

The results were discomfiting. Young people who had experienced a single diagnosed concussion — which the researchers categorized as a mild traumatic brain injury — were much more likely than the nation’s general population and than their own siblings to be receiving medical disability payments as adults.

They also were significantly more likely to have sought mental health care and much less likely to have graduated from high school or to have attended college than their uninjured brother or sister.

And they were about twice as likely as an uninjured sibling to die prematurely.

The possibility of lingering physical or psychological problems during adulthood rose precipitously, the researchers found, if someone had experienced more than one concussion while young, or if his or her brain injury had been more severe than a concussion.

The outcomes also generally were worse if someone had experienced head trauma after the age of 15, probably because the brain is less resilient than in earlier childhood, Dr. Fazel says. (The researchers did not quantify the causes of the injuries in this study, but past research shows that in the very young, he says, brain injuries usually result from falls, with sports becoming the primary cause in teenagers, and auto accidents the main cause among young adults.)

There was, thankfully, encouraging news squirreled away within the data. While young people who had been hit in the head displayed heightened risks for physical and psychological difficulties as adults, most, in fact, were fine.

“The majority of individuals who had diagnoses of brain injury in our study did not experience adverse outcomes,” Dr. Fazel says.

Unfortunately, it is impossible at the moment to identify which children or teenagers who experience head trauma may be most at risk of struggling in later life and which will instead recover without apparent complications, he says.

So the message of this study further underscores that, whenever possible, we should take steps to prevent childhood head injuries. While “there are lots of benefits from sports,” Dr. Fazel says, it may be important to consider changes to the rules or equipment in contact sports, like football and soccer, to try to reduce head trauma.

If a young person does suffer head trauma, he continues, more and longer-lasting monitoring is also probably a good idea. Such monitoring may be especially important if the child shows any signs of “a decline in psychosocial performance,” he says, such as a drop in grades or a change, even subtle, in personality. A neurologist can provide useful assessments, and regular follow-up neurological assessments may need to be continued, even into adulthood.