A study of former professional football players found that those who participated in tackle football from before the age of 12 were more likely to have memory and thinking problems in adulthood.
The study, conducted by the American Academy of Neurology and published in the journal Neurology, tested 42 former NFL players with an average age of 52 who had been experiencing memory and thinking problems for at least six months.
Half of the players tested began playing tackle football before the age of 12, while the others had not, and both groups had sustained a similar amount of concussions, according to a news release. The study found those who played before age 12 performed significantly worse on all test measures, even after researchers took into account the total numbers of years spent playing football.
According to the news release, those who played football before age 12 performed approximately 20 percent worse in several tests. The players recalled fewer words from a list they had learned 15 minutes earlier and made more repetitive errors on a test of mental flexibility compared to the other group. However, study authors also found that both groups were performing below average on several tests.
"Our study suggests that there may be a critical window of brain development during which repeated head impacts can lead to thinking and memory difficulties later in life," study author Robert Stern said, according to the news release. "If larger studies can confirm this association, there may be a need to consider safety changes in youth sports," he said.
Stern noted that because all of the study's participants were former NFL players, the results may not apply to the general public, or those who did not reach the professional level of playing. Stern recommends more research be done on a broader level before considering policy changes, according to the news release.
"While the researchers did take into account the total years of football played, they were unable to assess the total number of head impacts," Christopher Filley of the University of Colorado School of Medicine said in an accompanying editorial.
"So it's possible that the number of impacts is responsible for the reported results rather than the early age of exposure to football," he said.
Still, Filley said that due to the popularity of the sport with young children in the U.S., it is important to continue conducting studies like this.
"Given that 70 percent of all football players in the United States are under the age of 14, and every child ages nine to 12 can be exposed to 240 head impacts during a single football season, a better understanding of how these impacts may affect children's brains is urgently needed," Filley said, according to the news release.