Brandi Chastain, who scored the last goal in a shoot-out in the finals of the 1999 Women's World Cup, has pledged to donate her brain to concussion research. (Hector Mata/AFP)

Hoping to broaden the attention and research surrounding concussions and chronic traumatic encephalopathy, particularly with regards to women, former soccer star Brandi Chastain pledged to donate her brain posthumously to researchers studying the impact wrought by repetitive head injuries.

“It’s not just football that’s at stake,” Chastain said. “We have millions and millions of young people participating in soccer, and I’m not sure there’s enough advocacy for them. I was compelled to do something.”

Chastain, 47, played parts of 12 years for the U.S. national team, helping the Americans win a pair of Olympic gold medals and two World Cup titles. She more recently has become an outspoken advocate for making soccer a safer sport, urging youth leagues to ban heading the ball by athletes under age 14.

Chastain’s brain one day will go to the brain bank run in partnership by the Concussion Legacy Foundation, the U.S. Department of Veterans Affairs and the Boston University School of Medicine.

“Everybody talks about 1999 and the legacy of that team,” Chastain said. “We won a World Cup, got a lot of attention, but I really think this is another way to make a lasting change and have an impact that lives well past the time that I’m here.”

[Steinberg: Concussions kept her off the court; now she wants to help other deal with them]

Concussion research is a fledging field of study, in large part because of the huge spotlight trained on the NFL and the myriad maladies suffered by some former football players. But much of the emerging science and data have focused on men, revealing little about the impact brain trauma has on women.

"We currently know so little about how gender influences outcome after trauma,” said neuropathologist Ann McKee, director of Boston University’s CTE Center. “Her pledge marks an important step to expand our knowledge in this critical area.”

The Concussion Legacy Foundation has acquired 307 brains, two-thirds of which came from former football players. Just four belonged to women. McKee and her colleagues have been at the forefront of CTE research, identifying nearly 200 cases of the degenerative disease, mostly in former football players. They have yet to identify CTE in a female athlete.

McKee says the absence of case studies doesn’t mean women aren’t susceptible; research simply doesn’t exist for anyone to fully understand the impact concussions have on women. In medical literature, researchers have identified two known cases of CTE in women, one involving domestic violence and the other a young woman with autism who repeatedly banged her head.

“There is great concern that the female brain may, in fact, be more prone to injury and adverse long-term outcome than the male brain . . . but the rate of brain donation from women has been exceedingly low,” McKee said.

She pointed to some studies that have shown women have a longer rate of recovery and more persistent post-concussion symptoms than men. Much of these differences were discussed last weekend in Washington at a first-of-its-kind summit focused solely on concussions in women, an all-day conference co-sponsored by the nonprofit advocacy group Pink Concussions and Georgetown University Medical Center. The event brought together medical experts to examine the issue in sports, military, domestic situations and beyond.

“Who’s talking about females?” Brian Hainline, the NCAA’s chief medical officer, asked at one point. “Why are we focused so much on men’s football? . . . We need to talk about women.”

[NFL data shows huge surge in reported concussions in 2015]

Injury data for both college and high school athletics has found that women suffer more concussions than men who compete in similar sports. Softball players, for example, suffer concussions at twice the rate of baseball players. Women’s soccer, basketball and lacrosse also show similar findings.

The reasons are mostly anecdotal, and research doesn’t yet exist to fully explain how the genders experience concussions differently. Some research has pointed to neck strength, different blood flow in the brain and hormonal differences that could impact both susceptibility and recovery.

“Women are underrepresented in the research,” said Katherine Snedaker, executive director of Pink Concussions. “If you don’t have females in your study [or] you aren’t using female rats, it’s a study where the results only apply to males. The male and female brains are different in so many ways.”

Snedaker said she has suffered more than 20 concussions and four years ago made a pledge similar to Chastain’s. She carries a letter in her purse at all times with instructions to save her brain in case of an accident. Chastain will receive something similar in the coming days, likely in the form of a wallet-sized card, said Chris Nowinski, executive director of the Concussion Legacy Foundation.

Nowinski said finding former female athletes such as Chastain to pledge their brains has been no simple task. While football provides a large population from which to draw, there’s no equivalent on the women’s side.

“Women don’t play football. They aren’t exposed to the sport with potentially the most brain trauma,” he said. “And then remember that Title IX only happened [43] years ago. So we don’t have former professional female athletes who are now in their 70s and who’d be showing these symptoms.”

“So we’re excited to have someone like Brandi pledge her brain because it might be her generation that helps us truly understand the impact concussions have on the female brain.”

Many athletes similarly have pledged their brains, but Chastain is among the most notable women, joining former U.S. Olympic swimmer Jenny Thompson and former soccer star Cindy Parlow Cone, who retired from the sport in 2006 because of concussions after competing on teams that won two Olympic gold medals and the 1999 World Cup title.