Whether there are gender differences in the response of athletes to concussive injury has been an active area of research in recent years, but one which "remains somewhat murky, with general trends but few definitive answers." 8
The evidence so far appears to suggest that girls suffer concussions at a higher rate than boys in similar sports:
- A 2007 study 1 found that the concussion rate for girls was 68 percent higher than boys;
- A 2011 study2 found that the concussion rate for girls in high school soccer (0.35 per 1000 participations by an athlete in a practice or competition or athlete-exposures (AEs) was double that of boys (.017 per 1000 AEs);
- The 2007 study found the concussion rates in high school basketball were almost 3 times higher for girls than boys.1
- The 2011 study reported that the concussion rate for girls was 1.7 times higher than for boys.
Gender differences in concussion severity?
Whether girls more symptoms at baseline and post-concussion, have better verbal memory scores but poorer visual memory scores at baseline, and experience greater levels of acute, postconcussive neurocognitive impairment remains unclear.
A number of recent studies have reported that female athletes - high school and college - report more post-injury symptoms after concussion.3,4,5 and also perform worse than male athletes on post-concussion tests of visual memory.4,7
A 2007 study1 found longer recovery times, while a 2009 study3 found that girls with a previous history of concussions reported more and different concussion symptoms (particularly headache), although admitting to the possibility that male and female athletes may report symptoms differently due to psychological or personality factors not directly related to concussion.
The 2011 study,2 found no difference in the number of symptoms reported between male and female athletes, no difference in the time symptoms took to resolve (most reported resolution of their symptoms within 3 days of injury) or in the time it took for girls and boys to return to play (median time for RTP was 3 to 6 days). The one difference: girls reported symptoms more subtle and easily missed or attributed to causes other than concussion than those of boys.
In the 2012 study,8 researchers at Vanderbilt University Medical Center and the Vanderbilt Sports Concussion Center studied tightly matched, homogeneous groups of 40 male and 40 female concussed soccer players. They found no gender differences in symptoms at baseline (pre-concussion) or in the first week after concussion, and were unable to replicate the findings of previous studies of mixed groups of athletes from a variety of sports which had reported small but significant gender differences, both at baseline in terms of symptoms and neurocognitive test scores (girls reported more headaches, fatigue, sleep difficulties, irritability, sadness, nervousness, feeling more emotional, feeling slowed down, and difficulty concentrating9 and on verbal memory tasks, while males perform better on tests of visual memory7,11) and post-concussion, with girls reporting a higher number of symptoms3,10 and performing more poorly on neurocognitive testing (significantly slower reaction times).3,5 The only significant gender-related difference identified by the Vanderbilt researchers was that female high school soccer players reported a greater number of post-concussion symptoms.
The findings "re-emphasizes the fact that concussions aren't just a concern for high school football players; they can happen to athletes playing all types of sports," said Dawn Comstock,Ph.D., co-author of the 2007 study and associate professor in the Department of Epidemiology at the Colorado School of Public Health.
"Generally speaking, the medical profession does not do a very good job in recognizing that female athletes sustain concussions at an equal or even higher rate as males," said MomsTeam.com concussion expert emeritus, Dr. Robert Cantu of Brigham and Women’s Hospital and the Sports Legacy Institute in an interview with the New York Times. "It’s flying under the radar. And, as a result, looking for concussions in women is not pursued with the same diligence, and it’s setting girls up for a worse result."
The reasons concussion rates are consistently higher for girls than boys in same sports are unclear.
One reason may be anatomical: girls may be at higher risk prone to concussions because their heads are smaller (one study of collegiate soccer players found that females had 26% less total mass in their head and neck than males)14 and/or because their neck muscles are less developed than boys" and not as good as boys at absorbing shock of impact.
The second possible reason for the higher concussion rate in girls may be cultural.
- Girls get more attention? The 2007 study's authors surmise that athletic trainers may pay more attention to girls’ injuries than boys because “society has tended to be more protective of female athletes." "As a society, we protect girls more than boys. Boys have to be tough and learn to play through pain, so they will be less likely to report a concussion,” says Comstock. Coaches, athletic trainers and parents tend to be more cautious about letting girls return to play than boys. “Coaches and parents may be more sensitive to injury to the female head,” says Christopher Ingersoll, the journal’s editor-in-chief and a professor of sports medicine at the University of Virginia.
- Girls more likely to self-report? Girls may self-report at higher rate than boys15 (but, like boys, probably under-report, either because they don't want to lose their spot on the team or out of ignorance of risk). "Women may just be a bit more honest than men in terms of honestly admitting that they've had post-concussion symptoms,” suggests Dr. Cantu, a sentiment echoed by Ingersoll, who speculates that, “Culturally, it may be OK for girls to talk about a concussion. Athletes who play tough, macho sports may not be as open” to talking about them. A 2012 study in the American Journal of Sports Medicine4 reported on research from 2002 suggesting that "male athletes play though pain and try to hide and minimize their symptoms in an effort to avoid removal from sport, whereas female athletes tend to be more concerned about their future health." In his 2012 book, Concussions and Our Kids,16 Dr. Cantu speculates that the concussion rate for boys and girls may actually be the same but has been skewed in the studies by the fact that boys under-report concussions more than girls. He wonders just "how different would the picture be if all concussions were counted, not just those that youth athletes report to coaches and trainers?" Some strongly dispute this theory. As high school soccer coach, Gary Lynch, told the Baltimore Sun: "These kids are players. If you get to [be one of] the top soccerplayers, if you think they want to come out of the game, they're like the boys. You've got to tell them they have a concussion. They are not going to come over and tell you... It doesn't work that way. It sounds like an easy excuse, an easy reason to make up why there's more girls than boys, and I don't buy it."
- Hormones/metabolism/cerebral blood flow.15 Animal studies have suggested that estrogen and progresterone may act to protect the brain after more severe traumatic brain injury (tBI), but a study of rats found that estrogen actually made tBI worse in female rats but served as a protective factor in male rats. Several researchers have suggested that women may have a greater rate of cerebral blood flow and an increased demand for glucose, with one study suggesting that, as a result, a concussion may exacerbate the neurometabolic cascade13 after injury, resulting in further decreases in cerebral blood flow and increases in glycemic demands, which may lead concussed female athletes to exhibit prolonged neurocognitive impairments compared with male athletes.
- Differences in training. Some suggest that, girls aren't as accustomed as boys getting hit, citing, for example, the fact that in ice hockey, boys are allowed to body check after a certain age (currently age 12 or Bantam), while body checking in girl's hockey isn't allowed at any age, while no checking is allowed in girl's lacrosse but is, of course, allowed in boy's. So, the argument goes, girls aren't as prepared to handle contact.
Education & proper management needed
Regardless of the reason, Comstock hopes coaches, athletic trainers, and parents will treat head injuries in female athletes more seriously or to delay their return to play.
Parents and coaches and primary physicians should all know the definitions of concussion, the signs of continued post-concussion syndrome, the guidelines for return to normal activity and the signs that should keep an athlete out of play for an entire season or longer," advises Dr. Jean Ogborn, a pediatric emergency medicine specialist at Johns Hopkins Children's Center, in an interview with ABC News.
"What is very important about this  article is that it points out that concussions can occur in girls' sports with significant frequency, and that girls and their parents need to be aware that these injuries must be carefully managed to prevent permanent damage," Ogborn says.
A factor in concussion management?
The Consensus Statement on Concussion in Sport issued by the 4th International Conference on Concussion in Sport12 held in Zurich in November 2008 "accepted that gender may be a risk factor for injury and/or influence injury severity" but did not list female gender as a possible modifier in the management of concussions because there was no "unanimous agreement that the current published research evidence is conclusive."
The 2012 study in the American Journal of Sports Medicine,4 however, recommended that gender be considered by clinicians when interpreting the results of symptom reports, neurocognitive testing, and postural instability assessments (e.g. BESS) following concussion.
The authors of the 2012 Vanderbilt study8 cautioned against interpreting their results as indicating that there is no gender-based difference in acute response (symptoms or neurocognitive scores) to concussive injury in high school athletes, or that gender should always be considered a modifying factor in managing a concussion. Instead, they were supported the interim position taken by the Zurich consensus statement:12 that gender may be a risk factor for injury and/or influence injury severity.
1. Gessel LM. Fields SK. Collins CL. Dick RW. Comstock RD. Concussions among United States high school and collegiate athletes. J. Athl Train. 2007; 42(4): 495-503.
2. Frommer L, Gurka K, Cross K, Ingersoll C, Comstock R.D., Saliba S. Sex Differences in Concussion Symptoms of High School Athletes. J. Ath. Train, 2011; 46(1):000-000.
3. Colvin AC, Mullen J, Lovell MR, West RV, Collins MW, Groh M. The Role of Concussion History and Gender in Recovery from Soccer-Related Concussion. Am. J. Sports Med. 2009; 37(9): 1699-1704.
4. Covassin T, Elbin R, Harris W, Parker T, Kontos A. The Role of Age and Sex in Symptoms, Neurocognitive Performance, and Postural Stability in Athletes After Concussion. Am. J. Sports Med. 2012;20(10); published on April 26, 2012 at doi:10.117703654651244454
5. Broshek D et. al. Sex differences in outcome following sports-related concussion. J Neurosurg. 2005;102(5):856-863.
7. Covassin T, Schatz P, Swanik C. Sex differences in neuropsychological function and post-concussion symptoms of concussed collegiate athletes. Neurosurgery 2007:61:345-351.
8. Zuckerman SL, Solomon GS, Forbes JA, Haase RF, Sills AK, Lovell MR. Response to acute concussive injury in soccer players: is gender a modifying factor? J Neurosurg: Pediatrics 2012; DOI:10.3171/2012.8.PEDS12139 (published online ahead of print October 2, 2012)(accessed October 15, 2012).
9. Covassin T, Swanik CB, Sachs M, Kendrick Z, Schatz P, Zillmer E, et. al. Sex differences in basesline neuropsychological function and concussion symptoms of concussed collegiate athletes. Br J Sports Med 2006;40:923-927.
10. Broshek DK, Kaushik T, Freeman JR, Erlanger D, Webbe F, Barth JT. Sex differences in outcome follwoing sports-related concussion. J Neurosurg 2005;102:856-863.
11. Weiss E, Kemmler G, Deisenhammer E, Fleischhacker W, Delazer M. Sex differences in cognitive functions. Pers Individ Dif 2003;35:863-875.
12. McCrory P, et al. Consensus statement on concussion in sport: the 4th International Conference on Concussion in Sport held in Zurich, November 2012. Br J Sports Med 2013; 47:250-258.
14. Tierney R, Sitler M, Swanik C, et al. Gender differences in head-neck segment dynamic stabilization during head acceleration. Med Sci Sports Exerc 2005;37:272-279.
15. Makdissi M, Davis G, Jordan B, Patricios J, Purcell L, Putakian M. Revisiting the modifiers: how should the evaluation and management of acute concussions differ in specific groups? Br J Sports Med 2013;47:314-320.
16. Cantu R, Hyman M. Concussion and Our Kids (Houghton Mifflin Harcourt 2012)
Updated and revised May 5, 2013