Differences between the male and female brain have been the subject of extensive research for decades. Although difficult to study, research has shown that being XY vs. XX can correlate to differences in how you think, feel and even respond in a given situation.
But did you know that males and females may also differ when it comes to concussion injuries?
Recent research suggests females may be more susceptible to sustaining concussion injuries than males, and may also take longer to recover.
It has been well-established that in sports where both sexes participate and the rules are similar, girls tend to have a higher incidence of concussion than boys. One study found that female high school athletes are 1.56x more likely to sustain a sports-related concussion than their male counterparts playing the equivalent sport (1). A more recent study put it at 2.2x increased incidence of concussions in girls vs. boys playing the same sports (2).
A systematic review by Prien et al. (2018), found that women’s ice hockey ranked third (behind only men’s rugby and men’s football) for the highest concussion rates during game play (3). This was ahead of men’s hockey which is a full contact version of the same game. Another study also found that girl’s soccer had the highest incidence of concussion of all high schools sports (4). Even higher than boys football!
There certainly looks to be a sex difference in regards to susceptibility.
Recently, a large meta-analysis examined sex-differences in the incidence of sports-related concussion(5). Meta-analyses are particularly useful because they combine all previous studies into one – a summary of sorts. This particular meta-analysis examined various ages and sports (contact & non-contact) and found that in both soccer and basketball, there was a significantly higher incidence of concussion in females compared to males. There were no significant differences found between girls and boys with hockey and lacrosse which are both full contact for males, and non-contact for females.
Why the difference with some sports and not with others?
One reason may be the involvement of contact during game play. Soccer and basketball both have similar levels of contact between the sexes and females appear to sustain more concussions. Whereas with hockey and lacrosse, men engage in significantly more contact than women and this may increase the incidence of concussion among the males in these sports. Even still, it only puts them equal to females in terms of concussion risk.
So it seems that girls do get more concussions than boys – but does this mean that girls are more susceptible to concussions?
There are several theories as to why girls may get more concussions than boys but only two of them deal with increased susceptibility. Here are the theories:
Hormonal fluctuations – Hormone fluctuations throughout the menstrual cycle are thought to increase the susceptibility of women to concussions. Progesterone is a potent anti-inflammatory compound. Just prior to menstruation, progesterone levels plummet (this may also trigger PMS symptoms in some). Some of the theories (read: More evidence needed) are that women may be more susceptible to injury around this sudden progesterone drop.
Differences in neck strength – females generally have decreased head-neck strength compared to males and tend to go through greater peak acceleration and increased angular displacement during impact than males. This theoretically makes females more likely to sustain acceleration/deceleration forces required to produce a concussion.
Reporting differences – some researchers suggest that females may simply be “more honest” than males leading to increased relative reporting of these injuries for females in sport. A very recent study has pushed back on this idea however. A survey done by Chizuk et al., 2021 found that females in middle school, high school, and college were just as unlikely as males of the same age to NOT report concussion injuries (6)
In addition to differences in susceptibility, studies also indicate that once concussed, the recovery trajectory may be longer in females than males.
A large Canadian study sought to develop a “clinical prediction rule” that would better help clinicians determine which patients would go on to have prolonged symptoms. This can help clinicians determine who should be given early access to interventions and be monitored more closely. In this study, based on the symptoms and clinical assessments of over 3000 concussed adolescents, risk scores were assigned – the higher the risk score, the higher the likelihood that a particular patient would suffer from persistent symptoms. In this study, the prediction rule found that being male was assigned a score of ZERO (i.e., no added risk) and being female was automatically assigned a score of 2 (7).
Why could this be? Once again, all we have at this point are theories…
Preliminary studies have found that women who sustained concussions in the 2 weeks prior to menstruation (luteal phase) had slower recovery than women who were concussed in the 2 weeks directly after their period or women taking the birth control pill.
Also, females generally have a reduced head to neck ratio compared to males, which may lead to more acceleration, potentially a more severe injury, and therefore longer recovery.
Other theories include women taking more time to present for care (increasing the chance for chronicity) and the tendency for male sports to have more funding and perhaps better sideline medical personnel and post-concussion care. In fact a 2019 study found that girls DID take longer to recover than boys, BUT when the time to clinical presentation was accounted for, there was absolutely no difference in recovery time! (8). In layman’s terms: girls took longer to recover only because it took them longer to see a trained healthcare professional after their injury. When girls were seen in the same time frame after injury as boys, there were no differences in recovery!
Although these theories warrant further investigation, the preliminary findings are interesting nonetheless!
If you’d like to learn more about these interesting sex differences, watch this recent video podcast on the topic:
Bretzin AC, Covassin T, Fox ME, Petit KM, Savage JL, Walker LF, et al. Sex Differences in the Clinical Incidence of Concussions, Missed School Days, and Time Loss in High School Student-Athletes: Part 1. The American Journal of Sports Medicine. 2nd ed. 2018 May 23;46(9):2263–9.
Kerr ZY, Chandran A, Nedimyer AK, Arakkal A, Pierpoint LA, Zuckerman SL. Concussion incidence and trends in 20 high school sports. Pediatrics. 2019 Nov 144(5) e20192180.
Prien A, Grafe A, Rössler R, Junge A, Verhagen E. Epidemiology of Head Injuries Focusing on Concussions in Team Contact Sports: A Systematic Review. Sports Medicine. 2018 Jan 18;48(4):953–69.
Schallmo MS, Weiner JA, Hsu WK. Sport and Sex-Specific Reporting Trends in the Epidemiology of Concussions Sustained by High School Athletes. J Bone Joint Surg Am. 2017 Aug;99(15):1314–20.
Cheng J, Ammerman B, Santiago K, Jivanelli B, Lin E, Casey E, et al. Sex-Based Differences in the Incidence of Sports-Related Concussion: Systematic Review and Meta-analysis. Sports Health: A Multidisciplinary Approach. 2019 Sep 30;53(2):194173811987718–6.
Chizuk HM, Haider MN, Solomito M, Kostyun R, Willer BS, Leddy JJ, Wang D. Concussion reporting behaviors in student athletes across sexes and levels of contact. Journal of Concussion. 2021; 5(1-5)
Zemek R, Barrowman N, Freedman SB et al. Clinical risk score for persistent post-concussion symptoms among children with acute concussion in the ED. JAMA 2016; 315(10):1014-1025.
Desai N, Wiebe DJ, Corwin DJ, Lockyer JE, et al., Factors affecting recovery trajectories in pediatric female concussion. Clin J Sport Med. 2019;29(5):361-367.
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