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Gender Differences In Concussion Severity And Outcomes May Depend On Female's Menstrual Cycle

Hormonal birth control: protective effect? 

The team suspected that women taking birth control pills, which contain synthetic hormones that mimic the action of progesterone, would have similar outcomes to women injured in the low progesterone phase of their cycle. As expected, there was no clear difference between these groups, as women taking birth control pills have a constant stream of sex hormones and don't experience a drop following a head hit, so long as they continue to take the pill.

"Women who are very athletic get several benefits from the pill; it protects their bones and keeps their periods predictable," noted Kathleen M. Hoeger, MD, MPH, a study co-author and professor of Obstetrics and Gynecology at the University of Rochester School of Medicine and Dentistry.

"If larger studies confirm our data, this could be one more way in which the pill is helpful in athletic women, especially women who participate in sports like soccer that present lots of opportunities for head injuries," says Hoeger.

Study limitations

While saying that their study had many strengths, the authors admitted that it also had limitations.

In particular, the differences may have been a result of symptom changes throughout the menstrual cycle, independent of any mTBI, they said. Because women in the premenstrual phase of their cycle at time of injury were likely to again be in that phase 30 days later at follow-up, the difference in outcomes may have been result of predictable differences in self-reported symptoms throughout the menstrual cycle, regardless of overall recovery. But, Bazarian noted, this question was specifically explored in a 2009 study,[2] which found no variation on measures of neurocognition, balance and post-concussive symptoms over menstrual cycle.

Commenting on the study for MomsTEAM, R. Dawn Comstock, PhD, Associate Professor of Epidemiology at the Colorado School of Public Health, and a leading epidemiologist in the study of concussions and other injuries in high school sports, noted that the study involved a "pretty small sample size of the subcategories of interest."

Moreover, Comstock viewed the strength of the relationship between menstrual cycle and outcomes as "only borderline significant" for the cycle issues, and noted what she characterized as "much stronger" correlations between outcomes and concussion history and other injury.

"So, the questions are - will this finding be replicated in other studies in broader/larger/different populations and, if so, what does it really mean?"

Covassin agreed that more research was needed to explain the differences between male and female concussed athletes, as the current study looked at women visiting hospital emergency departments, so that "their mTBI could have been a more severe brain injury than we are used to with a sports-related concussion," and involved a much wider age range (16 to 60) than studies of high school kids.

Gender: a factor in concussion management?

The question of whether gender is a risk factor for concussion and affects females differently is one that has vexed researchers for years.

Although media coverage tends to focus on concussions in male professional athletes, studies suggest that females have a higher incidence of head injuries than men playing sports with similar rules, such as ice hockey, soccer and basketball, experience more severe symptoms, and are more cognitively impaired after injury.

The studies seem to confirm what women and their physicians anecdotally have known for years: Women experience greater cognitive decline, poorer reaction times, more headaches, extended periods of depression, longer hospital stays and delayed return-to-work compared to men following head injury. Such results are particularly pronounced in women of childbearing age; girls who have not started menstruating and post-menopausal women have outcomes similar to men.

The Consensus Statement on Concussion in Sport issued in March 2013 by the 4th International Conference on Concussion in Sport [3] "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 enough."

The new study appears to provide "added weight," says Bazarian, to the body of evidence that female athletes respond differently to concussion than men, a view consistent with his experience as a clinician, in which 70 percent of the patients he treats in the URMC Sport Concussion Clinic are young women; a number he believes is so high because they often need more follow-up care after concussion.

The study also comes on the heels of Covassin's new study[4] finding "partial support" for sex differences in male and female concussed high school soccer players, specifically, that female concussed soccer athletes scored lower on neurocognitive tests of visual memory compared with male concussed soccer athletes at 8 days after concussion, and had a significantly greater number of total postconcussion symptoms than male concussed athletes.

"I think [the 4th Consensus Statement] was correct in sitting on the fence for concussion management," said Covassin. "The research does suggest that females are at greater risk for concussion, but we need more research to determine if we need to make changes in managing a concussion. But maybe by [the time of the 5th Consensus Statement in] 2016, we will have the answer to that question." 

Bazarian agrees. "Now that gender differences in outcomes after TBI have been repeatedly recognized, research should continue to explore why those differences occur" in order to shed light "on the causes of disability after injury and improve patient care and outcomes," his study concludes.



Material from University of Rochester Medical Center.  Press Release: "Menstrual Cycle Influences Concussion Outcomes Study May Reconcile Recovery Differences in Male, Female Gender" (http://www.urmc.rochester.edu/news/story/index.cfm?id=3965)(November 13, 2013) was used in this article.


1. Wunderle K, Hoeger KM, Wasserman E, Bazarian JJ.  Menstrual Phase as Predictor of Outcome After Mild Traumatic Brain Injury in Women.  J Head Trauma Rehabil. 2013 (epub November 13, 2013). 

2.  Mihalik JP, Ondrak KS, Guskiewicz KM, McMurray RG. The effect of menstrual cycle phase on clinical measures of concussion in healthy college-aged females.  J Sci Med Sport. 2009;12(3):383-387.

3. 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.

4.  Covassin T, Elbin RJ, Bleecker A, Lipchik A, Kontos AP. Are There Differences in Neurocognitive Function and Symptoms Between Male and Female Soccer Players After Concussions? Am J Sports Med. 2013;20(10). DOI:10.1177/0363546513509962.

Posted November 22, 2013