After a two-year extensive concussion study, the Michigan High School Athletic Association (MHSAA) reported on what they have learned from after having all MHSAA member high schools report suspected concussions and make follow-up reports for each. First and foremost, concussions are of concern beyond football and boys. While football – the highest participation sport in the state– has had the most concussions, the sports that follow are girls basketball (second) and girls soccer (third). Which leads to the second lesson found out in the study: Girls report two to three times as many concussions as boys in basketball and soccer, as well as in softball compared to baseball.
But why? Why do girls have such a high concussion rate considering boys sports have more physical contact, like football? There is the scientific theory that has to do with a female’s susceptibility to a migraine between puberty and menopause. During the child-bearing ages, females undergo considerable hormonal imbalance on a monthly basis in preparation for possible pregnancy. The female hormone Estradiol in particular reaches peak levels as the uterus becomes prepared for possible embryo implantation, and then drops precipitously if no implantation takes place. Estradiol fluctuation is one of the primary culprits in driving migraine. Before puberty and after menopause, males and females suffer with migraine equally. During child-bearing ages, females are about four times more likely to suffer with migraine. As this goes, it may result in a girl’s hit to the head not being as serious looking as boys but may result in more devastating long lasting neurological dysfunction, ranging from visual loss to difficulty speaking to confusion to vertigo to loss of consciousness.
Scientists have also described spreading depression as an acute manifestation of concussion. Following an impact to the brain sufficient to cause a concussion, there are multiple areas of the brain that may develop spreading depression waves, and this may be an important contributing factor to concussion symptomatology. This also explains why concussion symptoms can worsen for hours following the inciting event. For female athletes during their child bearing years, there is a statistically increased likelihood that a female with migraine susceptibility will become concussed, and such females have a lower threshold to developing secondary spreading depression. In other words, females with migraine susceptibility are more vulnerable to developing worsened symptoms relative to their non-migraine counterpart. At present, the spreading depression hypothesis needs further scientific study; however, it is an intriguing explanation of male-female differences. Spreading depression may help to explain studies that demonstrate the following:
- Female concussed athletes report more concussion symptoms than their male counterparts, including poor concentration, lightheadedness, increased fatigue, headache, and visual hallucinations such as seeing stars.
- Female concussed athletes suffer with greater cognitive decline and slowed reaction time relative to males.
- College female concussed athletes perform more poorly on BESS (Balance Error Scoring System) following concussion relative to males.
In addition to suffering with more concussion symptomatology, females have a higher rate of concussion compared to males when playing the following sports:
- Soccer (2.1 x greater risk)
- Softball versus baseball (up to 3.2 x greater risk)
- Basketball (up to 1.7 x greater risk)
Studies have also demonstrated that females have more injuries due to player-surface contact and player-player equipment compared to males (males have more injuries from player-player contact compared to females). Females also may have a higher proportion of recurrent concussions compared to males. There may be factors beyond brain physiology that help explain these differences. One aspect of concussion is the biomechanical readiness of protecting the head from sudden acceleration-deceleration and rotational forces. From this framework, females may be at a disadvantage because they usually have less neck strength than males. This can translate into less ability to counteract mechanical forces that can cause head and neck acceleration-deceleration and rotation. Consider the following statistically significant difference in females compared to males when measuring head-neck strength components and concomitant acceleration forces:
- Females have 25 percent less head-neck segment mass than males.
- Females have 5 percent less head-neck segment length than males.
- Females have 12 percent less neck girth than males.
- Females have 50 percent less isometric neck flexor strength than males.
- Females have 53 percent less isometric neck extensor strength than males.
- Females have up to 44 percent greater head acceleration than males following contact, and have 10 percent greater head accelerations than males during non-contact.
Although there have been major positive changes in equipment and protection for athletes in sports, there needs to be more exploration done with female-male concussion differences. But in the meantime, we all need to spread the word: yes, female athletes also suffer with concussion, and they may be uniquely predisposed to this neurological event.