Researchers are still perplexed as to the effects of concussions on female athletes. But a Northwestern duo believes accounting for the menstrual cycle could be the key.

By Brittany Callan
Medill Reports

For rugby player Brittany O’Dell, it took a Will Smith movie to scare her into taking sports injuries seriously.

The 2015 true-life film “Concussion” chronicled the discovery of the degenerative brain disease Chronic Traumatic Encephalopathy, or CTE, and starred Smith as Dr. Bennet Omalu, the physician who discovered the condition. O’Dell, who plays for Chicago North Shore Women’s Rugby, says watching the film opened her eyes to the potential long-term effects brain injuries in her sport could have for athletes who didn’t take them seriously. “That made me scared a little bit,” she says. “That made me want to enforce recovery to everyone.”

Despite more awareness of the dangerous effects of concussions, players of contact sports are still returning to field before waiting for their concussions to subside. While research is focusing on the long-term effects of concussions, there is still much that is not understood, especially when it comes to female athletes.

Concussions in females haven’t been studied as often as those in male athletes, according to researcher Amy Herrold, who works in the psychiatry and behavioral sciences department at Northwestern University.

Moreover, current research on concussions is failing to take into account notable differences between male and female brains, Herrold says.

The most obvious difference between female and male athletes? The menstrual cycle.

Recent studies show the menstrual cycle affects brain function and even how the body heals from such common sports injuries as Achilles tendon strain. Researchers are betting there’s a good chance the menstrual cycle affects the way our brains respond to concussion, too.

“There’s some evidence that this is a major gender difference that hasn’t been addressed,” Herrold says.

Herrold and Yu Fen “Jennie” Chen, who is a researcher in Northwestern’s department of radiology, are currently leading a unique study that controls for the phase of the menstrual cycle when study participants undergo an MRI. Their study is part of the larger research efforts of the Concussion Neuroimaging Consortium and is receiving funding from the Eleanor Wood-Prince Grants Initiative.

Herrold and Chen’s study also controls for the types of oral contraceptives players take, as birth control induces a certain phase of the menstrual cycle and creates differences in hormone levels. Their study’s eventual goal is to compare female athletes who participate in collision sports and have suffered a concussion to athletes who participate in non-collision sports.

The study measures participants’ brain activity while the athletes are at rest, which will give an idea of how different regions of the brain are connected to each other and if those connections change following a brain injury. It also will measure cerebral vasculature reactivity (CVR), which is a measure of how blood vessels respond while people hold their breath. Higher levels of CVR are good indicators that the blood vessels in the brain are healthy enough to respond to stress. Chen also plans to explore how white matter, the connective tissue between brain regions, could be affected by concussion.

Currently one of the issues with diagnosing concussions and tracking the recovery process is that the resulting abnormalities in the brain aren’t visible using classic imaging techniques. Because concussions are only mild traumatic brain injuries, easier-to-see brain lesions are not often present.

“That’s where these advanced metrics come into play. It would be really nice to have an objective measure that can be used for diagnosis as well as understanding recovery,” Herrold says.
Herrold and Chen expect work on their study wrap up by year’s end.

Beyond their current research, another promising possibility the duo is exploring is monitoring concussions in the future using eye tracking tests.

“We can use eye movement as kind of a window to the brain to look at measures that may indicate subtle deficits in cognitive and sensory motor function,” Herrold says.

The researchers plan to use eye movement assessments pre-and post-season to compare collision and non-collision athletes to see if there are any cognitive sensorimotor deficits happening from just participation in a season of collision sport. Even athletes who aren’t suffering concussions could still be feeling effects from multiple sub-concussive hits to the head and this could be a way to measure their injury and recovery.

In the meantime, coaches and players are becoming more aware of the importance of fully recovering from a concussion before returning to the game.

When O’Dell had her first concussion in 2009, she had only a team captain and no athletic trainers on the side of the field to discourage her from returning to the game. When she suffered her next concussion in 2011, she had an athletic trainer that required her to get cleared by a neurologist before returning to play, even though her coach would have allowed it. And when she had her most recent concussion this August, her coach didn’t want to let her play until weeks after she was cleared by a doctor.

The experience has made O’Dell more responsive to fellow players who are reeling from concussions, often going out of her way to give them pointers on how to recover.

“I’m trying to be someone to promote taking your brain seriously because you only have one,” O’Dell says.