Higher levels of the female hormone progesterone appear protective in cases of mild concussion, US researchers have found.
A pilot study at Northwestern University in Illinois has shown that when a female athlete suffers a concussion during the phase of her menstrual cycle when progesterone is highest, she feels less stress. Feeling stressed is one symptom of concussion. Feeling less stressed is a marker of recovery.
The study also revealed that the reason for the neural protection is increased blood flow to the brain as a result of higher progesterone levels.
“Our findings suggest being in the luteal phase (right after ovulation) of the menstrual cycle when progesterone is highest – or being on contraceptives, which artificially increase progesterone – may mean athletes won’t have as severe symptoms when they have a concussion injury,” said co-author Amy Herrold, research assistant professor of psychiatry and behavioral sciences at the university’s Feinberg School of Medicine.
“Resolving those symptoms is especially problematic for our athletes who are trying to return to school, their sports and everyday life after a concussion,” said lead author Jennie Chen, a research assistant and professor of radiology at Feinberg.
The athletes enrolled in the study, the findings of which have been published in the journal Neurotrauma, were involved in a range of sports at a club level, including soccer, ultimate frisbee, triathlon, lacrosse, women’s rugby and tennis. The focus on club athletes is important because more college students take part in club athletics than varsity athletics, Herrold said. In addition, club athletics are not as tightly monitored, possibly leading to increased exposure and under-reporting of concussion.
Northwestern investigators found increased blood flow in the brain when a female athlete had a higher level of progesterone due to her menstrual cycle phase. The region, the middle temporal gyrus, is important for information processing and integrating visual and auditory stimuli. It also has been implicated in social anxiety disorder.
Recovery is stressful for athletes after a concussion or mild traumatic brain injury, particularly if they are pulled from classes for a time and struggle to keep up.
“When they are recovering from a concussion, they get very stressed trying to keep up with course work and making up for lost time,” Herrold said. “Their ratings on perceived stress are really important for their overall recovery from the injury and getting back to normal.”
Big gap in research on female concussion
The bulk of sports-related concussion research has been focused on male athletes. The study fills a big gap in the literature by studying female club athletes, Herrold said.
“The trajectory of recovery from mild traumatic brain injury is different in female athletes than male athletes. Male athletes have a shorter length of recovery than females, despite similar symptom severity.”
For the study, investigators enrolled 30 female collegiate athletes and assessed them three to 10 days after a concussion or mild traumatic brain injury. Assessments included an MRI scan to examine brain blood flow, a blood draw to examine progesterone levels and self-reported symptom questionnaires, including the perceived stress questionnaire.
Once an injured athlete was studied, the investigators enrolled a healthy control athlete who was matched based on age, ethnicity, contraceptive use and type, and menstrual cycle phase.
It may be helpful for clinicians caring for injured women to consider the phase of the athlete’s menstrual cycle and what, if any, hormonal contraceptives they are on, Herrold said. Both will affect progesterone levels and could affect brain blood flow and perceived stress.
“Clinicians also may want to evaluate wider use of hormonal contraceptives that raise progesterone levels for athletes who are at risk for incurring a concussion or mild traumatic brain injury as there could be potential for neuroprotection,” Herrold said.
In future research, Chen and Herrold plan to study if these results can be replicated in a wider sample of female athletes. They also want to compare what they found in males and females competing in sports with concussion risk.