Sports injuries are not uncommon, especially in contact games where players routinely collide or have to kick, catch or hit a ball. Concussions are well documented in the NFL and college football, but an overlooked area of head injury and concussion is at the high school level. New research is shedding light on the particular vulnerability of women and girls to a concussion.
A study by researchers at the Penn Center for Brain Injury and Repair looked at brain structure and size to understand why women can have more serious health issues from concussions.
Douglas H. Smith, MD is the director of the Center and a professor of neurosurgery at the Perelman School of Medicine. Using cells from lab rats as well as humans, Smith and his team identified differences in the size of axons, the spindly protrusions from nerve cells that send messages. Women have smaller axons, and within them, there are fewer microtubules. The microtubules are like "train tracks" that shuttle molecules back and forth. They can break when there is an impact to the head, and it's this breakage that causes symptoms like dizziness or blacking out.
In the study, the researchers were able to simulate the force of the average injury received in sports like soccer and saw the mechanics of what happens to these tiny structures in a traumatic brain injury. In a blow to the head, the axons are stretched at a high rate of speed because the blow is so sudden. They are linked throughout the brain, so the entire network takes the hit. The axons usually do not come apart, but the microtubules can split or rupture. Tau proteins, which are related to memory and cognition, are also linked together in the brain, and this rupture throws the balance of molecules in the brain's communication system out of whack. Previous studies have shown that women have worse outcomes after a concussion than men, and this research shows the underpinnings of how that happens.
Dr. Smith explained, "The paper shows us that there is a fundamental, anatomical difference between male and female axons. In the male axon, there are a great number of microtubules, which make the entire structure stronger, whereas in female axons, it's more of a leaner type of architecture, so it's not as strong. You can imagine that if something goes wrong with that transport system, the cargos get dumped out and start to pile up and that will create a huge problem."
Part of the disruption of a head injury and resulting damage is that there are abnormal amounts of calcium and sodium. This shuts down the brain's ability to transmit messages across the network and can also set in motion a process that can cause significant degradation of the nerve fibers. When this damage happens, the results are the behavioral changes seen in patients who have been injured.
Post-concussion syndrome is a serious health problem and can be debilitating. Women typically struggle longer with it than men and have more lingering symptoms. Moving forward the team hopes to look for blood biomarkers. Since the axonal structure is different, the hypothesis is that women might have more axon proteins in the blood after an injury than men have. The possibility of using high-resolution neuroimaging in men and women who play the same sport, such as soccer, might be another way to validate the study and learn more.
Protecting athletes from injuries that often result in long-term health issues is a crucial part of keeping players healthy. In the video below, it's pointed out that high school girls who play soccer players are injured more often than other athletes, so understanding the anatomical differences is a good start to finding effective treatments.