When it comes to youth sports, concussions aren't confined to the football field.
Soccer players – especially girls – also experience the dizziness, nausea, blurry vision and headaches that can accompany head trauma.
The American Journal of Sports Medicine studied the rate of concussions in high school athletics from 2008 through 2010.
Of the 1,936 reported concussions during the study, 47 percent were suffered playing or practicing football. No. 2 on the list: girls’ soccer, at 8.2 percent.
A 2013 report from the American Academy of Neurology found that football has the highest rate of concussions in high school sports (1.55 per 1,000 games), with girls soccer placing second (0.97 per 1,000 games). 
Doctors and coaches cite multiple factors for the high number of brain injuries in girls’ soccer. Among them:
• Girls’ necks and heads are smaller than their male counterparts, giving their brains less protection. Men tend to have stronger necks, and a stronger neck can help reduce the risk of a concussion by slowing down the moving of your head.
• Inspired by iconic heroes like Mia Hamm, Brandi Chastain and Abby Wambach — plus lured by potential college scholarships — girls are playing more aggressively, sometimes recklessly so.
• When in midair, boys appear to have better spatial awareness, recognizing potential collisions and avoiding them.
• Girls may be more inclined to report concussions than boys.
“None of (these factors) are conclusive,” said Dr. William Perry, the associate director of neuropsychiatry and behavioral medicine at UC San Diego Health System. “While it’s a hypothesis, we just don’t know for sure.”
Interestingly, the physical act of heading a soccer ball is not believed to be one of the major reasons for head trauma.
Said Perry: “Essentially, there is no data supporting heading the ball causing concussions.”
But new research has shown that players who hit the ball with their heads often have brain abnormalities similar to people who are known to have had concussions.
Dr. Michael Lipton, a neuroradiologist at the Albert Einstein College of Medicine in New York City and lead author of the study suggests that while a definitive cause and effect relationship between heading the ball and brain injury cannot be inferred, soccer should start keeping a “head count” to monitor the number of headers players use in a given game. The head count would be analogous to the “pitch count” in baseball that ensures pitchers don’t throw too many pitches in a single outing. 
The study authors pointed out that soccer players head the ball six to 12 times each game, and the ball can travel more than 50 mph each time. During practice, players can expect to hit the ball with their head 30 or more times. While one header probably won't result in any traumatic brain damage, researchers worried that repeatedly hitting the ball would have lasting effects.
"Repetitive heading could set off a cascade of responses that leads to degeneration of brain cells over time," Lipton explained.
I will refer to one of my all time favorite quotes from Winston Churchill, “scientists should always be on tap but never on top.” While this research is definitely valuable in that it raises awareness to a potential safety hazard in youth sports the advice falls short practically. Most headers will occur in practice drills and though at much slower speeds than what is experienced in games there is no reasonable way for all of those headers to be accounted for.
More practically the best strategy to avoid any potential cumulative effect of heading the ball would be to make sure soccer athletes do not play on more than one team in any given season and limiting the exposure to the sport to a maximum of 6-9 non-consecutive months a year. Ideally young athletes would play sports seasonally and that practice alone would significantly reduce the number of cumulative stress related injuries in any sport. However, in reality kids play some sports (soccer being on of the primary ones) nearly year round without a break in the action. In that case a header count may be valid but would require a designated official (headcounter if you will) to track the numbers but again would likely only be possible in a game setting. Executing headers with proper technique would also be wise in addition to a good strength and conditioning program in this case with an emphasis on muscles of the core and neck.
Another notion that was referenced previously is also worth expanding on; “When in midair, boys appear to have better spatial awareness, recognizing potential collisions and avoiding them.”
“Honestly, I don’t know a good way to word this. But if you watch, girls will focus on the ball and don’t see anything else around them when they go up for the ball. If it happens that a girl’s in the way, they end up colliding. Guys maybe have a little bit more peripheral vision. And I think guys manipulate their bodies better and are better at avoiding contact than girls.”
Peter Stogsdill, Head Girls Soccer Coach Westview High in San Diego, California.
I posed this hypothesis to a local high school soccer coach whom coaches both the boys and girls at the varsity level.
I am not sure I agree or disagree. My theory is that boys play other sports growing up, like baseball, football and basketball. Those sports require hand eye coordination. I think girls are not as used to balls in the air as boys are. I don't know if that makes a difference in awareness or not but just an opinion.
I loved this coach’s answer because it comes from someone with years of experience in the trenches and it also conveniently jibes with my strong belief on just how crucial the developmental years can be for the long-term performance and health of young athletes.
Girls often are not exposed to a diversity of sports during childhood and adolescence so they never develop certain fundamental abilities like how to sense, prepare and absorb impact, or the ability to track objects in flight. As an example a term I am sure you have heard many times before attached to a boy or even man that doesn’t throw a ball well is that he “throws like a girl.” This is of course a very misinformed concept. Boys and girls that don’t throw well is largely the result of a lack of exposure during a sensitive period when the skill of throwing is most optimally “learned.” If a skill isn’t experienced and experimented with during the developmental years the skill(s) will never fully mature.
So the idea that girls may lack the spatial awareness or hand-eye-coordination necessary to jump up in a crowd and efficiently head a soccer ball is very legitimate in my view. And while boys' gross motor skills (running, jumping, throwing) develop slightly faster, these underdeveloped abilities in females are more attributable to lack of experience. Girls can develop these abilities if they gain the appropriate experience and receive proper coaching. Again think about the throwing concept from above. I know plenty of female athletes that throw well with a mature throwing pattern and many boys that display an immature pattern. However, boys do tend to be more physically aggressive and impulsive, as revealed by studies of their brains. The pleasure center of the brain actually lights up more for boys when they take risks. That's not to say that girls aren't active and risk-taking, only that on average boys are more so. Heading a soccer ball is a fairly aggressive action especially in a game setting when going up in a crowd of competitors.
The Elephant in The Room
Children don't understand the word "concussion" very well. So what you'll find (is that) athletes will report symptoms but they don't attach the word concussion to it. If you ask if they've suffered a concussion, they'll say "no." But if you ask if they were hit in the head and saw stars or got dizzy, they may say "yes."
So coaches and parents should talk to their children in terms of symptoms and not necessarily using the word "concussion."
And it’s very important that the coach creates an environment where the young athlete is not fearful off being chastised for being a “baby” or “not tough.” If a child is fearful of losing playing time or being the subject of ridicule from coaches or teammates they are likely to withhold/hide vital information that could prevent a serious injury.
There are likely a host of factors and not a sole culprit for the prevalence of concussions in youth sports in general and girls soccer specifically. The things that are within our control to prevent head traumas are well thought out long-term athletic development programs, safe and properly fitted equipment, coaching of fundamental sport techniques such as heading the ball, and keenly aware coaches who create an environment that encourages athletes to speak up if they experience any symptoms.
Related Information and Resources
This is an excellent resource to post in the locker room or on the refrigerator.
Youth Concussions Signs and Symptoms Poster
Sample return to play protocol:
Athletes must be symptom free after each stage and pass no more than one stage per day.
1.Ride a stationary for 15 minutes.
2.Run for 10 to 15 minutes.
3.Introduce lower-body exercise. For example, run for five minutes, and then add pushups and sit-ups. Repeat the circuit once more. Adding pushups and sit-ups forces head movement.
4.Practice without contact. For example, participate in sport-specific drills.
5.Return to full practice.
CONCUSSIONS BY THE NUMBERS
*Girls playing high school soccer suffer concussions 68 percent more often than boys playing the same sport (Winter 2007-2008 edition of Journal of Athletic Training)
*Girls appear more susceptible to concussions in sports like soccer and basketball than boys (Winter 2007-2008 edition of Journal of Athletic Training)
*One study of collegiate soccer players found that females had 26 percent less total mass in their head and neck than males
*Roughly 40 percent of soccer concussions are the result of collisions between players. (U.S. Consumer Product Safety Commission)
*Approximately 13 percent are due to headers. (U.S. Consumer Product Safety Commission)
*Female soccer players are twice as likely to get concussed as males. (British Journal of Sports Medicine)