Each year hundreds of thousands of teenagers engaged in sports sustain concussions, which can be caused by a violent shaking of the brain with our without a direct blow to the head. The number of reported concussions in football alone is 140,000 per year. Concussions (a/k/a mild traumatic brain injuries) also occur with great frequency from automobile crashes in which the brain, a Jell-O-like substance, is violently shaken and crashes into the skull as it accelerates toward the direction of the vehicular impact and then abruptly decelerates in the opposite direction.
Ignoring a concussion is a very bad idea. Chris Nowinski is a former Harvard football star, who after sustaining his own brain injury made it his life’s work to study the effects of concussion. He is the co-director of the Study of Traumatic Encephalopathy at Boston University School of Medicine. Nowinski says that helmets may prevent most severe brain bleeds, but they do not prevent the shaking of the brain causing contact with the inside of the skull. The insidious effects of concussion from such shaking may take years to materialize, according to Nowinski. Nowinski and his team study the brains of deceased NFL players and have concluded that repeat concussions can cause a protein in the brain called "tau" to become toxic to the brain cells and kill them. Nowinski has performed an autopsy on the brain of an athlete who died at 40 years of age and observed that "half of his brain cells were already dead." "The trauma may stop in your teens or early 20s, but the disease that started will progress and at some point in your 30s, 40s, or 50s, you’ll start showing symtpoms because so many cells have died that your brain can’t compensate anymore," according to Nowinski.
He recommends that teens should wait much longer than just a couple of days to return to contact sports following a concussion, and he notes that the symptoms last longer in females. The concussed athlete should be placed in a dark room with no stimulation, i.e., no video games, texting, or even homework. There should be as little brain stimulation as possible.