Why you should care
Because concussions are on the rise — but we still don’t know how to prevent them.
Bioengineer David Camarillo has suffered his fair share of blows to the head. The worst happened two years ago while biking across a San Francisco intersection. He passed in front of a car that had slowed to a near stop. Suddenly, the car accelerated, crashing into him. Camarillo’s memory of the collision itself remains murky, but he remembers full well its impact on his brain. The concussion he sustained left him mentally foggy, unable to read his watch or calculate tips. He developed PTSD. He hasn’t biked since.
The accident strengthened the scientist’s resolve to understand what happens to the brain during concussions, a timely topic. The number of concussions in the U.S. soared 43 percent between 2010 and 2015. Reports of chronic traumatic encephalopathy (CTE) in athletes and Iraqi war veterans have spurred an outpouring of research funding from the National Institutes of Health, Department of Defense, NFL and other organizations. In response, 38-year-old Camarillo’s Stanford laboratory has designed mouth guards outfitted with sensors that measure head movements, and then estimate how the brain twists and stretches during impacts in football and other contact sports. He hopes this data leads to safer protective equipment and regulations and lowers the risk of concussion. As it stands, Americans suffer an estimated 1.6 to 3.8 million sports- and recreation-related concussions each year.
Concussions happen when an impact causes the brain to tumble around in the skull, which can lead to confusion, unconsciousness and a number of other symptoms. Although most people recover from concussions, research suggests a link between repeated concussions and a risk of neurodegenerative diseases, such as dementia and CTE, long seen in boxers and more recently in ex-NFL players. Yet we know little about concussions, says Douglas Smith, director of the Center for Brain Injury and Repair at the University of Pennsylvania. The problem is, “ ‘concussion’ only describes the symptoms,” not their cause.
The good news: Advances in brain imaging and other technology have yielded a slew of metrics for measuring head impacts. The Holy Grail is to translate these data into biomarkers for diagnosing and preventing concussions, says Gerald Grant, a pediatric neurosurgeon at Stanford. To that end, researchers are racing to develop sensor systems that measure the forces the head sustains during an impact — with Camarillo among those in the lead. “He’s definitely a rising star,” Smith says. “Something like his mouth guard sensor will have really, really broad applications.”
Skyping from his office at Stanford, six-foot-three Camarillo chats near a blackboard scrawled with equations. He has golden boy, Abercrombie looks offset by nerdy black specs. He talks about growing up in a tight-knit family in Aptos, a sleepy beach town on California’s Central Coast. He played football and geeked out over rebuilding his beat-up 1967 Mustang. During his junior year, Camarillo started experiencing migraines, prompting him to wear a special padded attachment over his football helmet. “What’s going on in my head? What are these helmets doing for me?” he wondered. “That piqued my interest [in head injuries].”
Hoping to design jet engines, he juggled a mechanical and aerospace engineering degree with football at Princeton. But after an internship spent toiling away “on a little cog” of an aircraft engine, Camarillo switched gears, pursuing PhD research on surgical robotics at Stanford. He started his own lab in 2012, a few years after suffering a concussion from his first serious bike accident.
He had a hunch: the rotational acceleration hypothesis. Although we often imagine the brain bouncing against the walls of the skull in a concussion, Camarillo suggested twisting motions deep inside the brain are also responsible. Camarillo’s team recruited Stanford football players, local MMA fighters and boxers to wear their high-tech mouth guards. They measured the motions — linear accelerations — typically tracked in concussion studies but also looked at rotational accelerations. Rotational acceleration proved to be a better predictor than linear acceleration.
Camarillo’s findings suggest we might one day better predict concussions, even factoring in athletes’ or soldiers’ possible genetic predispositions. Doctors could use Camarillo’s mouth guard to decide whether to sideline athletes for assessment. That’s important, since sustaining a concussion dramatically raises the risk of future concussions, but many people don’t realize they’ve had one. “If we could understand the physics behind concussion, that provides a basis for rational design of protective equipment,” Camarillo explains.
Many researchers use sensors installed on helmets or skin patches, but these move significantly relative to the head, meaning they might not accurately reflect the forces impacting the brain. But the jaw is “intimately connected to the skull,” says Peter Cripton of the University of British Columbia. “That’s one of the novel and very promising aspects of [Camarillo’s] approach.”
But “it’s still very early days,” Smith says. That’s largely because, “in concussion, there is no gold-standard test.” Camarillo’s fine with waiting, content to gather data for now. And he’s venturing beyond the brain. Today, he’s measuring how embryos respond to force, which could lead to a faster, more precise method of screening them for in-vitro fertilization (IVF). Today, IVF clinicians see a dismal 30 percent success rate, often implanting multiple embryos to increase their odds, sometimes causing risky pregnancies. But Camarillo found that he could measure the rigidity of embryos to find those more likely to form a healthy cluster of cells known as a blastocyst. The technique involves gently tugging the embryo with a tiny pipette to measure its rigidity. In clinical trials, it’s identified viable embryos with 90 percent accuracy.
Here too, Camarillo draws on personal experience. After an emotional IVF journey, his wife eventually became pregnant with their daughter; they’re now awaiting the birth of a son. Asked if he would let his kids play football or other contact sports, Camarillo wavers. “I’m still scared about it, but I’m not ready to say no,” he says. Athlete that he is, he uses his fear as fuel: “My fear motivates me.”