Sports and recreational activities contribute to an estimated 1.6 to 3.8 million traumatic brain injuries annually in the U.S., and as scientists understand more about potential risks, there's increasing emphasis on developing new technologies to make sports safer.
The Food and Drug Administration recently authorized a new device, called a Q-Collar, that can be purchased without a prescription, but not all experts are sold on it.
Some experts told ABC News they were skeptical, citing what they said is a lack of evidence that the device can prevent traumatic brain injuries and that it may give wearers a false sense of security.
The Q-Collar, made by Q30 Innovations, is a slim, C-shaped device that fits around a player's neck, applying force to veins in the neck. The resulting increase in blood supply is meant to cushion the brain when the head is impacted.
In theory, this makes sense, said Adil Hussain, D.O., a physical medicine and rehabilitation doctor who specializes in brain injury medicine at Rancho Los Amigos National Rehabilitation Center in California.
"Think of it like a car accident: If your brain is a crash dummy, without a seat belt, it will fly around in the car," Hussain explained. "The purpose of the seat belt is to tie down the dummy to prevent it from moving within the car. Theoretically then, the Q-Collar is serving as a quasi-seat belt."
But Hussain and other experts warned that consumers should be aware of the device's limitations. They said that although studies show it might help prevent micro-injuries in the brain, the data stop short of showing the device can prevent serious brain injuries or concussions, a milder form of brain injury.
Experts also said increasing blood supply to the brain, which the Q-Collar does applying pressure to the neck, may not be safe for everyone.
"We must also consider what else could happen to the brain when the jugular veins are compressed," Hussain said. "The brain sits in an enclosed space within a hard skull, and thus has very little room to expand if put under additional pressure."
The device was primarily tested in teen and young adult athletes and shouldn't be used by people with a wide range of medical conditions, according to the FDA. And the FDA's authorization notice also makes it clear that the Q-Collar hasn't been proven to "prevent concussions or serious head injury."
"It's a troublesome FDA statement because it's hard to know exactly what [the devices] do for the consumer," said David Putrino, P.T., Ph.D., director of rehabilitation innovation and assistant professor of rehabilitation and human performance in the Mount Sinai Health System.
According to Putrino, the device's central claim -- based on specialized brain-imaging findings -- is that it might prevent brain damage in the long run by reducing micro-injuries. He would like to see additional long-term studies to prove that, especially because these images can be "difficult to interpret."
It would be better, Putrino added, to design studies that show the device is capable of reducing the symptoms of traumatic brain injuries, aka TBI, or long-term effects of repetitive head trauma, such as chronic traumatic encephalopathy, commonly called CTE.
"The bottom line is that we currently do not have a solid link between the imaging findings that the company is reporting and a propensity to go on and develop CTE or TBI," Putrino said.
Q30 Innovations highlighted the comprehensive review done by the FDA in evaluating eight years of numerous published studies.
"There was no rush to market for this product," said Julian Bailes, M.D., a neurosurgeon and chief medical adviser for Q30 Sports Science who's also chairman of the neurosurgery department at NorthShore University Health System.
In statement to ABC News, an FDA spokesperson said that "clinical study data supported its safety and effectiveness" to protect the brain from "repetitive sub-concussive head impacts."
According to Thomas Talavage, Ph.D., a brain-imaging expert who worked on the Q-Collar FDA submission, the proposed long-term benefit of the Q-Collar for youth athletes is valuable even if not yet more robustly documented.
"I think it's silly to not utilize it, because if it turns out that there is clinical utility, which I believe it does have, if it turns out at the end of 20 years, yes, this really matters -- we've got 20 years with athletes who have accumulated injuries that may be debilitating," Talavage said. "And we could have done something about that."
Tom Hoey, a co-founder and CEO of Q30 Innovations, said the company's research isn't finished and that there are plans for additional studies on the device.
"The clinical measures are important," he added, "and we will continue to explore these."
Nasir Malim, D.O., M.P.H., an internal medicine resident at Montefiore Medical Center in New York City, is a contributor to the ABC News Medical Unit. Dr. Leah Croll contributed to this report.