Extra protection?

By Gina Kolata
I’m a reporter covering health.

Now that the N.F.L. season has begun, you may have noticed football players wearing a strange sort of cover over their helmets. It’s called a Guardian Cap, and it adds a layer of foam to the outside of the helmet, with the aim of reducing brain injuries.

N.F.L. players have worn the caps during summer practice for the past few years, but this is the first season the league is allowing them in games. A handful of players wore them during the opening weekend.

The company behind the caps, Guardian Sports, says they reduce the force of the impact when a player’s head is hit. But what does that mean? And do they protect against concussions?

Erin Hanson, Guardian’s founder and owner, said an N.F.L. study found that when players used Guardian helmet caps in practice, the number of concussions fell by more than 50 percent.

Yet, Guardian also has a disclaimer on its website: “No helmet, practice apparatus or helmet pad can prevent or eliminate the risk of concussions or other serious head injuries while playing sports. Researchers have not reached an agreement on how the results of impact absorption tests relate to concussions.”

In a telephone interview, Hanson emphasized that it was unrealistic to think that the cap would prevent all concussions.

“Football is a dangerous collision sport,” she said. “No doubt about it.”

I asked brain trauma experts to weigh in. What sort of protection can players realistically expect if they wear the helmet caps? Today’s newsletter explains what the extra padding could do for concussions, and for C.T.E., the long-term condition that plagues many players later in life.

An injured football player lies on his side on the field while other players check on him.
Tua Tagovailoa of the Miami Dolphins, center, suffered a concussion during a game on Thursday. Lynne Sladky/Associated Press
The trouble with concussions
Don’t count on these new helmet caps to protect against concussions, experts said.

“The problem is that people confuse head injuries with brain injuries,” Dr. Jamshid Ghajar, a neurosurgeon and the president of the Brain Trauma Foundation, told me. “Helmets definitely help with head injuries,” like a fractured skull or injuries to the scalp, he noted, but they don’t help with concussions.

Concussions arise when a person’s neck bends and twists after the head is hit. That was apparent on Thursday, when the Miami Dolphins quarterback Tua Tagovailoa suffered a concussion from a tackle that caused his neck to turn sharply.

“The neck is very flexible,” Dr. Ghajar said. “Its movement causes the brain injury problem, making the front part of the brain whiplash.” The front of the brain, he added, “is where we see concussions and severe brain injury.”

Race-car drivers wear helmets that actually protect them from concussions, Dr. Ghajar noted. The helmet holds the neck rigid so it cannot move in a collision. “Drivers have had collisions at over 200 miles per hour and no brain injury,” he said.

“Helmets and padding work if you have an iron neck,” Dr. Ghajar added.

Tricky data
But what about that N.F.L. study of players that Hanson cited, showing a 50 percent reduction?

“That was a pleasant surprise,” Dr. Javier Cardenas, a senior medical adviser for the N.F.L., told me. It happened two years in a row, he added, which led him to conclude that the caps “definitely” reduced the risk of concussions.

Dr. Daniel Daneshvar, a concussion expert at Massachusetts General Hospital, is not convinced. He noted that the N.F.L.’s study had relied on players reporting their own symptoms, which makes it hard to draw conclusions.

The problem, Dr. Daneshvar said, is that players may not always recognize symptoms of a concussion, or may ignore them. And if they think their new helmet caps are protecting them, they may be less likely to report a concussion.

Hope for C.T.E.

C.T.E., or chronic traumatic encephalopathy, is the condition that most frightens many football players. It can lead to memory loss and behavioral changes years later. And it results from not just the traumatic impacts that cause concussions, but also the accumulation of smaller hits to the head that every football player endures.

The extra padding of helmet caps could, in theory, help reduce that. “Anything that decreases force to the head will decrease the risk of C.T.E.,” Dr. Daneshvar said.

Kylen Granson, a tight end for the Indianapolis Colts, has said he plans to wear a helmet cap all season. “I would be remiss in not taking every precaution that’s available to me,” Granson said in a recent Instagram video. “I’m going to get married this coming year. I want to be able to remember our first dance 30 years from now.”

The N.F.L. has cited a lab study that found Guardian caps reduced force by 10 percent. That “would probably decrease C.T.E. risk,” Dr. Daneshvar said, though he cautioned that the lab study used dummies with rigid necks, which he said created “ideal circumstances to maximize the effect.”

“My analogy would be a filtered cigarette,” Dr. Daneshvar said. “It absolutely decreases the rate of cancer, and it might be a step in the right direction, but it’s not the entire solution