Pediatric experts in sports medicine and neurology have reviewed three-decades of studies related to sports concussion-research. Despite their best efforts, the researchers say that there isn’t enough evidence to answer many burning questions parents might have about contact sports, including what age is safest to start playing.

The most popular contact sports in the United States are American football, ice hockey, mixed martial arts, boxing, wrestling and rugby. Due to frequent high-impact contact, like tackling, it is possible for a child to acquire sports-related concussions.

Concussions are the most common brain injuries, accounting for about 80% of all traumatic head injuries suffered in North America. The word “concussion” comes from the Latin concutere, which translates “to shake violently.” It is an apt word for concussions, since the brain — which is surrounded by spinal fluid and enclosed in the skull — literally starts shaking when the skull is hit, inflicting bruising, nerve, and/or blood vessel damage. 

Symptoms of a concussion include headaches, nausea, memory loss, and lack of coordination. In most cases, the symptoms go away in a few hours or days. However, in 14-36% of cases, the symptoms can last for months or even years.

Recent studies have associated contact sports that can result in concussions to chronic traumatic encephalopathy (CTE) — a degenerative brain disease in which protein clumps form in the brain, killing neural cells. The damage is irreversible, resulting in radical mood and behavioral changes. As the disease progresses, some patients may experience problems with thinking and memory, including memory loss, confusion, impaired judgment, and eventually progressive dementia. 

According to a recent study, every year of playing tackle football raises the risk of developing CTE by 30%, while every 2.5 years of play doubles the risk.

Since the brains of children are still developing, many worried parents would like to know what would be a safe age for their kids to start a contact sport. They might not be satisfied by the results of a three-decade review recently published in the journal JAMA Pediatrics, which found no evidence that might point to a safe age to start playing contact sports.

“Parents worry, ‘Is one concussion to my child going to result in him having dementia at age 50?’” said lead author, Dr. Frederick Rivara, who is a pediatrician and injury prevention researcher at the University of Washington’s medical school. “And the data are pretty clear that the answer is no.”

However, it’s not cleat at all what number of concussions would be dangerous or what are the long-term consequences of suffering multiple concussions before becoming an adult.

The panel of experts who authored the new study did fill in some of the blanks. Their main findings were:

• Children should be trained on how to avoid collisions;
• There is no conclusive evidence that kids face a higher risk for acquiring sports-related concussions;
• There is no conclusive evidence that multiple concussions result in long-term neurological changes;
• Technologies designed to assess head impact trauma and advanced brain imaging techniques are not reliable enough to draw conclusions about the risks children face when practicing contact sports;
• Helmets should be worn in high-impact sports. However, there is no conclusive evidence that headgear prevents concussions in rugby and soccer.
• Teen girls face higher risks than boys for concussions;
• Hockey body checking bands reduced concussions in players age 13 or younger;
• Limiting contact in youth tackle football reduced the number of head impacts;

Dr. Bennet Omalu — a forensic pathologist whose discovery of chronic traumatic encephalopathy (CTE) was portrayed in the Will Smith film “Concussion” — is much more risk-averse when it comes to letting kids practice contact sports. In his book, “Truth Doesn’t Have a Side: My Alarming Discovery about the Danger of Contact Sports”, Omalu warns that children who play football, hockey, or lacrosse could face important health consequences. He’s even gone as far as saying that letting kids play football is simply “child abuse”.

“I take classes in child abuse recognition every few years in order to maintain my license to practice as a physician. The fundamental definition of child abuse is the intentional exposure of a child to the risk of injury. That injury does not have to occur,” Omalu told Today.com.

“We wouldn’t give a child a cigarette to smoke because a cigarette is potentially harmful. But we would put on a helmet on the head of a child and send him out on a field to play a game whereby he sustains repeated blows to his head, to suffer sub-concussions and concussions.”

To support his claims, Omalu cites two recent studies conducted in Sweden. The researchers included 1.1 million children in their studies, whose progress was followed for 41 years. Those who suffered just a single concussion as a child were more likely to die before the age of 42, especially through violent means. They were also 2-4 times more likely to commit suicide as an adult and 2-4 times more likely to suffer from major depression.

“He is more likely to have diminished intelligence and is more likely to be less gainfully employed as an adult. He is more likely to become a drug addict or alcoholic; and is more likely to engage in violent or criminal behavior,” Omalu says.

Omalu advises parents that they shouldn’t let their children play contact sports before they turn 18.

However, Rivara says that the risks of contact sports should be considered against a backdrop of growing obesity rates among children. The 2018 Physical Activity Guidelines for Americans by the US Department of Health and Human Services recommends moderate to vigorous physical activity every day and vigorous activity at least 3 times per week.

“The last thing we want to tell kids is not to be active,” said Rivara, a pediatrician and injury prevention researcher at the University of Washington’s medical school.

The study published by Rivara and colleagues was funded by US Lacrosse, USA Football, the American College of Sports Medicine, and USA Rugby.