Given the task definition and input, reply with output. In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.

"If you’re going to play [tackle] football, put it off until the body matures completely, until the body size has caught up with head size, until the muscles are coordinated," McKee said. 
  
 Cassandra Keck took some comfort in hearing the diagnosis. The man she met and married had been smart, kind and industrious. But then he started to change; his memory deteriorated and he became violent and abusive. 
  
 Keck had maintained a 3.8 GPA at Harrisonville High in Missouri and was able to keep his grades high in his freshman year at the University of Missouri. That all changed after he transferred to Missouri State University and sustained his second college concussion playing linebacker. 
  
 Michael took a year off football to recover. When he tried to start working out with the team again, his headaches would flare and his vision would fade to black. Though his vision would return eventually, it was frightening and Keck told his coaches he couldn’t come back. 
  
 “He couldn’t read his books," Cassandra said. "The words would get all scrambled. He’d get angry and punch the book and throw it across the room. He couldn’t read, so he couldn’t study. He felt like he was failing. He just wanted to graduate from college.” 
  
 About a year before he died, he had to stop working. “Having to be somewhere on time was very stressful,” Cassandra said. “I’d have to put his shoes and socks and hat by the door so he knew where everything was. I’d have to get his shirt and pants ready.” 
  
 Head hits and later symptoms 
  
 There still isn’t enough evidence to suggest that youngsters need to give up tackle football, experts told NBC News. It's unknown how many people end up with permanent debilitating symptoms as a result of hits on the field, said David Hovda, a professor of neurosurgery and director of the Brain Injury Research Center at the University of California, Los Angeles, who is unaffiliated with the new study. 
  
 Even if it’s a small percentage, “we still need to do something about it,” Hovda said. “Every person is important. But we have to be cautious about changes that affect everybody.” 
  
 If the percentage is much larger, say one-third of players, then “we have a real problem that needs to be fixed," Hovda said. 
  
 Another question is whether head hits among some youngsters can be linked to CTE symptoms later in life. 
  
 “Certainly we have known that CTE changes in the brain can be found in younger players," said Dr. Julian Bailes, medical director of Pop Warner football, who is unaffiliated with the new study. “But I don’t think that any research, and not the [new] case report, necessarily correlates with football participation at a young age. In my opinion, it is more likely that the exposure that he got in high school or college, or even doing other activities, led to the accrual of CTE changes.” 
  
 Related: Will Soccer's New Header Rules Make Kids Safer 
  
 Bailes, clinical professor of neurosurgery at the University of Chicago Pritzker School of Medicine and the chairman of the department of neurosurgery at the NorthShore University HealthSystem reported on the 2009 death of Chris Henry, the only active NFL player to die and have CTE at age 26, with forensic pathologist Dr. Bennet Omalu. 
  
 Watch: Bengals mourn the death of receiver Chris Henry 
  
 The hits little kids sustain playing tackle football rarely lead to concussions, Bailes said. 
  
 “For instance, in Pop Warner football, we think that currently the concussion rate is only 1 percent annually for players, while they are receiving about 100 cranial impacts per season, almost all of low velocity,” he added. “However, high school players hit at high velocity (high g-forces) and at about 600-800/year, and college approximately 1000/year. “ 
  
 Taught to play through pain 
  
 For her part, Cassandra hopes that in telling Michael’s story, people will better understand the dangers of concussions. ||||| Also Meets CME requirements for: 
  
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Before he died of a heart condition at age 25, Michael Keck told his wife that he wanted to donate his brain to Boston University. The former football player thought he had chronic traumatic encephalopathy (CTE), NBC News reports, the degenerative brain disorder caused by repeated blows to the head that has made headlines in recent years for affecting NFL players. Doctors, performing an autopsy on Keck's brain, confirmed his self-diagnosis in a case study published Monday in JAMA Neurology. "It was the worst CTE I've seen in an individual this young," study coauthor Dr. Ann McKee says. Keck's 16-year football career began when he was 6 years old, the study notes. During that time, he sustained more than 10 concussions, the first when he was 8. "That's a lengthy exposure," says McKee. "Brain injury is cumulative." As a freshman playing for Missouri State, Keck momentarily lost consciousness after a hard hit. That was followed by symptoms, such as blurry vision, headaches, and forgetfulness, which forced him to quit playing football his junior year. Previously having a 3.8 GPA, the study notes, Keck "left school with a GPA of 1.9, 12 credits short of earning his bachelor degree." Symptoms, including "feelings of worthlessness" and "suicidal ideations," persisted until his 2013 death of an unrelated congenital heart defect. Some, including the doctor who first identified CTE, have called for an end of high-impact sports for kids. Others, though, say the concern is overblown. The medical director for Pop Warner football tells NBC that the Keck study doesn't indicate the brain trauma was the result of childhood injuries. "It is more likely that the exposure that he got in high school or college, or even doing other activities, led to the accrual of CTE changes," he says. (Researchers recently found CTE in 96% of 91 deceased NFL players.)