Tag Archives: subconcussive hits

  Should tackle football continue to be played in its current form? A study with horrifying results that was published this week in the Journal of the American Medical Association raises that question once again. The study examined 202 brains of people who had formerly played football for varying lengths of time and at varying levels (some who only played pre-high school, some at high school, college level, semi-professional, or Canadian football league). They found the highest percentage of  the degenerative brain disease chronic traumatic encephalopathy (CTE) among former NFL players (110 out of 111 brains). However, the overall incidence of CTE was 87% when looking at all 202 brains. They also found that the 3 out of 14 former high school players had mild CTE, but the majority of former college, semiprofessional, and professional players had severe CTE.

The one thing to keep in mind is that the study only examined donated brains of former football players  - which means that the family members were concerned about CTE in the former player (perhaps there were symptoms suggestive of CTE). So we don't know the actual percentage of CTE in currently playing and former football players. But studies (here. here, and here) do show damage from hits received during football games and practice at even the grammar and high school level - and the damage can be from subconcussive hits.

But note that concussions and subconcussive hits (head trauma) also occur in other sports, such as soccer. Everyone agrees we need more studies, and we also need to rethink how some games are played in childhood to protect developing brains. From NPR:

Study: CTE Found In Nearly All Donated NFL Player Brains

As the country starts to get back into its most popular professional team sport, there is a reminder of how dangerous football can be. An updated study published Tuesday by the Journal of the American Medical Association on football players and the degenerative brain disease chronic traumatic encephalopathy reveals a striking result among NFL players. The study examined the brains of deceased former football players (CTE can only be diagnosed after death) and found that 110 out of 111 brains of those who played in the NFL had CTE. CTE has been linked to repeated blows to the head — the 2015 movie Concussion chronicled the discovery of CTE's connection to football.

In the study, researchers examined the brains of 202 deceased former football players at all levels. Nearly 88 percent of all the brains, 177, had CTE. Three of 14 who had played only in high school had CTE, 48 of 53 college players, 9 of 14 semiprofessional players, and 7 of 8 Canadian Football League players. CTE was not found in the brains of two who played football before high school.

CTE study several years ago by McKee and her colleagues included football players and athletes from other collision sports such as hockey, soccer and rugby. It also examined the brains of military veterans who had suffered head injuries. The study released Tuesday is the continuation of a study that began eight years ago. In 2015, McKee and fellow researchers at the Department of Veterans Affairs and Boston University published study results revealing 87 of 91 former NFL players had CTE.

McKee is chief of neuropathology at VA Boston Healthcare System and director of the CTE Center at the BU School of Medicine. Speaking about the new numbers, she says it's "startling to be able to gather 177 examples of CTE" in a relatively short period of time (the past eight years). "While we still don't know what the incidence is in the general population or in the general population of football players," she says, "the fact that we were able to gather this many cases [in that time frame] says this disease is much more common than we previously realized." "We need a very well-constructed longitudinal study," says McKee, "looking at young individuals playing these sports. We need to follow them for decades...." [Original study.]

 Study after study finds negative effects on the brain from playing football - here it is one season of high school football resulting in measurable brain changes. None of these players had a concussion during the season, and so the negative effects were from subconcussive head impacts or hits. Interestingly, those special helmets they wore to measure impacts showed no relationship with what the brain scans showed - so the helmets were basically useless in measuring subconcussive impacts. From Science Daily:

Head impacts from single season of high school football produce measurable change in brain cells

Repeated impacts to the heads of high school football players cause measurable changes in their brains, even when no concussion occurs, according to new research. Researchers gathered data from high school varsity players who donned specially outfitted helmets that recorded data on each head impact during practice and regular games. They then used experimental techniques to measure changes in cellular microstructure in the brains of the players before, during, and after the season.

"Our findings add to a growing body of literature demonstrating that a single season of contact sports can result in brain changes regardless of clinical findings or concussion diagnosis," said senior author Dr. Joseph Maldjian, Chief of the Neuroradiology Division and Director of the Advanced Neuroscience Imaging Research Lab, part of the Peter O'Donnell Jr. Brain Institute at UT Southwestern.

In the study, appearing in the Journal of Neurotrauma, a team of investigators at UT Southwestern, Wake Forest University Medical Center, and Children's National Medical Center evaluated about two dozen players over the course of a single football season.....During the pre-season each player had an MRI scan and participated in cognitive testing, which included memory and reaction time tests. During the season they wore sensors in their helmets that detected each impact they received. Post-season, each player had another MRI scan and another round of cognitive tests. 

Researchers then used diffusional kurtosis imaging (DKI), which measures water diffusion in biological cells, to identify changes in neural tissues. ....DKI also allowed the researchers to measure white matter abnormalities. White matter consists of fibers that connect brain cells and can speed or slow signaling between nerve cells. In order for the brain to reorganize connections, white matter must be intact and the degree of white matter damage may be one factor that limits the ability of the brain to reorganize connections following TBI.

Football has the highest concussion rate of any competitive contact sport, and there is growing concern -- reflected in the recent decrease in participation in the Pop Warner youth football program -- among parents, coaches, and physicians of youth athletes about the effects of subconcussive head impacts, those not directly resulting in a concussion diagnosis, researchers noted. Previous research has focused primarily on college football players, but recent studies have shown impact distributions for youth and high school players to be similar to those seen at the college level, with differences primarily in the highest impact magnitudes and total number of impacts, the researchers noted.

 In the last few years some people have raised the issue of whether subconcussions in chidren, teenagers, and adults playing football also leads to brain changes similar to concussions. Subconcussions are head impacts that aren't as strong as concussions, but they routinely happen to players in football games and practice. Research says YES - worrying brain changes are occurring from subconcussions, but long-term effects from them are currently unknown. Earlier research found that the brains of high school football players (who had only received head impacts during the season) don't fully heal during the off-season when football is not played. (More related posts on subconcussions: high school players, football before age 12, teen football players, soccer players). The research discussed below is ongoing research. From Medical Xpress:

Subconcussions cause changes to brain, study of college football players shows

The average college football player receives about 1,000 head impacts each season. Some of these hits result in concussions – traumatic head injury that results in short-term, and possibly even long-term, damage to brain function. But what are the effects of the hundreds of routine head impacts, called subconcussions, that occur during a four-month season of practice sessions and games?

A University of Virginia neuroscience Ph.D. candidate is trying to find out. Using functional magnetic resonance imaging – fMRI – Bryson Reynolds studied the brain activity and connectivity of a group of healthy college football players, before and after a competitive season, and compared the data to brain-activity scans of healthy male college soccer and lacrosse players, and to a control group of college male non-athletes.

He found that the football players experienced a disruption in "local functional connectivity" – the way different areas of the brain communicate with each other – while soccer and lacrosse players' brain activity did not noticeably change after a competitive season. The result for the soccer and lacrosse players was comparable to the control group, which also displayed no brain activity changes during a four-month period. "This is an important discovery regarding the football players because a similar disruption of local functional connectivity has also been found in athletes diagnosed with a concussion," Reynolds said.

"We have no ideas how these subconcussions might be affecting players' brains, but we are seeing concussion-like changes to the brain, at least in the short term," Reynolds said. "This does not necessarily mean that something bad is happening to the brain, but clearly some changes are occurring over the course of a season."

Neurologists know that concussions cause headaches, dizziness and sometimes loss of consciousness, and may also increase the risk for developing serious long-term neurodegenerative disorders, such as Alzheimer's disease, amyotrophic lateral sclerosis and chronic traumatic encephalopathy.

In other words, repeated head impacts over the course of a season, or perhaps a career, may be affecting the brain in ways not yet understood, but possibly similar to actual concussions. Reynolds' study did not include players who suffered concussions, and the subconcussions he observed were not causing perceptible problems or symptoms for the players. But the disruptions in brain activity recorded in the fMRI scans may indicate subtle changes that could be part of a larger picture. 

Very important research looking at some professional football players who started playing tackle football before the age of 12, and comparing them to those who started later. It discusses the issue of whether children should be playing tackle football before the age of 12 - these and other results suggest NOT. Wait till older (or don't play tackle at all).This article came from Boston University through Futurity:

Is This Kid Too Young For Football?

Researchers from Boston University School of Medicine found that former National Football League (NFL) players who participated in tackle football before the age of 12 are more likely to have memory and thinking problems as adults.

The study contradicts conventional wisdom that children’s more plastic brains might recover from injury better than those of adults, and suggests that they may actually be more vulnerable to repeated head impacts, especially if injuries occur during a critical period of growth and development. "

“This is one study, with limitations,” adds study senior author Robert Stern, a professor of neurology, neurosurgery, and anatomy and neurobiology and director of the Alzheimer’s Disease Center’s Clinical Core. “But the findings support the idea that it may not make sense to allow children—at a time when their brain is rapidly developing—to be exposed to repetitive hits to the head.

In the study, researchers reexamined data from Boston University’s ongoing DETECT(Diagnosing and Evaluating Traumatic Encephalopathy Using Clinical Tests) study, which aims to develop methods of diagnosing chronic traumatic encephalopathy (CTE) during life. CTE is a neurodegenerative disease often found in professional football players, boxers, and other athletes who have a history of repetitive brain trauma. It can currently be diagnosed only by autopsy.

For this latest study, published in the journal Neurology, scientists examined test scores of 42 former NFL players, with an average age of 52, all of whom had experienced memory and thinking problems for at least six months. Half the players had played tackle football before age 12, and half had not. Significantly, the total number of concussions was similar between the two groups.

Researchers found that the players exposed to tackle football before age 12 had greater impairment in mental flexibility, memory, and intelligence—a 20 percent difference in some cases. These findings held up even after statistically removing the effects of the total number of years the participants played football. Both groups scored below average on many of the tests.

Stamm says the researchers were especially surprised by the scores on a reading test called the WRAT-4, which has participants read words of increasing difficulty....The low scores may be significant, she says, because they suggest that repeated head trauma at a young age might limit peak intelligence. She emphasizes, however, that there may be other reasons for a low score, and that more research is needed.

The authors chose age 12 as the cutoff because significant peaks in brain development occur in boys around that age. (This happens for girls a bit earlier, on average.) Around age 12, says Stern, blood flow to the brain increases, and brain structures such as the hippocampus, which is critical for memory, reach their highest volume.

Boys’ brains also reach a peak in their rate of myelination—the process in which the long tendrils of brain cells are coated with a fatty sheath, allowing neurons to communicate quickly and efficiently. Because of these developmental changes, Stern says, this age may possibly represent a “window of vulnerability,” when the brain may be especially sensitive to repeated trauma.

Stern adds that a study by another group of researchers of the number and severity of hits in football players aged 9 to 12, using accelerometers in helmets, found that players received an average of 240 high-magnitude hits per season, sometimes with a force similar to that experienced by high school and college players.

With approximately 4.8 million athletes playing youth football in the United States, the long-term consequences of brain injury represent a growing public health concern. This study comes at a time of increasing awareness of the dangers of concussions—and subconcussive hits—in youth sports like football, hockey, and soccer. In 2012, Pop Warner football, the oldest and largest youth football organization in the country, changed its rules to limit contact during practices and banned intentional head-to-head contact. 

“Football has the highest injury rate among team sports,” writes Christopher M. Filley, a fellow with the American Academy of Neurology, in an editorial accompanying the Neurology article. “Given that 70 percent of all football players in the United States are under the age of 14, and every child aged 9 to 12 can be exposed to 240 head impacts during a single football season, a better understanding of how these impacts may affect children’s brains is urgently needed.”