One season of football increases risk of brain injury

School-aged football players are at an increased risk of long-term effects in the brain after just one season of play, according to new research.

Two new studies conducted on children aged nine to 17 found changes in the area of the brain known as the default mode network (DMN), which is active while a person’s mind is wandering and responsible for processing emotions.

The effects were seen in both players with and without a history of concussion, but were even greater in those who had suffered at least one in the past.

This study adds to the mounting evidence that concussions due to football lead to serious changes in the brain including multiple sclerosis, impaired emotions, depression and most popularly CTE, which was found in former professional football player Aaron Hernandez.

Two studies conducted on young football players found changed in the brain caused by blows to the head while more players were impacted if they had a history of concussion

The studies conducted at UT Southwestern Medical Center in Dallas, Texas, and Wake Forest University in Winston-Salem, North Carolina, used Head Impact Telemetry System (HITS) helmets on players with and without a history of concussion for an entire season.

The results found that both types of players had changes in the DMN area, though those who had experienced concussions in the past showed greater brain disconnection than those who had not. 


The default mode network is a set of regions of the brain that are in communication with one another while during introspection and daydreaming.

Researchers found that daydreamers tend to have better-connected default mode networks when they’re relaxed, meaning that their brains work more efficiently. 

Evidence has pointed to disruptions in the DMN of people with Alzheimer’s and on the autism spectrum.

Decreased connectivity in the DMN can be caused by traumatic brain injury.

Previous research has shown that the more connected the default mode network regions are at rest, the more efficiently the brain works when it is actively engaged. 

Changes in this part of the brain have been linked to patients with Alzheimer’s and on the autism spectrum. But decreased connectivity in the area can be caused by traumatic brain injury.

‘The DMN exists in the deep gray matter areas of the brain,’ explained Elizabeth M. Davenport, Ph.D., study researcher at UT Southwestern’s O’Donnell Brain Institute. ‘It includes structures that activate when we are awake and engaging in introspection or processing emotions, which are activities that are important for brain health.’ 

In the first study, researchers observed 26 football players aged nine to 13 without a history of concussion to identify the effects that head trauma, not classified as concussions, had on the DMN.

The players wore the HITS helmets lined with sensors that measure the magnitude, location and direction of impacts to the head for an entire season.

Impact data from the helmets were used to calculate a risk of concussion for each player.

Pre- and post-season MRI scans were conducted and machine learning was used to analyze the data. Machine learning is a type of artificial intelligence that allows computers to perform analyses based on existing relationships of data.

The results found a growing change in the brain with increasing exposure to head impact.

‘Over a season of football, players are exposed to numerous head impacts. The vast majority of these do not result in concussion,’ said Gowtham Krishnan Murugesan, a PhD student. ‘This work adds to a growing body of literature indicating that subconcussive head impacts can have an effect on the brain. This is a highly understudied area at the youth and high school level.’ 

In the second study, 20 high school football players with an average age of 16.9 wore the HITS helmets for a season. Five of the players had experienced at least one concussion in the past and 15 had no history of concussion.

Before and following the season, the players underwent a brain scan.

The five players with a history of concussion had significantly lower connectivity between DMN regions. Players with no history of concussion had, on average, an increase in DMN connectivity.

The results demonstrate that concussions from previous years can influence the changes occurring in the brain during the current season, suggesting that there are long-term effects from concussions that affect brain function.

‘The brains of these youth and adolescent athletes are undergoing rapid maturation in this age range. This study demonstrates that playing a season of contact sports at the youth level can produce neuroimaging brain changes, particularly for the DMN,’ Murugesan said. 

Most professional football players begin the sport at six-years-old. 

Previous research has shown that football players who start tackle football from at least age 12 have impaired emotions and behaviors later in life, and the younger the players started, the worse their clinical function was. 

Dozens of other studies have been published this year specifically highlighting the effects football-related concussions have on the brain long-term.



Research published last week confirmed the strongest ever link between sports concussions and Alzheimer’s disease. 

Until now, doctors only considered severe traumatic brain injury a key risk factor for developing neurodegenerative diseases.

But the new study by Boston University School of Medicine (BUSM) has – for the first time – shown even low-impact injuries like concussion could have life-threatening consequences.   

They reached their conclusion by scanning the brains of 160 wounded war veterans after tours in Iraq and Afghanistan.

Using MRI imaging, the researchers measured the thickness of their cerebral cortex in seven regions that have been pegged at the ‘ground zero’ for Alzheimer’s disease.

They also scanned seven control regions – regions that tend not to be affected. 

They found that having a concussion was associated with lower cortical thickness in brain regions that are the first to be affected in Alzheimer’s disease.

Lead author, Dr Jasmeet Hayes, said: ‘Our results suggest that when combined with genetic factors, concussions may be associated with accelerated cortical thickness and memory decline in Alzheimer’s disease relevant areas.’ 


A study at Wake Forest School of Medicine has been examining the brains of high school football players.

One of the participants is the son of former Minnesota Vikings player Greg DeLong. 

The study published in the journal Radiology found measurable brain changes in teen players after a single season of ball – even without a concussion diagnosis.

Now DeLong is speaking out to say he would have seriously reconsidered his football career if he had known the risks.

‘Football’s important to us, but there are other things out there that are more important,’ DeLong told Good Morning America. 


The CDC has estimated that up to 3.8 million concussions occur in sports and recreational activities each year.

But some experts wonder if those numbers underestimate total brain injuries, as some individuals may not seek treatment for mild or moderate symptoms.

The agency has applied for federal funding to create a database in order to investigate sport injuries and brain diseases more in-depth. 

Meanwhile, the state of Texas has embarked on the largest ever study into concussions. 

State officials hope to track brain injuries among high school sports to discover whether more needs to be done to improve player safety and protect athletes.

The University Interscholastic League, Texas’ governing body for public high school sports, is partnering with the O’Donnell Brain Institute at UT Southwestern Medical Center for the project.

A state as large as Texas, which has more than 800,000 public high school athletes, would be a key step in developing a national database of brain injuries in youths, officials say.