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Heading football ‘linked to measurable brain decline’

Change in brain structure and decrease in verbal learning performance both observed over two-year study



Heading a football is linked to a measurable decline in the microstructure and function of the brain over a two-year period, a new study has revealed. 

As well as high levels of heading leading to a change in brain structure, it also impacts on verbal learning performance, the research found. 

“Our analysis found that high levels of heading over the two-year period were associated with changes in brain microstructure similar to findings seen in mild traumatic brain injuries,” Dr Michael Lipton, of Columbia University, said. 

“High levels of heading were also associated with a decline in verbal learning performance. 

“This is the first study to show a change of brain structure over the long term related to sub-concussive head impacts in soccer.”

The findings add further to growing evidence of the impact of heading a football, with inextricable links made to neurodegenerative disease and the frequency and strength of head impacts directly associated with Chronic Traumatic Encephalopathy (CTE). 

“There is enormous worldwide concern for brain injury in general and in the potential for soccer heading to cause long-term adverse brain effects in particular,” said senior author Dr Lipton. 

“A large part of this concern relates to the potential for changes in young adulthood to confer risk for neurodegeneration and dementia later in life.”

This new study examined changes seen over two years, and included 148 young adult amateur football players (mean age 27, 26 per cent women). 

The research team developed a specialised questionnaire for players to determine how often they hit the soccer ball with their head.

“When we first started, there was no method for assessing the number of head impacts a player experienced,” Dr Lipton said. 

“So, we developed a structured, epidemiological questionnaire that has been validated in multiple studies.”

The questionnaire consists of a series of questions about how often an individual plays, practices and heads the ball, and in what type of situations. 

Two-year heading exposure was categorised as low, moderate or high.

The players were assessed for verbal learning and memory and underwent diffusion tensor imaging (DTI), an MRI technique, at the time of enrolment and two years later. 

DTI characterises the microstructure of the brain by tracking the microscopic movement of water molecules through the tissue.

Compared to the baseline test results, the high-heading group (over 1,500 headers in two years) demonstrated an increase of diffusivity in frontal white matter regions, and a decrease of orientation dispersion index (a measure of brain organisation) in certain brain regions after two years of heading exposure.

In a second study, Dr Lipton and colleagues used DTI to investigate the association between repetitive head impacts from soccer heading and verbal learning performance.

Researchers analysed heading over 12 months prior to DTI and verbal learning performance testing in 353 amateur soccer players (age 18-53, 27 per cent female). 

Unlike previous research that has focused on deep white matter regions, this study employed a new technique, using DTI parameters to evaluate the integrity of the interface between the brain’s grey and white matter closer to the skull.

“Importantly, our new approach addresses a brain region that is susceptible to injury but has been neglected due to limitations of existing methods,” Dr Lipton said. 

“Application of this technique has potential to disclose the extent of injury from repetitive heading, but also from concussion and traumatic brain injury to an extent not previously possible.”

The researchers found that the normally sharp grey matter-white matter interface was blunted in proportion to high repetitive head impact exposure.

“We used DTI to assess the sharpness of the transition from gray matter to white matter,” Dr Lipton said.

 “In various brain disorders, what is typically a sharp distinction between these two brain tissues becomes a more gradual, or fuzzier transition.”

He added that grey matter-white matter interface integrity may play a causal role in the adverse association between repetitive head impacts and cognitive performance.

“These findings add to the ongoing conversation and contentious debate as to whether soccer heading is benign or confers significant risk,” he said.