Heading football may lead to brain injury: Study

Using an advanced magnetic resonance technique, called diffusion tensor imaging (DTI), researchers at Albert Einstein College of Medicine in New York studied the effects of soccer "heading" of a group of players and found that those who headed the ball with high frequency had brain abnormalities similar to those found in traumatic brain injury (TBI) patients.

"Heading a soccer ball is not an impact of a magnitude that will lacerate nerve fibers in the brain. But repetitive heading could set off a cascade of responses that can lead to degeneration of brain cells," said Dr Michael Lipton, who led the research.

According to the researchers, DTI helps see microscopic changes in the brain's white matter -- composed of millions of nerve fibers or axons that act like communication cables connecting various regions of the brain.

DTI produces a measurement, called fractional anisotropy (FA), of the movement of water molecules along axons. In healthy white matter, the direction of water movement is fairly uniform and measures high in FA. When water movement is more random, FA values decrease.

"Abnormally low FA within white matter has been linked with cognitive impairment in patients with TBI," Lipton said.

For the study, presented at the annual meeting of the Radiological Society of North America, Lipton and colleagues conducted DTI on 32 soccer players, aged over 30 years, all of whom have played the sport since childhood.

They estimated how often each player headed the ball on an annual basis and then ranked the players based on heading frequency. They then compared the brain images of the most frequent headers with those of the other players and found areas of the brain where FA values differed significantly.

Between the two groups, the researchers found significant differences in FA in five brain region of frontal love and in the temporooccipital region were found between the two groups.

"Those who headed most frequently had significantly lower FA in these brain regions," Dr Lipton said.

The five brain regions identified by the researchers are responsible for attention, memory, executive functioning and higher-order visual functions.

To assess the relationship between the frequency of heading and white matter changes, they also compared the magnitude of FA in each brain region with the frequency of heading in each soccer player.

"Our goal was to determine if there is a threshold level for heading frequency that, when surpassed, resulted in detectable white matter injury," Dr Lipton said.

The analysis revealed a threshold level of approximately 1,000 to 1,500 heads per year. Once players in the study surpassed that level, the researchers observed a significant decline in their FA in the five identified brain regions.

"What we've shown here is compelling evidence that there are brain changes that look like traumatic brain injury as a result of heading a soccer ball with high frequency," Lipton said.

"Given that soccer is the most popular sport worldwide and is played extensively by children, these are findings that should be taken into consideration in order to protect soccer players," he added.