Heading balls 'can damage brain'
Heading a ball can leave footballers with brain abnormalities and memory loss, a study has found.
Players most fond of the "header" suffer changes similar to those seen in patients with traumatic brain injury, scans have revealed.
Researchers in the US used an advanced magnetic resonance imaging (MRI) technique to study the brains of 37 amateur adult soccer players.
The technique, known as diffusion tensor imaging (DTI), can identify microscopic changes to the brain's white matter, which consists of billions of nerve fibres. Like communication cables, the fibres, or axons, connect different regions of the brain.
"We chose to study soccer players, because soccer is the most popular sport worldwide," said study leader Dr Michael Lipton, from the Albert Einstein College of Medicine in New York.
"It is widely played by people of all ages, including children, and there is significant concern that heading the ball - a key component of soccer - might cause damage to the brain."
Study participants reported that they had played football for an average of 22 years. They had also played for an average of 10 months over the previous year. The researchers estimated how often each player headed the ball on an annual basis.
To examine the state of players' white matter, they used fractional anisotropy (FA), a measurement of the movement of water molecules along nerve fibres. Abnormally low FA values, revealed by a DTI scan, are associated with mental impairment in patients with traumatic brain injury.
"The brain findings of the most frequent headers in our study showed abnormalities of white matter similar to what we've seen in patients with concussion," said Dr Lipton. "Soccer players who headed the ball above a threshold of 885 to 1,550 times a year had significantly lower FA in three areas of the temporal-occipital white matter."
Players who headed the ball more than 1,800 times a year were also more likely to score poorly in memory tests. The findings are published in the online edition of the journal Radiology.