Heading a football too often can lead to brain damage, scientists have warned.
New research by the Radiological Society of North America found that football players who frequently headed the ball had brain abnormalities similar to those found in patients with traumatic brain injury (TBI).
According to the report, executing more than 1,000 to 1,500 headers a year can lead to damage in five regions of the brain responsible for attention, memory, executive functioning and higher-order visual functions.
To reach their findings, researchers used a magnetic resonance technique called diffusion tensor imaging on 32 amateur football players.
They had an average age of 30.8 years and had played the game since childhood.
The scientists found that water movement in the brain's white matter was less uniform in players who used their head more often, a phenomenon which is linked to cognitive impairment in patients with TBI.
Michael Lipton, associate director of the Gruss Magnetic Resonance Research Center at the Albert Einstein College of Medicine, in New York, said: "Heading a soccer ball is not an impact of a magnitude that will lacerate nerve fibres in the brain.
"But repetitive heading could set off a cascade of responses that can lead to degeneration of brain cells.
"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."