A career of heading a soccer ball may raise the risk of dementia, according to a small new study.
Six longtime soccer players who died with dementia were found to have brain injuries from repetitive trauma.
The injuries are the same kind found in American football players, boxers and soldiers hit by explosions. They include a condition known as chronic traumatic encephalopathy, or CTE, which is linked to declining mental function and mood disorders.
WATCH: Soccer May Pose Risk of Repetitive Brain Injury
While concussions are relatively rare in soccer — the port the rest of the world knows as football — players regularly hit the ball with their heads. That's on top of the collisions common in any contact sport.
“The key thing in (soccer) is, players are exposed to lower impact but very high number of blows to the head,” says neurology professor Helen Ling at University College, London, lead author of the new study.
Injury happens because the human brain has the consistency of a firm pudding, “but your blood vessels are just a little bit tougher,” says Ling's colleague in London, neuroscience professor John Hardy. “And so, if you do a rapid rotation, they act like little cheese wires and do bits of damage around them.”
But how serious that damage is in soccer players is unclear. Ling says there have only been a few studies, using brain scans or blood tests, and the results have been contradictory.
Examining a patient's brain under a microscope can provide definitive evidence, but that has to wait until the patient dies.
One of the study authors has been treating retired soccer players with dementia since 1980. Six of them donated their brains for research when they died.
In the new study, in the journal Acta Neuropathologica, all six brains showed signs of damage, and four had CTE.
“We're becoming increasingly aware that the risk is higher than we thought,” says Thor Stein, a neuropathologist at Boston University and the U.S. Department of Veteran Affairs, who was not involved with this study.
What's the risk?
But it's still early, he cautions.
“Soccer is even further behind than American football in terms of trying to figure out what is the risk. We don't know. We can't answer that with this kind of study.”
While many American parents are reconsidering letting their children play football, the authors don't recommend pulling kids off the soccer field.
The health and social benefits of playing sports are well established. And, Hardy adds, these six patients played soccer “probably every day of their lives for 25 to 30 years, probably many hours a day. This is very different from a casual, weekend player or a school player. It's just a different order of magnitude of contact.”
Ling hopes the study will spark more research, starting with figuring out how common dementia is among football players as they age.
British soccer associations have pledged to back more studies on the subject.