Heading a football can alter brain structure and chemistry, even without causing concussion or impairing thinking, a controlled trial using MRI scans has shown.
In the study, fifteen adult male players were asked to head a football 20 times in 20 minutes.
While no immediate cognitive problems were observed, the MRI scans revealed small but measurable changes to the brain.
Dr Danielle McCartney is a co-author of the study at the University of Sydney’s Lambert Initiative for Cannabinoid Therapeutics.
The researcher said: “These findings suggest that even routine, symptom-free heading can produce subtle changes in the brain.
“The next step is to understand whether these changes accumulate over time, and what that might mean for player health in the long run.
“In the meantime, we’re adding to calls for soccer players to exercise caution and perhaps consider whether extensive heading is necessary, particularly in training.”
The study, led by the University of Sydney and conducted at Neuroscience Research Australia, used MRI scans alongside blood and cognitive tests to assess the impact.
Balls were launched at consistent speeds by a machine to ensure a controlled setting. Each participant also completed a session involving kicking, rather than heading, to isolate the specific effects of heading.
MRI scans showed altered chemistry in a brain region involved in motor control and reduced electrical conductivity across several areas, indicating changes in energy use and signal transmission in white matter.
Blood tests found elevated levels of two proteins – GFAP and NFL – which are established biomarkers of brain injury and increased dementia risk.
However, these increases were significantly lower than those seen in people with concussion or dementia.
Dr Nathan Delang, led the research as a PhD candidate at Griffith University and is now a postdoctoral researcher at the University of Queensland.
He said: “This study does not demonstrate heading causes dementia.
“Our take from the higher presence of these proteins, and the study overall, is that heading the ball can cause subtle disruption to brain cells, even without obvious symptoms.
“Elevated levels of these biomarkers indicate brain cells have been disturbed at a microstructural level.
“The clinical and long-term significance of such small elevations is still being studied—particularly in relation to how much, and what pattern, of exposure might lead to effects on brain structure and function.”
