Lipton surveyed 37 amateur players in a New York city adult soccer league, 29 of them men. The participants were asked about the amount of headers they did over the course of a season, as well as the number over their careers. Most had played an average of 22 years.
The players also had their heads scanned by something called Diffusion Tensor Imaging (DTI), an advanced MRI procedure that is able to look at molecular changes to the brain tissue. DTI produces a measurement, called fractional anisotropy (FA), which characterizes the movement of water molecules along axons.
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In healthy white matter, the direction of water movement is fairly uniform and measures high in FA. When water movement is more random, the FA number is smaller. Abnormally low FA within white matter has been associated with cognitive impairment in patients with traumatic brain injury.
Lipton's study, published online Tuesday (June 11) in the journal Radiology, found that the most frequent headers showed abnormalities of white matter similar to what the is found in patients with concussion.