Previous studies have shown that sports-related concussions may be caused by series of hits to the head over time rather than a single blow. Now new research suggests that sustaining repetitive hits may not affect all athletes in the same manner and that a select number could experience diminished cognitive function after a single season.
In the study (subscription required), researchers examined cognitive effects of repetitive head impacts over a single season among college football and hockey players. CNN's The Chart blog reports:
In a study of college football players at three Division I universities, [researchers] found that subconcussive hits were not causing the dramatic lapses in cognition that might be considered a precursor to [chronic traumatic encephalopathy]. But when they re-examined the data, they found something slightly alarming.
A significant subgroup of the contact sport athletes - 22% - performed worse than expected on tests of verbal learning, compared with only about 4% of the non-contact sport athletes.
The data were gathered by nestling sensors in the helmets of 214 varsity football and hockey players and recording subconcussive hits during one full season. The sensors measured things like the force, location and rotation caused by hits to the head.
The contact sport athletes were compared to a control group of 45 athletes participating in non-contact sports like track, crew and Nordic skiing. Each group took cognitive tests before and shortly after the season.
According to the study, published in the journal Neurology, by the end of the season some contact sport players came up short on those tests.
As discussed here previously, research is underway here at Stanford to measure the number, force and direction of head impacts during games and practices for football players and athletes in other contact sports. In the intial study, researchers equipped Stanford football players with high-tech mouthpieces to determine what types of collisions cause concussions and whether there are any positions or plays associated with a greater risk of traumatic brain injuries. They intend to expand the study to the women’s field hockey and lacrosse teams.
Previously: High-tech mouthpieces used to advance medical understanding of concussions in football, Researchers develop new test for diagnosing concussions on the sidelines and When can athletes return to play? Stanford researchers provide guidance
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