This shouldn’t come as a surprise, but research shows that repeatedly hitting the head against a fast-moving object can lead to serious brain injury

PROBLEM: Although common sense dictates that hitting the head against objects moving at speeds of 34 miles per hour can cause serious injury, many soccer players repeatedly catch balls this way in training exercises and games. Curious and perhaps also worried, researchers led by Dr. Michael L. Lipton know if there is a threshold value for heading frequency that, if exceeded, will damage the brain.

METHODOLOGY: Researchers performed DTI, an advanced magnetic resonance technique that allows researchers to assess microscopic changes in the white matter of the brain in 32 amateur soccer players who have played the sport since childhood. They estimated the number of times each of the contestants led the ball annually, then analyzed their brain scans for signs of injury.

RESULTS: Soccer players who headed balls more than 1,000 times a year had significantly decreased fractional anisotropy, or FA, in regions associated with attention, memory, executive function, and higher-order visual functions. (FA is a measure that reflects the ability of water molecules in the brain to move steadily along the axons, and abnormally low white matter FA has been linked to cognitive impairment in people with severe brain damage.)