Soccer players hit the ball with their head. Hard. I'd be unsurprised if that resulted in measurable damage after a few years. In fact, it seems it does. http:

Soccer players hit the ball with their head. Hard. I'd be unsurprised if that resulted in measurable damage after a few years. In fact, it seems it does. http://www.scientificamerican.com/article/does-heading-a-soccer-ball-cause-brain-damage/ http://www.scientificamerican.com/article/does-heading-a-soc...