Kevin: Does figure skating count...? The few sports mentioned were "non-contact".
Bill & Doctor X: I knew I can count on you to elucidate further. The article I read was very brief, giving some "findings", without going into the specifics of the study design.
I think the "self-selection" variable is a good point. Lets say they compare professional soccer players to professional boxers. I bet the latter, as a group, has more diminished mental functions. Is this due to more targeted, intentional hits to the noggin, or the fact that a rather "select" group chooses boxing as "viable" career? Personally, I suspect it's a combination of both.
Perhaps, Bill can do a new experimental design, with random assignments and pre/post tests. Doctor X can cut 'em up afterwards and confirm. (THIS IS A JOKE!)
[This message has been edited by david (edited 09-29-98).]