I guess we're talking US football then? I've noticed this trend among rugby players I have known. They seem to have abnormally bad cognitive skills. Especially the ones who played as children. Not very fast to process and apply information and that. Is this a result of neuron damage? I don't like to generalise. It could be just coincidence.
I'm kind of slow too actually. I don't suppose it's coincidental that I took many a bang to the head when I was wee.