Docs who specialize in the brain will tell you, we are all brain-damaged, to some extent. Look no further than this thread ...

Seriously though, I agree. It would be like trying to determine the number of riders who soiled themselves during a crash, such statistics are not even kept, as far as I know. So it would be a fool's errand to even try to document the numbers and come up with a definitive answer without any data, one would think.