I always say I have cotton brain when I was on Pred. It feels like my head is full of cotton and it takes a long time for any thought to complete. I was never on Pred for a very long time, but it happened every time. That on top of how moody I got would make me hate Pred, but it always got me out of the really bad flares quickly.
From talking to some friends, they have it too but to different extremes.