I don't know if it's a documented side effect of prednisone (lord knows it has enough of them anyway!) - but I certainly had it when I was on prednisone. the longer I was on it, the worse it got. It very well could be dose related, too, because I did notice it was worse when I was on the highest dose (120 mg daily at one point for over a year!). Fortunately, I was eventually able to get off the prednisone, but still need to go on it periodically for asthma, lupus and arthritis. I do notice a change in my memory status whenever I am on it, although definitely not as bad as when I was on the high doses for so long.