I don't think age is affecting Anderson all that much. I'm certain he's slowed down a tad, but to coin a phrase, the man ages like a fine wine. He's had one lacklustre performance in the past however many years, and he even managed to win that. He's taken so little damage that he's aging far better than most.
As per your cheap GSP jab, at least Georges has never crumbled in the face of injury. Poor Andy hurts his ribs and almost loses a title fight. GSP tears his groin/fights with a flu and injured achilles and still dominates.
I guess we know who the true warrior is