So much.
Too much.
In addition to just kind of forgetting where he is and where he is supposed to go, on numerous occasions that we know about, let's not forget the night Airforce One landed and the Prez didn't deplane for a full forty-five minutes. The official explanation is that he was "just working on something." But, think about it. In addition to the entire staff on the plane, he kept the ground crew, Secret Service, the helicopter crew, the WH staff, and others waiting almost an hour cause he was "just working on something." His aide and son-in-law left the plane twice and each time returned to the plane to see what was happening. This happened a mere two months ago. With so many other instances of strange behavior, it's hard to keep track.
None of this is normal. The people around him know this is not normal. I guess the big question is how long can they keep up the pretence?