Yeah, I dont think typical “cognitive decline” comes in episodes like that, as advanced as the President seems to be. Moments or periods of lucidity, yes, but not decline like he exhibited.
Yes. With Alzheimers a person can have sudden mental clarity relatively speaking which is a joy to experience. But it is only ‘clarity’ in contrast with the usual decline so its not like the person is suddenly well. But better enough to have a conversation.
But these good moments are not predictable.