I do not think that Biden has Alzheimer’s. He seems to have dementia but of the vascular type. This means it is caused by multiple vascular events (strokes) in the brain. After each event a person can improve due to the brain’s finding new brain pathways to accomplish whatever was lost such as aspects of speech or right side usage etc. They seldom improve back to the pre-stroke level, however. With Alzheimer’s there’s never any improvement just plateau or steady decline. Perhaps Joe has had another vascular event so that he is staying in his comfortable surroundings in Delaware.
On the other hand, it is August and that is the time that politicians take vacation.