Mentally slower and confused is not a good thing in a president. President Reagan was toward the end of his service but that was due to the tragic onset of Alzheimer's. His wife had to live with his deterioration the rest of his life and it must have been the hardest thing she ever had to do. I don't wish that on anyone for any reason.
Getting back to the point. Shouldn't a prez be razor sharp and at the top of his/her game intellectually mentally a well as physically emotionally and dare I say spiritually? The job takes a huge toll on anyone who holds it. They enter vibrant energetic dynamic youthful and they leave sapped of energy having aged tremendously. It is not a job for the faint of heart. I just don't know if Joe is up to it.