I put up a sentence regarding Mueller's health because anyone who watched his testimony has to be concerned with his demeanor. If you watch prior testimony he's given and compare it to his July 2019 testimony and there is a world of difference. I also provided two links for news articles regarding this so it's not just something I came up with, and one of the articles sourced a friend of Mueller's expressing the issue. I didn't post it to demean Mueller as he has a distinguished record and combat vet, so his lengthy service is unimpeachable. But people raised this same type of issue when Reagan was President, and then even more so after he left office, and it is I believe a valid point to raise.
The state of Mueller's health was raised by those that know him and how his demeanor markedly appeared different.[1][2]
Here is what is on Reagan's page "But there was also speculation over how long Reagan had demonstrated symptoms of mental degeneration."