In hindsight, was Sean Connery already showing signs of having dementia when he was offered Lord of the Rings?

Of course, there was never a big public announcement to when started showing signs of dementia. But it's awfully interesting that he apparently didn't understand Gandalf or the Matrix role, but this is the same Sean Connery who did a high concept movie like Highlander.

It's arguable that his character was even less easy to understand than Gandalf: Doesn’t die unless he loses his head. Ages quite well. Progresses in the deathmatch that will ultimately have him fight each and every contender to the death. Yet decides to train one of them. So that said future opponent will become a better opponent.

Granted, he was never a Tolkien fan before, so picking up the story of a character who appears on almost every page of LOTR was probably a big ask.