Shakespeare wrote all there is that we need to know about dementia in 'King Lear.'

The king stood in a pool of blue light, unmoored.

Thou whoreson zed! Thou unnecessary letter! My lord, if you will give me leave, I will tread this unbolted villain into mortar, and daub the wall of a jakes with him. *all cheer for Shakespearean insults*

Shakespeare speaks for the human heart but Dickens speaks for the social man and for injustices.

I gave you all!" screeched Lear, waving a palsied claw at Regan.
"And you took your bloody time giving it, too, you senile old fuck," said Regan.

I will do such things,--
What they are, yet I know not: but they shall be
The terrors of the earth.