Classics Without All the Class discussion

Was Chief Bromden mentally insane when he was committed to the hospital 10 years ago? How does he appear when we first meet him? What is the cause of his hallucinatory fog—his medications or his paranoia or...?

I think Chief Bromden was just worn down by the Combine - all of the horrible events and sadness that the world had dealt him. The annihilation of his people and their way of life as their land was taken away and the men succumbed to alcoholism, his wartime service, coupled with his own, seemingly justified, feeling of invisibility eventually overwhelmed him. The fog, probably partly induced by the medication but also seemingly encouraged by him, protected him when he was in danger of having to confront his feelings or a situation that was too much for him. I don't think he was ever insane - just overwhelmed and worn down to the point of exhaustion - a victim of a lifetime of awful circumstance.