Conversation so far:
What kind of illness did playwright Eugene O'Neillhave?
Eugene O'Neill faced a severe Parkinsons-like tremor in his hands.
How long did playwright Eugene O'Neill suffer from Parkinsons-like tremors?
The Parkinsons-like tremor in Eugene O'Neill's hands made it impossible for him to write during the last 10 years of his life.

Question: Is that what killed him?
Self-contained rewrite: Is Parkinson's Disease what killed playwright Eugene O'Neill?