Lincoln's Melancholy

[RJNorton]

This is probably a long shot, but another thing that came to my mind was the possibility of a stroke. I realize strokes are rare in a person that age, but I was wondering about the possibility of bleeding in the brain causing permanent psychiatric illness. If this happened it could have changed Matthew suddenly and permanently if the damage in the brain never could heal and would still cause the same "insane" behavior 20 years later which Abraham observed. Like I said this is probably unlikely, but if it happened in a certain area of the brain, I think there can be psychiatric symptoms in some people.