Lincoln's Melancholy

[RJNorton]

(10-10-2016 12:58 PM)Rob Wick Wrote:  Lincoln told Johnston "He is three years older than I, and when we were boys we went to school together. He was rather a bright lad, and the son of the rich man of our poor neighborhood. At the age of nineteen he unaccountably became furiously mad, from which condition he gradually settled down into harmless insanity. When, as I told you in my other letter I visited my old home in the fall of 1844, I found him still lingering in this wretched condition. In my poetizing mood I could not forget the impression his case made upon me."

I have always been curious about the case of Matthew Gentry. Louis Warren adds, "since he (Matthew Gentry) was the eldest son of 'the rich man' of a 'very poor neighborhood,' he was held in a particular high regard by his teachers and fellow pupils."

I am not familiar with how one can descend so rapidly with no apparent trigger. I can understand why Abraham was so shocked and bewildered, but what could have caused such an incredibly quick decline? (and still be in this "furiously mad" state 20 years later)

Could Abraham have been exaggerating/embellishing? Or can someone really go insane overnight?