Emily Dickinson is one of my favorite poets, but she was as crazy as Howard Hughes, Vincent Van Gogh, or Edgar Allen Poe.
Why was she so crazy. All i really know about her is that she is an american poet.
She dressed all in white, refused to leave her bedroom, and only sold 18 poems while she was alive, out of 1800 that she wrote.  This is the textbook definition of a hermit or recluse.
What made her so crazy though? Was it where she was raised, in Amherst, Massachusetts?
The cause of her reclusion is unknown to me, but i imagine it was due to some childhood trauma, bullying, or just being very different from other people.  Would that make sense?
The causes of mental disorders are usually very complex and they vary 
My favorite example from out modern era is the character Sheldon Cooper in the tv series "The Big Bang Theory".  His problem is autism, but he is definitely different from most people and doesn't seem to understand them.
The sitcom that is created by chuck lorre? i really like that show. i did not know it was autism that sheldon has
I'm pretty sure he is on the Autism spectrum.  I would call it functional autism.