He has bipolar disorder, schizophrenia, autism, Parkinson and alzheimers.
He likes making music, painting and drawing.
He's done a ton of crazy shit, like running away from home and joining the circus, braking into an old lady's home because he taught she was Satan, etc, etc.
Kurt Cobain, the lead singer of Nirvana, admired Daniel.
I highly suggest you watch the documentary on him, the Devil and Daniel Johnston.