One of my colleagues here,
Diane Lefer, gave a lecture on madness and writing. She said something I liked so much that I hunted her down and made her give me a copy, under threat of extended pestering. She hastily obliged -- this is more of a summary of her speech than a direct quote of anyone, though:
Creativity and Personal Health and Creativity and Freedom are two books by Frank Barron and I find I don't remember which one I got the information from. But he, as a psychologist at Berkeley, did develop clinical tests to measure ego-strength and tested "high creatives." Found creatives both more primitive and more sophisticated. Slightly neurotic or even psychotic on measures of anxiety, depression, schizophrenia, and deviance, yet paragons of stability on ego-strength, power to rally from setback and cope with adversity. High creatives deliberately challenge, shake, unstabilize, frustrate, and disintegrate themselves in order to reassemble the parts better.
Sounds about right. Explains a lot, really.
