A Wall Street Journal book review of The Creating Brain places creativity on a physical continuum, theorizing that it's related to psychosis.
Psychosis is marked by extreme delusions that are thought to reflect a loosening of associations among concepts in the mind. In mild form, this condition may enhance creativity by revealing to the genius, often after unconscious, nondeliberative thought, deep links between ideas that others could not perceive. Out of control, it can result in a ruminations that go more like this: I see the same person the train every day... he must be following me... the CIA has spies that follow people... the CIA must be persecuting me.
The subtitle of Nancy Andreasen's book is "The Neuroscience of Genius." The reviewer's use of this language grabbed my attention because I once heard someone say that the only truly logical people are autistic.