From the BPS Research Digest:
The idea that creative geniuses might not be entirely sane isn’t exactly new. But just how much do creative types have in common with people suffering from psychosis? Well, according to Daniel Nettle at the University of Newcastle, serious poets and artists have just as many ‘unusual experiences’ as people diagnosed with schizophrenia. What saves them from the disabling effects of schizophrenia is that they don’t suffer from the lack of emotion and motivation ‚Äì known as ‘introvertive anhedonia’ ‚Äì also associated with the illness.
Nettle used a measure of schizotypy on the participants in his study. Schizotypy is based on the concept that schizophrenia-like experiences can occur in everyone to some degree, and those with schizophrenia simply experience more intense and distressing versions of the milder experiences that other people have.