Like [psychologist David] Weeks (p. 137), we have found that the dividing line is not clear-cut, that is, between functional eccentrics and those who have a (history of ) mental disorder. Some of our artists demonstrate both. Their quirks not withstanding, settled, contented eccentrics should not be labeled as mentally ill in the absence of current distress or dysfunction.
Mental disorders purported to cause or accompany eccentricity in at least some instances include cyclothymic and bipolar disorders, Asperger’s disorder, schizotypal and schizoid personality dis-orders, obsessive-compulsive disorder, and schizophrenia. Weeks did not report on mood disorders in his subjects.
Nancy Andreasen, a neuroscientist and psychiatrist, has shown a strong association between mood disorders and creative writing ability (“The Creating Brain: The Neuroscience of Genius,” New York: Dana Press, 2005). In one of her studies, 24 of 30 professional writers (80%) had mood disorders; none were schizophrenic. (Andreasen was not studying eccentricity, but this striking link between creativity and mood disorder is pertinent.)