In 1993, Kay Redfield Jamison, who has written extensively about her own manic depression, investigated the mental health of a group of British and Irish poets born between 1705 and 1805, including Byron, Shelley and Wordsworth. She concluded that poets were thirty times more likely to suffer from manic depression than the rest of the population, and five times more likely to commit suicide. She then interviewed nearly fifty successful, contemporary British writers and artists: more than a third had been treated for depression, and almost all reported wonderful creative outpourings whilst in their manic phase.
Nancy Andreasen came to similar conclusions in her fifteen-year study of the links between creativity and mental illness. While she found that writers were no more likely to suffer from drug addiction or schizophrenia than anyone else, she did find a link between writers and alcoholism (nine out of thirty, compared to only two out of thirty in the control group of non-writers). But it was in the area of manic depression that writers really came into their own. Out of the thirty writers Andreason studied, twenty four (that’s nearly four out of five) were manic depressives compared to only nine of the control group. During the course of the study, twenty writers needed treatment for manic depression, and thirteen suffered very severe manic episodes. Unfortunately, two of her subjects killed themselves before her research was concluded. You can guess which group they came from.