The potential association of creativity with mental illness has generated both scientific interest and controversy since such a relationship was first posited by the ancient Greeks.
The two might interact in a variety of ways. Both might share similar predisposing factors, yet not be causally related to each other. Or the creative effort might be psychologically taxing to the point of causing psychopathology. Or psychopathologic symptoms (such as bizarre associations, hallucinations, or feelings of grandiosity and boundless energy) might promote creativity.
And it may be that any of these relationships can be true in some people and not in others. Not every possible relationship has been addressed by every study, so that the findings of one study may not address questions raised by another.
As with any scientific question, the most important first step is to establish the validity of the observation: Is there a greater-than-expected level of mental illness among creative people? But even this question is more complex than it might first seem. What do we mean by "creative people"? Creativity is not a unique skill possessed solely by the fortunate few, but a general mode of human thought characterized by motivation, perception, mental imagery, strategic formulation, dexterous execution, temperament, and social context. These principles are the same whether we are trying to avoid a traffic jam, diagnose a patient, or write a poem. We are all, in this way, creative people, but studies addressing this question generally focus on those in more traditionally regarded creative occupations, such as art and music.
In the United States in 2001-2003, 30% of the population experienced some form of mental illness (N. Engl. J. Med. 2005;352:2515-23). Evidence of higher prevalence rates among the more creative comes from biographical and survey studies (typically of eminent people), family studies (via relatives of psychiatric patients), psychiatric patients themselves, correlations among the general public of scores on tests for psychopathology and tests of creativity, and the psychometric assessment of individuals in creative pursuits (J. Res. Person. 2005 Oct. 270 [doi:10.1016/j.jrp.2005.09.004]).
Absolutes rates differ among studies, but many have shown an elevated prevalence of depression among writers (Am. J. Psychiatry 1987;144:1288-92; Br. J. Psychiatry 1994;165:22-34). In Arnold Ludwig’s biographical study of 1,005 individuals whose biographies were published in the New York Times Book Review over a 30-year period, depression, suicide attempts, psychosis, and forced hospitalization were prevalent in more than 60%, 20%, 17%, and 11.3%, respectively, of poets older than age 40 (Am. J. Psychother. 1992;46:330-56).
Other groups fared a bit better, although suicide rates were also relatively high in members of the theatre and in musical performers. Overall, alcoholism and depression were the most common problems among the creative professions. Compared with the nonartistic professions (such as politics or physical science), artists (including writers, painters, musicians, and actors) had higher rates of all forms of psychopathology and psychiatric interventions. Total lifetime depression and anxiety scores correlated with overall level of creative achievement in all professions, but the relationship was weak (R2 = 0.04).
Although depression and substance abuse are more prevalent among those in the artistic professions (and writers in particular), it is less clear that this represents a causal relationship. Hypomania may enhance self-confidence and the formation of associations, and may focus goal-directed activity, all of which can foster creativity, but full-blown manic psychosis (or psychosis for any other reason) disrupts rational thought and is not conducive to creativity. Depression saps motivation and thus inhibits creativity.
Patients who are actively psychotic are unable to be creatively productive, but schizophrenic patients who are between psychotic episodes share some creativity-associated traits (such as divergent thinking) with their first-degree relatives and those in the artistically creative professions. This has led some to argue that schizophrenia itself may promote creativity, hence its prevalence and persistence in the human gene pool.
There is indirect neurobiological evidence that supports this claim. Normally, the default network (which includes medial prefrontal, posterior cingulate, and lateral parietal cortices) is active at rest. It is also active during daydreaming and internally generated, task-independent mentation – that is, mental states that foster creative ideas. External sensory stimuli to which we attend result in suppression of the default system activity, and greater suppression is associated with better performance on attention-demanding tasks. In schizophrenic patients, there is reduced suppression of the medial prefrontal component of the default system, which reflects their poor attentional skills. There is also increased connectivity between default regions and the rest of the brain, and this is also thought to promote creativity by facilitating unusual associations and even synesthesia. Among healthy people, reduced suppression is associated with mind wandering, a mental state that predisposes to "aha" moments that characterize some creative activity. These neurophysiological alterations correlate with personality variations, not only in schizophrenic patients but also in their first-degree relatives and "creative controls" (Proc. Natl. Acad. Sci. U.S.A. 2009;106:1279-84).