People with bipolar disorder swing repeatedly from depression to euphoria and hyperactivity, or intensely irritable, mood states. Sometimes likened to being on an emotional rollercoaster, each swing up then down affects one's behaviour, energy levels, thought patterns and sleep. Also known as manic-depressive illness, bipolar disorder is strongly genetically linked, passing down through each generation of an affected family. It is fairly common and very treatable with modern medicines and psychotherapy.

A seminal work in the field is Kay Redfield Jamison's book Touched with Fire: Manic-depressive Illness and the Artistic Temperament. The American psychologist combined current diagnostic criteria with biographical data, diaries, family trees and other historical information to closely examine the lives of a sample of major 18th century British poets born between 1705 and 1805. Jamison found a rate of bipolar disorder 30 times greater in these poets than in the general population. Jamison's work also found that the periods psychiatrists call hypomania - mild but not full-blown mania - can also involve heightened creative thinking and expansiveness, high mental speed, cognitive flexibility, and ability to make original connections between otherwise disparate ideas, all elements underlying creativity.

Other studies by Jamison established that a number of speech components occur in individuals when hypomanic: they are more likely to use alliterations, to rhyme, to use idiosyncratic words, and engage in a playful use of language. When given drills, they can list synonyms or form word associations more rapidly than control groups. And so they rate highly on tests of creativity. Jamison's study of 47 eminent British writers and artists - selected on the basis of their having won at least one of several major prestigious prizes or awards in their fields - found 38 per cent of this group had been treated for a mood disorder, a category which includes depression as well as bipolar disorder.

Recent, large-scale studies provide additional scientific support to Jamison's work. A whole-population cohort study of all individuals in the Swedish national school register showed that those who demonstrated excellent school performances were nearly four times as likely to develop bipolar disorder as those who exhibited only average performance. Excellence in language or music was particularly correlated with an increased risk for developing bipolar disorder. Other studies have addressed a different pattern of association, one between creative occupation and mental illness. These studies found a clear over-representation of people with bipolar disorder (and their healthy siblings) in the most creative occupational categories, which included artists, musicians, writers and scientists.

While large, population-based studies provide us with the scientific rigour to test the link between bipolar disorder and creativity, some of the more interesting studies have involved smaller-scale, reflexive approaches. Here, writers and artists with personal experience of bipolar disorder have reflected on their own and their peers' creative processes, exploring how their mood states interact with their productivity.

In 2010, Stephanie Stone Horton reflexively traced her own and her colleagues' writing creativity and dysfunction as early career writers with bipolar disorder or depression. Horton described how hypomanic moods often facilitate writing periods characterised by fluency, flair and persuasive power, whereas the periods of mild depression or euthymia (even moods between the extremes) may be better used for editing and proofing. Olivia Sagan explored the experiences of mentally ill developing artists through longitudinal biographical interviews conducted with art students at two university sites. Narratives involved complex stories in which participants considered their illness to be part of themselves, albeit one that they needed to 'manage'.

One of the details of the narratives was the hypervigilance of health and ill-health on a continuum which at times threatened to jeopardise the dearly won achievement of becoming an art student. Here, participants often talked about the potentially productive, but also potentially destabilising, role of hypomanic moods.

Let us be clear. To argue for a link between bipolar disorder and creative achievement is not to argue that all, or even most, artists and writers automatically have a mental illness: indeed, most do not. To make such simplistic generalisations can reinforce the idea of the "mad genius" and trivialise a serious medical condition that can end in suicide. Yet the evidence to date suggests that a high number of artists and writers, far more than could be expected by chance, meet the diagnostic criteria for bipolar disorder.

What are the implications for treatment? First-line medication for bipolar disorder, lithium, can cause cognitive dulling and slowing, and limit emotional and perceptual range for some individuals. This is especially significant for those working in creative fields such as artists and writers, who draw on their emotions for creating their work. It is not surprising then that some artists and writers with bipolar disorder choose not to take medications. However, unless an individual has a mild expression of bipolar disorder, the consequences of the condition (suicide, for example) nearly always argue for active treatment. More research is need to understand not only how mood experiences interact with creative processes and artistic production, but to learn how mood episodes shape decisions about whether or not to accept treatment and if so, the treatment choices. We also need to learn more about how people with bipolar disorder can best be supported to make the most of their lives, with the highest degree of satisfaction in their achievements.

Society benefits from the achievements of its talented writers, artists and scientists with mental illness, yet those affected don't always judge their moments of brilliance to be worth the accompanying pain and distress, and don't always place their personal wellbeing and adherence to taking medication ahead of the potential to express their creativity.

Dr Claudia Slegers is a Research Fellow in the Michael Kirby Centre for Public Health and Human Rights at Monash University

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