Bipolar disorder
Bipolar disorder is a mood disorder characterized by periods of elevated mood known as mania or hypomania and periods of depression. Anecdotal and biographical evidence popularized the idea that sufferers of bipolar disorder are tormented geniuses that are uniquely equipped with high levels of creativity and superior intelligence. Bipolar disorder is relatively rare, affecting only 2.5% of the population, as it is also the case with especially high intelligence. The uncommon nature of the disorder and rarity of high IQ pose unique challenges in sourcing large enough samples that are required to conduct a rigorous analysis of the association between intelligence and bipolar disorder. Nevertheless, there has been much progress starting from the mid-90s, with several studies beginning to shed a light on this elusive relationship.