People with bipolar disorder, or manic depression, suffer severe and uncontrollable mood swings from elation to depression. During their elation (manic) periods they may have insomnia, restlessness, racing thoughts, and may have an over-inflated self-esteem. In the depressed stages they may be suicidal. Around 1% of the population suffers from bipolar disorder.

The national cohort study was carried out by scientists from King’s College London's Institute of Psychiatry and the Karolinska Institute in Stockholm, Sweden. The team, led by King’s College senior lecturer in psychiatric epidemiology, Dr James MacCabe, studied the final exam results of all 15-16-year-old pupils attending High Schools in Sweden from 1988 to 1997, and compared them to hospital records of bipolar disorder admissions of patients between the ages of 17 and 31.

They found those with A-grade results were almost four times more likely to be admitted for the condition than average students, even after the findings were controlled for income and education level of the parents. The link was stronger in males than females. They also found students with low exam grades had a greater risk of developing bipolar disorder than average pupils.

The researchers found the highest rate of bipolar disorder developed in those who excelled in the humanities, such as literature or music, which are the two subjects traditionally most associated with “madness”. For example, the artist Van Gogh, poet Sylvia Plath, and writer Virginia Woolf, are widely believed to have had bipolar disorder.

The findings of a link between the disorder and academic and intellectual performance may explain the association between genius and mania that has long been thought to exist. People with bipolar disorder who are in a manic phase can have exaggerated emotional responses and can be witty, inventive and have high cognitive capabilities. They are also capable of sustained concentration and have high stamina, and so can achieve much more than people without the disorder.

Since low achievers, especially those poor at handicrafts and sport, also had an increased risk, the scientists suggest there are two distinct groups of people with bipolar disorder: the high achievers who are aided by their manic stages, and low achievers who have poor motor skills, which may be caused by "subtle neurodevelopmental abnormalities".

The paper is published in the British Journal of Psychiatry 196: 109-115.