The study, published in the February issue of the British Journal of Psychiatry, supports the belief that exceptional intellectual ability is associated with bipolar disorder.
Historical studies and anecdotal reports of famous and creative individuals suggest a link between high IQ and bipolar disorder – but until now, the scientific evidence for such a connection has been fairly weak. Researchers from the Institute of Psychiatry, King’s College London, teamed up with researchers at the Karolinska Institute in Sweden to investigate the association further.
All children in Sweden take compulsory exams at age 15-16, and the results are standardised nationally. The team used the Swedish national school register to obtain the grades of all students graduating from compulsory education between 1988 and 1997.
The researchers then used the Swedish hospital discharge register to test associations between the students’ academic achievement and admission to hospital with a diagnosis of bipolar disorder between the ages of 17 and 31. A total of 713,876 individuals were included in the study.
They found that students with excellent school performance were almost four times as likely to develop bipolar disorder as adults, compared to those with average grades. This increased risk remained after the researchers controlled for other factors such as parental education and socioeconomic status.
Students with the poorest grades were also at a moderately increased risk of bipolar disorder. They were almost twice as likely to develop bipolar compared to those with average grades.
Lead researcher Dr James MacCabe, Senior Lecturer at the Institute of Psychiatry, King’s College London, said: “We found that achieving an A grade is associated with increased risk for bipolar disorder, particularly in humanities and to a lesser extent in science subjects. A-grades in Swedish and Music had particularly strong associations, supporting the literature which consistently finds associations between linguistic and musical creativity and bipolar disorder.”
The researchers put forward several possible explanations for the link. First, people in a state of hypomania (a mild period of mania or elevated mood) can often be witty and inventive, and able to link ideas in innovative ways. Second, people with bipolar disorder often experience unusually strong emotional responses, which may help their talent in art, music and literature. Third, people with hypomania often have extraordinary stamina and can keep concentrating for long periods of time.
These types of cognitive style may help students perform better in creative school subjects – but also predispose them to bipolar disorder in later life.
Equally, the opposite of this mechanism may explain the link between poor school performance and bipolar disorder. Some people who go on to develop bipolar disorder, particularly those with depressive symptoms, may have cognitive styles that impair their academic performance. It is also possible that disturbed behaviour, substance misuse or undiagnosed depression may affect their studies.
The research also showed that the association between high grades and risk of later bipolar disorder appears to be stronger in males than females. But this association was not statistically significant and more research is needed to determine if the link is truly stronger in males.
Dr MacCabe concluded: “Our study suggests that getting A grades increases your chance of bipolar disorder – although we should remember that the majority of people with A grades enjoy good mental health.”
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MacCabe JH, Lambe MP, Cnattinguis S, Sham PC, David AS, Reichenberg A, Murray RM and Hultman CM (2010) Excellent school performance at age 16 and risk of adult bipolar disorder: national cohort study, British Journal of Psychiatry, 196: 109-115