The brightest school children are also those most likely to suffer a serious mental illness as adults, research has shown.
Scientists found that pupils at the top of their class were four
times more likely to develop bipolar disorder than children with
average grades.
The condition is characterised by extreme mood swings alternating between depression and mania.
Previous research and anecdotal evidence from famous and creative
individuals have suggested a link between high IQ and bipolar disorder.
But until now, the scientific evidence for such an association has been
weak.
The new study looked at 713,876 individuals in Sweden, where all children take compulsory exams at the age of 15 and 16.
Hospital records and school reports were used to match academic
achievement with the chances of having bipolar disorder between the
ages of 17 and 31.
Students with excellent exam results had an almost four-fold greater
likelihood of being diagnosed with the condition than those whose
performance was average.
Children with the poorest grades were also more at risk, the
research showed. They were almost twice as likely to develop bipolar
disorder as average achievers.
The findings are reported today in the British Journal of Psychiatry.
Lead researcher Dr James MacCabe, from the Institute of Psychiatry
at 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 scientists suggest several possible explanations for the link.
They pointed out that people in elevated mood states can often be
witty and inventive, and able to link ideas in innovative ways.
People with bipolar disorder also tended to be highly emotional,
which may help their talent in art, music and literature. Thirdly,
people who are mildly manic often have extraordinary stamina and can
maintain concentration for long periods of time.
All of these traits might help students perform better in creative
school subjects, but also predispose them to bipolar disorder, said the
researchers.
But Dr MacCabe stressed that being clever at school did not usually lead to mental illness.
"Although having A grades increases your chances of bipolar disorder
in later life, we should remember that the majority of people with A
grades enjoy good mental health," he said.