Children with higher IQ may be prone to bipolar disorder in adulthood, says a new study.
The serious disorders of mood such as bipolar disorder may be a result of more adaptive traits such as intelligence, creativity and verbal proficiency. The research was published in the British Journal of Psychiatry
Scientists at the Universities of Glasgow, Bristol, Cardiff and Texas looked at the data from the Avon Longitudinal Study of Parents and Children (ALSPAC) for an association between measures of childhood IQ at age eight and lifetime manic features assessed at 22-23 years. They found that higher childhood IQ could indicate greater risk of bipolar disorder in adulthood.
"A possible link between bipolar disorder and intelligence and creativity has been discussed for many years and several studies have suggested a link. In this large study, we found that better performance on IQ tests at age eight predicted bipolar features in young adulthood," said Professor Daniel Smith of University of Glasgow.
"We are not saying that high childhood IQ is a clear-cut risk factor for bipolar disorder but rather that there is likely to be a shared biology between intelligence and bipolar disorder which needs to be understood more fully," said Smith.
Children had both verbal IQ (VIQ) and performance IQ assessed at age eight, to give a Full-Scale IQ measurement. The final results combining the data from 1,881 individuals showed a positive association between the two. Individuals who scored in the top 10% of manic features had a mean childhood IQ which was almost 10 points higher than those scoring in the lowest 10% of manic features. The association between IQ and manic features appeared to be strongest for verbal IQ (VIQ).
"Our finding has implications for understanding how liability to bipolar disorder may have been selected through generations. One possibility is that serious disorders of mood such as bipolar disorder are the price that human beings have had to pay for more adaptive traits such as intelligence, creativity and verbal proficiency," said Smith.
"This work will inform future genetic studies at the interface of intelligence, creativity and bipolar disorder, and will help with efforts to improve approaches to the earlier detection of bipolar disorder in adolescents and young adults," he added.
"The results of this study are very interesting. Studies of this kind are also important in the battle to tackle stigma," said Alison Cairns, Chief Executive of Bipolar Scotland.