Serious mood disorders such as bipolar may be the price humans have had to pay for our intelligence and creativity.

That’s according to new research which links high childhood IQ to an increased risk of experiencing manic bipolar traits in later life.

Researchers examined data from a large birth cohort to identify the IQ of 1,881 individuals at age eight. These same individuals were then assessed for manic traits at the age of 22 or 23.

The statements they provided were part of a checklist widely used to diagnose bipolar disorder. Each person was given a score out of 100 related to how many manic traits they had previously experienced.

Individuals who scored in the top 10% of manic features had a childhood IQ almost 10 points higher than those who scored in the lowest 10%. This correlation appeared strongest for those with high verbal IQ.

“Our study offers a possible explanation for how bipolar disorder may have been selected through generations,” said Daniel Smith of the University of Glasgow , who led the study.

“There is something about the genetics underlying the disorder that are advantageous. 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.”



Smith emphasises that as things stand, having a high IQ is only an advantage: “A high IQ is not a clear-cut risk factor for bipolar, but perhaps the genes that confer intelligence can get expressed as illness in the context of other risk factors, such as exposure to maternal influenza in the womb or childhood sexual abuse.”



The results are consistent with previous research that suggests individuals with an increased genetic propensity to bipolar disorder were more likely to show a range of creative abilities, especially in areas where verbal proficiency may prove advantageous, such as in literature or leadership roles.

Bipolar disorder is thought to affect one in 100 people in the UK and is characterised by periods of depression followed by episodes of mania, during which people can feel extraordinarily happy, ambitious and creative. It can also include periods of psychosis.



Smith hopes the results, which were published today in the British Journal of Psychiatry, will help improve approaches for the earlier detection of the disorder. “I suspect there are things that can be done early on to help someone at high risk of bipolar, such as making certain lifestyle changes, protecting sleep patterns, avoiding certain stresses. The sooner we can intervene in bipolar the better the outcome,” he said.



Suzanne Hudson, chief executive of Bipolar UK, said “Given the rise in requests for support from parents and families of children to Bipolar UK, research that helps identify young people more at risk of developing bipolar disorder is vitally important.”

