Children with behavioural problems are twice as likely to suffer chronic pain as adults than others, say researchers.

Scientists at Aberdeen University, who followed the lives of more than 19,000 children, think faulty hormone signals in the brain may play a key role.

Bad early life experiences may harm this brain system, causing both behavioural problems in childhood and chronic widespread pain in adulthood.

The findings, spanning 45 years, are published in the journal Rheumatology.

All of the children in the study were born in 1958, and mostly in the UK.

"It is becoming clear that events that happen early in childhood are important"

Dr John McBeth of Manchester University

Throughout the study, up until the age of 16, parents and teachers assessed the children’s behaviour looking for any "problem" signs such as poor ability to make friends, disobedience, stealing, thumb sucking and nail biting, lying, bullying and truanting.

When the children had grown up and reached the age of 42 they completed a questionnaire asking about psychological distress. At the age of 45 they completed another one about pain.

From this the researchers found that children with severe behavioural problems had double the risk of chronic widespread pain.

Dr Dong Pang, lead author of the work and a researcher at the University of Aberdeen, said: "We know already that severe adverse events in childhood such as hospitalisation after a road traffic accident and separation from mothers are linked to chronic widespread pain in adulthood."

But, until now, it was unknown whether maladjusted behaviour in children was a long-term marker for this type of pain.

"Our study shows that it is," he said.

Abnormal stress response

The researchers say that it is not just chronic widespread pain that is associated with bad behaviour in childhood.

Other adult problems associated with childhood behavioural problems include long-term psychiatric problems such as depression, anxiety and substance abuse.

They say that all these problems may be outcomes of the chain of events set in motion by the dysfunctioning "hypothalamic-pituitary-adrenal" or HPA axis – the system in the brain that controls hormones to help regulate the body’s response to stressful situations.

If further research proves this to be the case, then it might be possible to intervene in early life to prevent these problems occurring later.

Professor Gary Macfarlane, who also worked on the study, said changing a person’s lifestyle may help alter the pattern, including increasing the amount of exercise someone takes as well as watching out for signs of psychological distress and behavioural problems in childhood.

Dr John McBeth, a pain expert at Manchester University, said: "While the factors associated with developing chronic widespread pain are slowly being revealed, it is becoming clear that events that happen early in childhood are important.

He said the next challenge was to determine if problems with stress response system were operating in children.

"If the answer is yes, these studies offer exciting opportunities to develop early interventions to alleviate symptoms including chronic pain disorders in adulthood." </p

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