08/13/2013 01:32 EDT | Updated 10/13/2013 05:12 EDT

Stomach aches in children tied to anxiety in adulthood

Children with chronic, unexplained stomach pains may be at high risk for anxiety disorders later in life even if the abdominal pain goes away, new U.S. research suggests.

It's estimated that chronic abdominal pain affects between eight and 25 per cent of school-age children who often miss class. Now researchers show an association between "functional abdominal pain" that has no medical explanation and anxiety that persists into adulthood.

Of the adults who had abdominal pain as children, 51 per cent had an anxiety disorder during their lifetime compared with 20 per cent of adults in a control group who had an anxiety disorder in their lifetime.

"This is the first study of pediatric functional abdominal pain to integrate mental health and abdominal pain outcomes," Lynn Walker, a pediatrics professor at Vanderbilt University in Nashville, and her co-authors concluded in this week's issue of the journal Pediatrics.

"Patients with functional abdominal pain carry long-term vulnerability to anxiety that begins in childhood and persists into late adolescence and early adulthood, even if abdominal pain resolves."

The risk was highest if the abdominal pain persisted.

Forty per cent of adults who had abdominal pain as children had depression during their lifetime, compared with 16 per cent of adults in the control group.

The study included 332 children with unexplained stomach pain and 146 children who were controls. They were all between the ages of eight and 17 when the study began. Participants were followed for an average of 20 years.

While stomach pain was associated with anxiety and depression in adulthood, no cause-and-effect relationships were shown.

It's also not clear how the two conditions are linked. The researchers speculated anxiety related to pain or social anxiety disorder that contributes to missing school could perpetuate disability from pain.

Dr. Rose Geist of the psychiatry and pediatric departments at Toronto's SickKids Hospital co-authored an earlier paper with Walker on medically unexplained symptoms in young people.

In the paper, Geist suggested a rehabilitative approach that discourages a focus on relieving symptoms and instead encourages the patient to return to usual activities and responsibilities.