According to the latest data, a whopping 8 to 25 percent of kids are affected by chronic abdominal pain — or tummy aches — that don't have any particular root cause. And new research shows that this functional abdominal pain, as it's known in the medical world, in kids may be an indicator of anxiety disorders as kids grow into adults.

For the study, researchers at Vanderbilt University in Nashville, Tenn., tracked 332 children with chronic stomach pain that was not linked to any other condition, and compared them to 147 children who had never had such stomachaches. They found that roughly half of the participants who had experienced functional abdominal pain as kids developed an anxiety disorder later in life. The likelihood held firm even if the stomach pain had eventually cleared up although the link was definitely stronger when the pain persisted into adulthood. In the control group, 20 percent of participants had problems with anxiety. About 40 percent of the kids with stomach pain also experienced depression as adults compared to 16 percent of participants who did not have stomach issues.

So which comes first, the chicken or the egg? Are kids with stomach pain developing anxiety because of their lifelong tummy issues? Or is anxiety the underlying cause of the kids' pain? That's the big question that researchers need to figure out. In the meantime, this study suggests that parents of children who struggle with unexplained stomach pain might want to consider seeking counseling for their kids on the chance that anxiety is the root cause.

The study was published today in the journal Pediatrics.

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