(WXYZ) - A new study suggests kids' tummy troubles may be linked to anxiety disorders later in life. Researchers at Vanderbilt University studied more than 400 children and followed them throughout early adulthood. Adults who reported having chronic stomachaches, or functional abdominal pain, as children were more likely to experience anxiety and depression. According to the study, functional abdominal pain is recurring stomachaches that cannot be explained by a physical cause. Researchers found 51 percent of adults who had frequent stomachaches as children suffered from an anxiety disorder as an adult in the past and 40 percent also suffered from depression. Nearly one third of adults who had functional abdominal pain as children were still struggling with an anxiety disorder. Researchers say stress and anxiety can cause stomachaches in children, and stomachaches could be a key warning sign that a child does not know how to cope with stress. If your child suffers from chronic stomachaches, researchers recommend talking with him or her about stress-reducing techniques or having a medical professional administer a mental health checkup.