Researchers at Washington University School of Medicine in St. Louis found that certain symptoms of conduct disorder indicate problems are likely to continue as kids reach school age. They recommend that children who exhibit these symptoms—among them, high-intensity defiant behavior, aggression and destruction of property—be referred to mental health professionals for evaluation and possible intervention.

"Previously, we did not understand the empirical differences between normal disruptive behaviors in preschoolers - like temper tantrums, for example—and behaviors that signal problems," said senior investigator Joan L. Luby, MD, professor of child psychiatry. "If you went to your pediatrician and said, 'My 3-year-old is having tantrums,' the pediatrician wouldn't tell you to see a psychiatrist."

Although there was overlap between healthy young children and their who had conduct disorder, the researchers found that those who exhibited high-intensity defiant behavior, aggression toward people or animals, high-intensity destruction of property, peer problems and deceitfulness, including stealing, were likely to have conduct disorder. Having those symptoms also made it more likely they would carry the disorder into elementary school.