Yesterday the American Academy of Pediatrics issued new guidelines for treating attention deficit hyperactivity disorder, or ADHD, expanding the age range at which the condition can be diagnosed to include kids as young as 4 years old all the way up to young adults aged 18. The previous guidelines, made a decade ago, limited diagnoses to kids ages 6 to 12. The physician group decided to make the change due to new evidence that ADHD symptoms can surface in preschool-aged children and persist later into adolescence and adulthood than previously recognized. The report says methylphenidate (Ritalin) may help control ADHD symptoms in children ages 4 and 5, though only one large study has been done to support this conclusion. The authors stress, however, that medication should only be given after behavioral modifications are attempted—and that Ritalin may have some serious possible side effects like irreversibly slowing growth.