Parents of children with ADHD note that they usually display their symptoms at an early age. There have been few longitudinal studies on the long-term effects of stimulant use in children. The use of stimulant medication has not been approved by the FDA for children under the age of six. A growing trend is the diagnosis of younger children with ADHD. Prescriptions for children under the age of 5 rose nearly 50 percent from 2000 to 2003. Research on this issue has indicated that stimulant medication can help younger children with "severe ADHD symptoms" but typically at a lower dose than older children. It was also found that children at this age are more sensitive to side effects and should be closely monitored. Evidence suggests that careful assessment and highly individualized behavioural interventions significantly improve both social and academic skills, while medication only treats the symptoms of the disorder. "One of the primary reasons cited for the growing use of psychotropic interventions was that many physicians realize that psychological interventions are costly and difficult to sustain."