International Study to Predict Optimised Treatment in Children and Adolescents with Attention Deficit/Hyperactivity Disorder

This study is looking at what brain, thinking, and genetic patterns are linked to ADHD in children and teenagers. It also aims to find out which of these patterns can predict how well a child will respond to methylphenidate (a common ADHD medication like Ritalin). Understanding these patterns could help doctors choose the best treatment for each child more quickly. You may be eligible if: - Your child is between 6 and 17 years old - Your child has been diagnosed with ADHD according to standard medical guidelines (DSM-IV) - Your child scores above the threshold on the standard ADHD rating scale - Your child is a candidate for methylphenidate treatment - Your child has never taken methylphenidate or other stimulant medications before (or has not taken them recently) - Your child is fluent in English or Dutch You may NOT be eligible if: - Your child has previously taken or is currently taking methylphenidate or other stimulant medication - Your child has had a brain injury causing loss of consciousness - Your child has severe difficulties with vision, hearing, or hand movement that would prevent completing the tests Talk to your doctor about whether this trial might be right for you.