Many children use ADHD medication for an extended period. Medication typically works well at the beginning of treatment. However, it is not well understood whether medication continues to be effective in the long term and its impact on the brain. There are indications that tolerance to the medication may develop after prolonged use. We aim to investigate the long-term effects of ADHD medication in children, adolescents, and young adults with ADHD, utilizing brain scans and computer tasks. Additionally, we will examine the effects of the medication on the brains of rats of varying ages. This research will provide insights into how the brain responds to prolonged use of ADHD medication, ultimately contributing to the improvement of ADHD medication usage in the future.