ADHD&me: Targeting Self-esteem in Youth With ADHD

The goal of this clinical trial is to learn whether the ADHD\&me (ADHD\&ik) intervention can improve self-esteem in youth aged 16-25 years with Attention Deficit Hyperactivity Disorder (ADHD). The ADHD\&me program is a cognitive behavioral therapy (CBT)-based intervention designed to help people with ADHD to develop a more positive view of themselves in their transition to adulthood. The main questions it aims to answer are: * Does the ADHD\&me intervention improve self-esteem in youth with ADHD, and are these effects maintained over time? * Does the intervention also improve related outcomes, such as masking of ADHD-related behaviors and co-occurring mental health symptoms including anxiety, depression, and stress? In this RCT, participants are assigned either to immediate treatment or to a waitlist control condition, with the latter receiving the intervention after an eight-week delay. Participants will: * Take part in seven individual therapy sessions according to the ADHD\&me intervention. * Complete questionnaires about self-esteem, masking of ADHD-related behaviors, ADHD symptoms, and co-ccurring mental health symptoms at several time points. * Complete short daily assessments (ecological momentary assessment) during one week at the start of the study and one week after the intervention or waitlist period to report momentary self-esteem, emotions, distress, and activities.