EUCTR2020‐003660‐11‐NL.

Study name	Public title: Methylphenidate long‐term study Scientific title: Do effects of methylphenidate decline after long‐term use? A double‐blind, placebo‐controlled cross‐over study of effects of methylphenidate on cognitive functioning and real world behavior in treatment naive children compared to effects after 9 months of treatment in clinical practice
Methods	Randomized, double‐blind, placebo‐controlled cross‐over trial Study duration: 3 years
Participants	Sample size (target): 60 Inclusion criteria Children between the ages of 6 and 12, any ethnicity or cultural background Diagnosed with ADHD as confirmed with the PICS (obtained during routine clinical assessment) Going to start MPH as per clinical decision No use of MPH for the past 6 months Bodyweight of at least 20 kg Deemed reliable and compliant with the protocol parents (or the legal guardian) and children (12 years) have provided informed consent to participate in the study Exclusion criteria Intellectual disability (based on available IQ < 70 or the clinical opinion of the investigator, taking into account relevant psychosocial information, e.g. educational level/academic achievements; or as confirmed by the IDS‐2 IQ screener obtained in each participant)
Interventions	MPH 10 mg Placebo
Outcomes	General behaviour ADHD‐related behaviour (measurement scale not reported) Assessed at baseline, week 2 and week 40
Starting date	21 December 2020 (entered into trial registry). Start date not reported
Contact information	Name: Andrea Dietrich Affiliation: Accare, Lübeckweg 2, Groningen, 9723 HE, Netherlands Telephone: + 310613807225
Notes	Sponsor: Accare Declaration of interest: not reported