Walitza 2009.

Methods	A prospective study (both cohort study: the drug naïve group, and cross‐sectional study: the chronically treated group) analysing genomic damage in 3 different group of children: Healthy control group ADHD and chronically methylphenidate‐treated (more than 12 months) group Drug naïve group of ADHD affected children who initiated methylphenidate treatment
Participants	Drug‐naïve group Number of participants screened: not stated Number of participants included: 26 Number of participants followed up: 3 months: 17, 6 months: 11 Number of withdrawals: 3 months: 9, 6 months: 15 Diagnosis of ADHD: DSM‐IV (subtype: not stated) Age: mean 8.6 years old (range 5‐16) IQ: above 70 Sex: 20 males, 6 females Methylphenidate‐naïve: 100% Ethnicity: not stated Country: Germany Comorbidity: not stated Comedication: not stated Sociodemographics: not stated Chronically methylphenidate‐treated group Number of participants screened: not stated Number of participants included: 21 Number of participants followed up: not stated Number of withdrawals: not stated Diagnosis of ADHD: DSM‐IV (subtype: not stated) Age: mean: 11.4 years old (range 9‐16) IQ: above 70 Sex: 16 males, 5 females Methylphenidate‐naïve: none. All but 1 treated more than 12 months with methylphenidate Ethnicity: not stated Country: Germany Comorbidity: yes, but not specified Comedication: 4. 1 also took atomoxetine, 1 sulthiame, and 2 risperidone Sociodemographics: not stated Both groups Inclusion criteria: DSM‐IV‐TR diagnosis of ADHD Drug naïve group: drug naïve Chronically treated group: methylphenidate treatment more than 12 months (1 patient only treated the past 10 months) Exclusion criteria: Current smoking Current infection or an infection in the last 14 days before blood sampling Extreme food patterns (e.g. vegans) Psychiatric diagnosis, such as: anorexia nervosa, schizophrenia, any pervasive developmental disorders, neurological disorders such as epilepsy, a history of any acquired brain damage or evidence of fetal alcohol syndrome
Interventions	Methylphenidate type: not stated Mean methylphenidate dosage: after 3 months: 0.46 (SD 0.22) mg/kg/day. After 6 months: 0.46 (SD 0.24) mg/kg/day. Chronically treated group: 0.80 (SD 0.31) mg/kg/day Administration schedule: not stated Duration of intervention: 6 months Treatment compliance: not stated
Outcomes	Non‐serious adverse events Vital signs, blood pressure, pulse, ECG Blood test to detect haematological abnormality. Micronucleus analysis (measure of genomic damage): blood sampling and sampling of buccal mucosa cells: baseline, 3, and 12 months after initiation of treatment. Only 1 blood sample/buccal mucosa sample at a certain point of time for the chronic group
Notes	Sample calculation: not stated Ethics approval: approved by the ethics committee of the University of Würzburg (study no. 124/06) Funding/vested interest: this study (124/06) was funded by grants from the IZKF Wuerzburg (Interdisciplinary Clinical Center of the University of Wuerzburg), project N5‐1, and supported by a grant from the Deutsche Forschungsgemeinschaft (KFO 125) Authors' affiliations: during the course of this study, HS was asked to serve as an independent consultant for Novartis Pharmaceutical Company. Consulting occurred after this study was finished (all data evaluated) and did not influence any aspect of this study. The other authors declare no potential conflicts of interest Key conclusions of the study authors: in this study, we did not find any alteration in the number of micronucleated cells in the group of chronically treated (> 12 months) children compared to the ADHD group before treatment initiation. We also did not find any elevation after initiation of methylphenidate treatment at 2 follow‐up intervals at 3 and 6 months after treatment initiation. This is the result from both investigated tissues, peripheral blood lymphocytes and buccal mucosa cells. Therefore, no induction of genomic damage in ADHD patients due to methylphenidate therapy was detectable, supporting our previous study (124/06) Exclusion of methylphenidate non‐responders/children who have previously experienced adverse events on methylphenidate: 2 withdraw after 1 month of treatment due to lack of effect Supplemental information regarding the children's intellectual function received through personal email correspondence with the authors in October 2013 (Stopper 2013 [pers comm]), and mean and SD on measure of genomic damage received in March 2014 (Stopper 2014b [pers comm])