Park 2013.

Methods	A cohort study of methylphenidate use for 2 weeks
Participants	Number of participants screened: not stated Number of participants included: 96 Number of participants followed up: 96 Number of withdrawals: 0 Diagnosis of ADHD: DSM‐IV‐TR (subtype: combined (62.5%), hyperactive‐impulsive (5.2%), inattentive (27.1%), NOS (5.2%)) Age: mean: 8.70 (SD 1.41) years old (range: 6‐12) IQ: not stated Sex: 79 males, 17 females Methylphenidate‐naïve: 100% Ethnicity: not stated Country: Korea Comorbidity: tic disorder: 10.4%, anxiety disorder: 8.3%, oppositional defiant disorder: 9.4%, enuresis: 6.3%, depression: 1.0% Co‐medication: no Sociodemographics: not stated Inclusion criteria: DSM‐IV‐TR diagnosis of ADHD Aged 6‐12 years ≥ moderate symptom severity on the Clinical Global Impression‐Severity (CGI‐S) scale and severe enough to warrant treatment with medication No previous exposure to psychostimulants Exclusion criteria: Other mental disorders, except for transient tic disorder, oppositional defiant disorder, mild anxiety disorder, and enuresis Current or previous brain damage or convulsive disorder Mental retardation, autism, language difficulties, or developmental problems, including learning disabilities
Interventions	Methylphenidate type: osmotic release oral system (OROS) methylphenidate Methylphenidate dosage: children weighing less than 30 kg were treated with 18 mg per day, and children weighing more than 30 kg were treated with 27 mg/day Administration schedule: not stated Duration of intervention: 2 weeks Treatment compliance: not stated
Outcomes	Barkley Symptom Rating Scale: a 17‐item list of methylphenidate‐related adverse event symptoms, rated from 0 (nothing) to 9 (severe) for symptoms during the past 2 weeks. Any negative sign, symptom, syndrome, or new illness that appeared or worsened after treatment began was counted as a treatment‐emergent adverse event
Notes	Sample calculation: no Ethics approval: approved by the institutional review board (IRB) for human subjects at the Seoul National University Hospital and other hospitals Funding/vested interests: the authors declare that there are no conflict of interest. The study was supported by a grant from the Korean Health Technology R&D Project, Ministry of Health & Welfare, Republic of Korea (A111523) and by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology, Republic of Korea (20110023888) Authors' affiliations: Seoul National University College of Medicine Key conclusions of the study authors: ADHD participants with the A/a genotype at the NTF3 rs6332 polymorphism showed the highest 'proneness to crying' and 'nail biting' item scores, followed by those with the G/a genotype and those with the G/G genotype (P = 0.047 and P = 0.017, respectively). These data provide preliminary evidence that genetic variation in the NTF3 gene is related to susceptibility to emotional side effects in response to methylphenidate treatment in Korean children with ADHD Exclusion of methylphenidate non‐responders/children who have previously experienced adverse events on methylphenidate: no