Pliszka 2007.

Study characteristics
Methods	5‐week double‐blind, cross‐over, placebo‐controlled trial, conducted to examine electrophysiological effects of MPH on inhibitory control in children with ADHD MPH Placebo
Participants	Number of participants screened: 12 Number of participants included: 12 (8 boys, 4 girls) Number of participants followed up: 12 Number of withdrawals: 0 Diagnosis of ADHD: DSM‐IV (combined (100%)) Age: mean 12.3 years (range 9‐15) IQ: not stated MPH‐naive: 10 Ethnicity: white (67%), African American (8%), Hispanic (25%) Country: USA Setting: not stated Comorbidity: ODD (45%) Comedication: not stated Other sociodemographics: none Inclusion criteria ADHD, combined type CGI: restless/impulsive ratings ≥ 1.5 SD above the mean for child’s age and sex on both parent and teacher ratings Exclusion criteria General Cognitive Ability on DIfferential Abilities Scale > 85 Any substance abuse/dependence Any neurological disease Long‐term use of any medicine Learning disability
Interventions	Participants were randomly assigned to different possible drug condition orders of 5 mg, 10 mg, 15 mg, 20 mg MPH and placebo Mean MPH dosage: not stated Administration schedule: 3 time points Duration of each medication condition: 7 days Washout before trial initiation: not stated Medication‐free period between interventions: 0 Titration period: none initiated before/after randomisation
Outcomes	General behaviour Parents and Teacher CGI
Notes	Sample calculation: no Ethics approval: yes; trial approved by the Institutional Review Board of the University Comments from trial authors "Several limitations of the study should be noted Our sample was relatively small and was composed entirely of children with ADHD, combined type alone, and no other significant comorbidity other than ODD" All participants were positive responders to MPH Our sample was too small to examine for effects of sex and ethnicity, and results should be replicated in a larger sample" Key conclusions of trial authors MPH may improve inhibitory control by enhancing brain mechanisms that trigger the inhibitory process and make stopping a motor act more probable (reflected by increased N200) and by increasing attentional resources to the task when unsuccessful inhibitions occur (as reflected by increased NoGo‐P3) These results are consistent with functional imaging studies, suggesting a role for the right frontal inferior cortex and the cingulate cortex in the pathophysiology of ADHD Comment from review authors Although this study includes only good responders to MPH, this occurred by chance and not by design, as 10 out of 12 were treatment‐naive Exclusion of MPH non‐responders/children who have previously experienced AEs while taking MPH before randomisation: no Any withdrawals due to AEs: no Funding source: NIMH Grant R01 MH63986 Email correspondence with trial authors: May 2014. Trial authors could not give us the necessary data (e.g. separate data for each intervention period); therefore we could not use CGI data
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: insufficient information regarding generation of random sequence allocation to permit a judgement of low or high risk of bias.
Allocation concealment (selection bias)	Unclear risk	From email: "one investigator was assigned on the basis of chance; the other remained blinded"
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Double‐blind. One investigator assigned on the basis of chance; the other remained blinded
Blinding of outcome assessment (detection bias) All outcomes	Low risk	One investigator assigned on the basis of chance; the other remained blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	No dropouts Selection bias (e.g. titration after randomisation → exclusion): no
Selective reporting (reporting bias)	Unclear risk	No protocol identified