Douglas 1995.

Study characteristics
Methods	8‐day, double‐blind, cross‐over trial in which participants were randomly assigned to different doses of MPH and placebo: 0.3 mg/kg MPH 0.6 mg/kg MPH 0.9 mg/kg MPH placebo Phases Assessment week 1: 4 different doses given on 4 different days Assessment week 2: same structure as assessment week 1
Participants	Number of participants screened: not stated Number of participants included: 17 (16 boys, 1 girl) Number of participants followed up: not stated Number of withdrawals: not stated Diagnosis of ADHD: DSM‐III‐R. Also had to meet DSM‐III criteria for ADD‐H Age: mean 9 years 5 months (range 6 years 3 months‐11 years 9 months) IQ: mean 104.3 (range 89.0‐127) MPH‐naive: 53% Ethnicity: not stated Country: Canada Setting: treatment centre (hospital) or outpatient clinic Comorbidity: ODD (71%), CD (18%) Comedication: not stated Other sociodemographics: none Inclusion criteria DMS‐III‐R criteria for ADHD DSM‐III criteria for attention deficit disorder with hyperactivity Ratings from both mothers and teachers at or above a criterion score of 1.5 on the Hyperactivity Index of the Revised CRS Exclusion criteria IQ < 85 Serious visual, auditory or speech deficits Evidence of organic damage Evidence suggesting that symptoms could be attributed to emotional problems or a stressful home environment
Interventions	Participants were randomly assigned to 1 of 24 possible drug condition orders of MPH (0.3 mg/kg, 0.6 mg/kg, 0.9 mg/kg) and placebo Mean MPH dosage: 0.3 mg/kg: 9.71; 0.6 mg/kg: 19.42; 0.9 mg/kg: 29.14 Administration schedule: once daily Duration of each medication condition: 1 day; each child received each dosage twice during the trial (i.e. during first and second assessment weeks) Washout before trial initiation: in the case of children currently receiving stimulants, medication was discontinued ≥ 48 h before screening Titration period: none Treatment compliance: to ensure compliance, medications were administered at the laboratory
Outcomes	Non‐serious AEs Not described as a measure for the trial, but the Barkley Side Effects Rating Scale is mentioned
Notes	Sample calculation: no information Ethics approval: no information Key conclusion of trial authors Under acute dosage conditions as used in this trial, MPH doses up to 0.9 mg/kg had an increasingly positive effect on measures of mental flexibility and other cognitive processes 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: grants from the Medical Research Council of Canada and by William T. Grant Foundation Faculty Scholar Program Email correspondence with trial authors: October 2013. Emailed last trial author twice to get supplemental information (protocol, ethics approval, data on side effects, etc.) but received no response. Therefore we included no data from this trial
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Drug order was determined by consecutive assignment to a randomly ordered list of 24 possible combinations of 4 medication levels for each of the 2 testing weeks
Allocation concealment (selection bias)	Low risk	Drug order was determined by consecutive assignment to a randomly ordered list of 24 possible combinations of 4 medication levels for each of the 2 testing weeks. To maximise blindness of examiners, all participants received a different drug order for assessment weeks 1 and 2
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Medications containing active drug and placebo were prepared in identical opaque gelatin capsules and were administered in a double‐blind fashion
Blinding of outcome assessment (detection bias) All outcomes	Low risk	To maximise blindness of examiners, all participants received a different drug order during assessment weeks 1 and 2
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Not stated whether any participants were LTFU Selection bias (e.g. titration after randomisation → exclusion of MPH non‐responders or placebo responders): no
Selective reporting (reporting bias)	Unclear risk	No protocol identified