Tannock 1989.

Study characteristics
Methods	Within‐participant, cross‐over trial with 3 interventions: MPH 0.3 mg/kg MPH 1 mg/kg Placebo 2 different drug conditions each day
Participants	Number of participants screened: 16 Number of participants included: 12 Number of participants followed up: 12 (10 boys, 2 girls) Number of withdrawals: none Diagnosis of ADHD: DSM‐III ADD‐H (equivalent to 'combined' in later classifications) Age: mean 8.4 years (range 6‐11) IQ: mean 105 MPH‐naive: 5 received MPH previously. 3 were taking MPH at the time of referral and had a 48‐h pre‐trial washout Ethnicity: not stated Country: Canada Setting: outpatient clinic Comorbidity: ODD (n = 4), learning difficulties (n = 8; according to school record and defined as < 25th percentile on ≥ 1 subtests within the Wide Range Achievement Test (WRAT‐R)) Comedication: not stated Other sociodemographics: none Inclusion criteria Thought by referring physician to have ADHD Confirmed through assessment by 2 child psychiatrists using the PICS Questionnaire Confirmed by teacher information on Conners' Teacher Questionnaire, Rutter B Questionnaire and the Swanson, Nolan and Pelham Questionnaire Exclusion criteria Full‐scale WISC‐R < 80 Exclusive diagnosis of emotional or CD; major neurological, physical or sensory impairment; and/or any contraindication for use of MPH (e.g. tics, seizures, heart disease)
Interventions	Participants were randomly assigned to 1 of 3 possible drug condition orders of 0.3 mg/kg or 1.0 mg/kg MPH and placebo Mean MPH dosage: not stated. Administration schedule: interval of 4 h separated morning and afternoon doses Duration of each medication condition: not stated Washout before trial initiation: 4 h Titration period: none Treatment compliance: not stated
Outcomes	Non‐serious AEs Treatment‐emergent side effects (e.g. stomach distress, pallor, mood swings, tics) Pulse and BP readings taken in sitting position immediately before medication and again 1 h after administration of dose
Notes	Sample calculation: not stated Ethics approval: not stated Key conclusions of trial authors Behavioural and academic improvements produced by a dose of 0.3 mg/kg in the morning were no longer evident in the afternoon 1 mg/kg MPH produced behavioural improvements that were clinically and statistically discernible in the afternoon, although academic improvements had dissipated Carryover effects of MPH into the afternoon were discernible with 1.0 mg/kg but not with 0.3 mg/kg Comment from review authors Outcomes for ADHD symptoms were not appropriate for this trial, so only adverse effects were examined 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: Jointly funded by Ontario Mental Health Foundation (Grant Number 963‐86/88) and Health and Welfare Canada (Grant Number 6606‐3166‐42) Email correspondence with trial authors: sent email to trial authors to ask for additional information but have not received a reply.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"The order of medication condition was randomized with the restrictions that each child receive two different medication conditions each day (e.g. high, low) occur with equal frequency in the morning and afternoon" "The order of these six combinations was randomized for each child"
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"The methylphenidate and placebo were packaged in coloured gelatin capsules by the hospital pharmacist to avoid detection of dose and taste, packaged in individual envelopes and dispensed by project staff 1 hour before testing"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated
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