Study designs of evaluations included in the review
Comparative studies with at least 10 children in the intervention and control group were eligible for inclusion.
Specific interventions included in the review
Studies comparing immediate-release methylphenidate with placebo were eligible for inclusion. The majority of the included studies used a single dose immediate-release methylphenidate that was not varied based on patient characteristics.
Participants included in the review
Studies of children who met formal diagnostic criteria for ADHD or attention-deficit disorder, or who were described as hyperactive or hyperkinetic, were eligible for inclusion. Studies were excluded if all the participants had a single co-morbid disorder. The age range of the children in most of the included studies was 6 to 12 years, though some studies included older children. The clinical population appeared to vary between studies. Participants had ADHD, ADHD combined type or ADHD inattentive type. The prevalence of co-morbid disorders ranged from 40 to 90% and included conditions associated with cognitive impairment independent of ADHD.
Outcomes assessed in the review
Studies assessing performance on cognitive tasks were eligible for inclusion. A wide variety of cognitive measures were used across the included studies.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.