We used several strategies, outlined through the Preferred Reporting Items for Systematic Reviews and Meta-Analyses flowchart (eFigure; http://www.jamapsych.com), to identify the 15 studies included in this meta-analysis. First, we conducted computer-based searches using PubMed according to the following keywords (or stems when possible): alcohol, nicotine, smoking, tobacco, cigarette, marijuana, cannabis, cocaine, substance(s), drug(s), ADHD, ADD, attention-deficit, attentiondeficit/hyperactivity disorder, hyperactivity, hyperactive, hyperkinetic, stimulant, methylphenidate, pharmacotherapy, medication, longitudinal, and prospective. Keywords were combined byusing the Boolean operators “AND” and “OR.” Second, we expanded our search through the ancestry approach in which potential studies were identified from the reference sections of relevant studies and reviews pertaining to stimulant treatment and substance disorders. Third, we reviewed the bibliographies for additional studies using forward and backward searching. To combat the file drawer problem, we attempted to locate unpublished studies by sending e-mails describing our study and its inclusion criteria to professional membership listservs of research organizations, including Division 53 of the American Psychological Association and the International Society for Research in Child and Adolescent Psychopathology, and to authors who have published longitudinal studies of children
