This Section of Epidemiology and Psychiatric Sciences appears in each issue of the Journal to stress the role of the epidemiological approach to promote advances in the field of clinical psychopharmacology, with a particular attention to controversial findings. The ultimate aims are to help develop a more critical attitude towards the results of research studies published in the international literature, to promote original research projects with higher methodological standards, and to implement the most relevant results of research in every-day clinical practice. These contributions are written in house by the journal's editorial team or commissioned by the Section Editor (no more than 1000 words, short unstructured abstract, four key-words, one Psychostimulants are the first choice medication in children with attention-deficit/hyperactivity disorder (ADHD). Despite the proven high efficacy of psychostimulants, at least in the short term, for ADHD core symptoms, concerns continue to be raised on their adverse effects, including putative increased risk of substance use disorders (SUDs). A recent multicentre, case-control, longitudinal, prospective, European study by Groenman and colleagues found that treatment with psychostimulants in children with ADHD lowered the risk of SUDs in adolescence. However, this finding is at odds with other recent evidence concluding that ADHD children with and without medication treatment history did not significantly differ on any subsequent SUDs rates. In the present paper, we discuss the study by Groenman and colleagues in view of its methodological strengths and limitations, and we suggest possible implications for dayto-day clinical practice. Psychostimulants (including methylphenidate and amphetamines) are indicated by several guidelines (e.g., Pliszka, 2007; NICE, 2008) as first choice medication for children with attention-deficit/hyperactivity disorder (ADHD). Whereas a large body of randomised controlled trials supports the high efficacy of psychostimulants on ADHD core symptoms (at least in the short-term), concerns continue to be raised regarding their adverse effects, including possible increased risk of substance use disorders (SUDs) (Cortese et al. 2013).To address the effects of psychostimulant treatment in childhood on later risk for SUDs, Groenman et al. (2013) analysed data from the International Multicenter ADHD Genetics study (IMAGE), a multi-site longitudinal, prospective study including probands with ADHD and healthy controls (HC). The authors assessed the relation between exposure to psychostimulants in childhood (age range: 5-17 years) and rates of SUDs (including nicotine dependence) at follow-up, on average 4.4 (±0.7) years after study entry. Baseline assessment included categorical measures of ADHD, oppositional defiant disorder (ODD) and conduct disorder (CD), as well as measures of ADHD symptoms severity. At follow-up, analysable * Address for correspondence: Dr Marianna Purgato, Department of Public Health and Community Medicine, Section of Psychiatr...