Introduction
Psychiatric, hyperactivity, Attention-deficit/hyperactivity disorder, impulsivity, ADHD
Attention-deficit/hyperactivity disorder (ADHD) is characterised by developmentally inappropriate levels of hyperactivity, impulsivity, and/or inattention (American Psychiatric Association Functional magnetic resonance imaging (fMRI) studies of working memory in youth with ADHD relative to neurotypical individuals show consistent increases in fronto-parietal coupling (Massat et al. The catecholamine transporter blocker methylphenidate (Wilens Also, methylphenidate has shown to normalise functional connectivity differences between boys with ADHD and neurotypical controls in executive control, fronto-parietal, and auditory networks, and to increase the connectivity within the executive control network compared to placebo (Wu et al. Consequently, the aim of this pseudo-randomised, double-blind, placebo-controlled, cross-over fMRI study was to test the comparative effects of single doses of methylphenidate and atomoxetine relative to placebo on functional networks involved in working memory in medication-naïve boys with ADHD, and to test for potential normalisation effects of the two drugs on brain connectivity differences during placebo relative to unmedicated age-matched neurotypical controls. This study extends a previously published analysis of shared and distinct effects of the two drugs on brain activation during working memory in the same cohort (Cubillo et al. In line with previous reports of fronto-parietal hyperconnectivity during working memory (Massat et al. 