Attention-deficit hyperactivity disorder (ADHD) is characterised by age-inappropriate and impairing levels of inattention, hyperactivity, or impulsivity, or a combination.1 It is estimated to affect around 5% of school-age children (aged ≤18 years)2 and 2·5% of adults worldwide.3 Annual incremental costs for ADHD have been estimated at US$143–266 billion in the USA4 and are substantial in other countries.5, 6 Available pharmacological treatments for ADHD include psychostimulants (eg, methylphenidate and amphetamines) and non-psychostimulant medications (eg, atomoxetine and α2-agonists). In the past few decades, prescriptions for ADHD drugs have increased significantly both in the USA7 and other countries.8 However, even though recommended in clinical guidelines,9, 10, 11, 12, 13, 14 the efficacy and safety of ADHD medications remains controversial.15, 16, 17 Furthermore, current guidelines are inconsistent in their treatment recommendations.9, 10, 11, 12, 13, 14 Although some guidelines rank methylphenidate over amphetamines (eg, in children),9 others recommend psychostimulants as first-line treatment without any distinction between methylphenidate and amphetamines being made.10, 11 Additionally, the non-psychostimulant atomoxetine is variously recommended by available guidelines as third-line,9 second-line,10, 11 and potentially first-line treatment.12 The methods used for
