Pharmacological treatment of attention deficit hyperactivity disorder with co-morbid drug dependence

Background: Drug dependence is frequent in patients with attention deficit hyperactivity disorder (ADHD). Nevertheless, the efficacy and safety of pharmacological treatments in this population are unclear. Methods: A systematic review with meta-analysis was performed. Randomised placebo-controlled clinical trials investigating the efficacy of pharmacological treatment in patients with co-occurring ADHD and substance use disorder (SUD) were included. ADHD symptom severity, drug abstinence and all-cause treatment discontinuation were the primary study endpoints. The effects of patient-, intervention- and study-related covariates over the primary outcomes were investigated by means of meta-regression. Results: Thirteen studies were included, enrolling a total of 1,271 patients. A small to moderate reduction of ADHD symptoms was found. Meta-regression analysis identified the presence of a lead-in period as a covariate associated with reduced efficacy. Conversely, no beneficial effect was observed either on drug abstinence or treatment discontinuation. The efficacy on ADHD symptoms was smaller in studies with a lead-in period. A positive correlation between the efficacy for ADHD and that for SUD was found. Conclusions: The efficacy of pharmacological interventions for co-occurring ADHD and SUD has been little investigated. Mixed results were obtained: while pharmacological interventions improved ADHD symptoms, no beneficial effect on drug abstinence or on treatment discontinuation was noted. The strength of the recommendation of pharmacological treatment for co-occurring ADHD and SUD is therefore modest. The study was registered with the international prospective register of systematic reviews (PROSPERO): CRD 4212003414.