Editorial: Stimulant-Evoked Neural Trajectories Reveal Distinct Neurobiological Phenotypes for Attention-Deficit/Hyperactivity Disorder Based on Familial Risk.

Some of the greatest challenges in understanding and treating attention-deficit/hyperactivity disorder (ADHD) stem from its heterogeneity and high rates of comorbidity.1 In particular, disentangling ADHD from early symptoms of bipolar disorder has been a long-standing challenge for the field of child psychiatry.2 This issue is particularly thorny because of concerns about treatment-emergent mania when treating ADHD with psychostimulant medication in youth with comorbid bipolar disorder,3 and possibly even in those at familial risk for bipolar disorder.4 In this context, the field stands in need of reliable biomarkers to guide treatment selection. Advances in this area will require a better understanding of how neural circuits vary across different subtypes of clinical disorders and, in particular, how interventions might affect these circuits differently across subtypes. In this issue of the Journal, Qin and Pan et al.5 address this knowledge gap by comparing how the brain changes after psychostimulant treatment in ADHD youth with vs without familial risk for bipolar disorder.