Past Issues

Background: Attention‑deficit hyperactivity disorder (ADHD) is the most commonly diagnosed neurodevelopmental disorder known to cause impairment across the lifespan. ADHD was ranked as approximately the 50th leading cause of global years lived with disability for children, coming in ahead of diabetes, meningitis, and intellectual disability. About 20%–40% of patients with ADHD would not achieve the treatment response and symptomatic remission, increasing future risks of substance abuse, suicidal behavior, and premature mortality. However, there is no standard consensus for defining treatment resistance in ADHD. Method: In this systematic review, we intend to focus on treatment‑resistant ADHD in the aspects of disease definition, psychopathology, pathophysiology, and treatment. Results: We suggest that the more ideal strategy of defining treatment resistance should consider the improvement of ADHD symptoms and the global functioning simultaneously. Psychiatric comorbidities (i.e. destructive behavior disorders and mood disorders), physical comorbidities (i.e. epilepsy), and psychosocial adversities (i.e. parental psychopathology and poor family functioning) should be the first to be assessed in the evaluation of treatment response or resistance. The optimal medication adjustment or the combination of medications and psychotherapy may be the potential therapeutic strategy for treatment‑resistant ADHD. Conclusion: Further studies would be necessary to elucidate the underlying mechanisms of treatment‑resistant ADHD and to research the novel treatment strategies for ADHD.