Background/Objectives: Adolescents with attention-deficit/hyperactivity disorder (ADHD) and bipolar spectrum disorders are at increased risk of substance use; categorical diagnoses may not fully explain individual variability in substance-related outcomes. This study examined substance use severity in clinically complex adolescents, focusing on the role of primary diagnosis and transdiagnostic dimensions (emotional dysregulation, impulsivity, cyclothymic-hypersensitive traits). Methods: In this…
