{"p"=>" Disruptive mood dysregulation disorder (DMDD) was introduced in DSM-5 in 2013 to address concerns about overdiagnosis of pediatric bipolar disorder in chronically irritable children. We examined population-level trends in DMDD and bipolar disorder diagnoses and psychotropic medication use in youth. We conducted an interrupted time-series analysis using electronic health record data from the TriNetX Global Collaborative Network spanning 2003–2025. Annual incidence rates were estimated for DMDD diagnosis, bipolar disorder diagnosis, antipsychotic prescribing, and mood stabilizer prescribing among patients aged 6–18 years. Segmented regression models were used to evaluate trends before and after the introduction of DMDD. Secondary analyses identified data-driven change points independent of the DSM-5 timeline. Following DMDD introduction, DMDD diagnoses increased steadily while bipolar disorder diagnoses declined. Antipsychotic and mood stabilizer prescribing did not show immediate changes and declined later in the study period. Data-driven analyses identified a change point in bipolar disorder diagnoses in 2009, several years before DMDD introduction, whereas prescribing change points occurred around 2021. Diagnostic and prescribing trends were therefore temporally dissociated. Changes in pediatric bipolar disorder diagnoses were not immediately associated with changes in psychotropic prescribing. The decline in bipolar diagnoses most likely reflects accumulating evidence against the validity of broad bipolar diagnoses in chronically irritable children, rather than a direct effect of DMDD's introduction. Changes in diagnostic labels do not automatically translate into changes in prescribing behaviors. Diagnostic trends should be interpreted with caution, particularly when the validity of the diagnostic categories themselves remains unclear."}