Disruptive mood dysregulation disorder (DMDD) is common among children presenting to mental health clinics. DMDD symptoms are often persistent, which can cause severe functional impairment and many adverse consequences if left untreated. However, there are few evidence‐based psychotherapeutic interventions for its treatment. Therefore, the present study aimed to investigate the effectiveness of cognitive‐behavioral therapy (CBT) for children with DMDD. Fifty‐three children with DMDD were randomized to the CBT group or wait‐list control group. Those in the intervention condition were asked to complete a 3‐month follow‐up assessment. Children, their parents, and teachers answered the questionnaires before and after treatment and a 3‐month follow‐up. The experimental group was treated with CBT (individual with the child) during 15 weekly sessions. ANCOVA analyses showed a significant difference between the two groups regarding irritability, overt aggressive behaviors, and internalizing and externalizing problems (as reported by children, parents, and teachers). Based on the comparison of means, children in the CBT group showed less aggressive behavior, anger outbursts, and irritability than children in the WLC group after treatment. Also, based on the within‐subjects differences, symptom improvements in the CBT group were largely maintained through the follow‐up period, without evidence that symptoms significantly worsened. Our findings showed that CBT can be a useful treatment for improving the symptoms of anger, aggression, and irritability in children with DMDD, and it can be considered a suitable approach to the treatment of DMDD.
