In recent years, the field of clinical psychology has seen a growing movement toward the research and development of transdiagnostic treatments. Transdiagnostic approaches have the potential to address numerous issues related to the development and treatment of mental disorders. Among these are the high rates of comorbidity across disorders, the increasing need for efficient protocols, and the call for treatments that can be more easily disseminated. This chapter provides a review of the current transdiagnostic treatment approaches for the treatment of youth mental disorders. Three different types of transdiagnostic protocols are examined: mechanism-based protocols, common elements treatments, and general treatment models that originated from single-disorder approaches to have broader reach. A case study illuminates how a mechanism-based approach would inform case conceptualization for a client presenting with internalizing and externalizing symptoms and how a transdiagnostic framework translates into practice.
12.1 Relationship Between IQ and Internalizing and Externalizing Symptoms in Children With Autism Spectrum Disorder and Children With ADHD