Given that children and adolescents can never be thought of simply as “little adults” but rather as patients with their own unique developmental, psychological, and biological characteristics, it is crucial that clinicians recognize how psychopathology presents differently in this population. Key differences between children, adolescents, and adults regarding epidemiology, diagnostic criteria, and treatment are described below for mood disorders, anxiety disorders, trauma and stressor-related disorders, and psychotic symptoms.

The first edition of Introduction to Psychiatry is a textbook designed to reach medical students, house staff, primary care clinicians, and early-career mental health practitioners. It is the editors’ hope that this text will enable its readers to understand the neuroscientific basis of psychiatry, best practices in the psychiatric assessment and treatment of the patient, the current understanding of core psychiatric diagnoses, and the important underlying issues of population health, public policy, and workforce recruitment and training that must be tackled to bring these advances to all.

Why create a textbook of psychiatry specifically for clinicians not trained for the mental health field? To answer this question, one must understand the troubling challenges facing the mental health workforce, the changing face of mental health care delivery, the enormous comorbidity between psychiatric illnesses and other health conditions, and the impact on non-psychiatric medical illnesses when a comorbid psychiatric disorder is present.