During training, mental health clinicians are taught the diagnostic criteria for the spectrum of psychiatric illness. James Morrison begins his book with the observation that few clinicians receive any formal education about the method for arriving at a diagnosis. His book, Differential Diagnosis Made Easier, presents a "roadmap for diagnosis" that leads the clinician through a disciplined process of considering a broad differential diagnosis and narrowing this differential to arrive at a working diagnosis.
In part I, The Basics of Diagnosis, the author describes his overall approach to diagnosis. He begins with a discussion of how to prioritize the various diagnoses that the clinician considers when first meeting a patient, proposing a "safety hierarchy" so that urgent causes—especially those due to substance use or medical illness—and readily treatable causes are considered first. Challenges in the diagnostic process, including thinking about atypical histories, distinguishing "normal" from pathologic degrees of symptoms, and capturing comorbidity, are addressed. Throughout this section, the author stresses the importance of maintaining a methodical approach to diagnosis.
Part II, The Building Blocks of Diagnosis, looks in-depth at several factors necessary to arrive at a sound diagnosis. This section highlights the importance of social and early life history, the intersection between physical and mental illness, and the impact of substance abuse. A brief chapter describes the essential contribution of the mental status exam and provides a basic overview of some of its components.
Part III, Applying the Diagnostic Techniques, provides an opportunity to practice the author's approach with a series of case histories. Readers are encouraged to independently apply the roadmap to the case material and then compare their analyses with the author's. This section is organized by diagnosis and includes cases illustrating mood disorders, anxiety, psychosis, cognitive disorders, substance use, and personality disorders. The author offers teaching points relevant to the case examples, such as tips for recognizing depression secondary to another condition and characteristics that might differentiate schizophrenia from other forms of psychosis.
Throughout the book, the author distills his advice into a list of diagnostic principles, detailed charts of differential diagnoses, medical illnesses that can cause psychiatric symptoms, and common psychiatric comorbidities, as well as a visual presentation of the roadmap to diagnosis. His case analyses serve to reinforce the roadmap method and provide examples in which this systematic approach allows the author to avoid missing an important diagnosis.
Morrison succeeds in creating a useful resource for clinicians to learn a systematic approach for arriving at diagnoses. This book is most likely to be appropriate for students and those in early postgraduate training, as well as more experienced clinicians endeavoring to teach this material. For these readers, it could also serve as a useful foundation for building a thoughtful approach to psychiatric diagnosis.
