Diagnostic and Statistical Manual of Mental Disorders

The Diagnostic and Statistical Manual of Mental Disorders (DSM) is a guide published by the American Psychiatric Association (APA) that provides a shared language and standardized criteria for classifying mental disorders. Its latest edition, the DSM-5-TR, came out in March 2022. While it is widely accepted internationally for diagnosing and treating mental disorders, it is often used alongside other classification systems. Other major psychiatric guides include the International Classification of Diseases (ICD), the Chinese Classification of Mental Disorders (CCMD), and the Psychodynamic Diagnostic Manual. Not all providers rely on the DSM-5, as the ICD’s mental disorder diagnoses are used globally, and research studies frequently measure changes in symptom scale scores rather than DSM-5 criteria to assess the real-world impact of treatments.

The manual is used by researchers, drug regulators, insurance companies, pharmaceutical firms, the legal system, and policymakers. Many mental health professionals use it to determine and communicate a patient’s diagnosis after an evaluation. In the United States, hospitals, clinics, and insurers often require a DSM diagnosis for all patients with mental disorders. Health-care researchers also use it to categorize patients for studies.

The DSM grew out of systems for collecting census data and psychiatric hospital statistics, as well as a United States Army manual. Since its first publication in 1952, revisions have gradually added more mental disorders and removed those no longer considered valid. Recent editions have been praised for grounding psychiatric diagnosis in empirical evidence, moving away from the theory-driven classification of earlier versions like DSM-III. However, they have also sparked controversy and criticism. Ongoing concerns include the reliability and validity of many diagnoses, arbitrary boundaries between mental illness and normal behavior, potential cultural bias, and the medicalization of everyday distress. The APA itself has noted that inter-rater reliability is low for several DSM-5 disorders, including major depressive disorder and generalized anxiety disorder.

**Distinction from ICD**

An alternative, widely used classification is the International Classification of Diseases (ICD), published by the World Health Organization (WHO). The ICD covers overall health as well as mental health—its chapter 6 specifically addresses mental, behavioral, and neurodevelopmental disorders. While the DSM is the most popular diagnostic system for mental disorders in the United States, the ICD is used more in Europe and other regions, giving it a much broader global reach. An international survey of psychiatrists in 66 countries found that the ICD-10 was used more often for clinical diagnosis, while the DSM-IV was more valued for research. This may be because the DSM emphasizes clear, operationalized criteria (e.g., requiring 5 out of 9 symptoms for at least 6 months for a diagnosis), whereas the ICD relies more on clinician judgment and qualitative descriptions of disorders. Since 1980, every code in the DSM has been an ICD-9 code, but DSM-5 includes both ICD-9 and ICD-10 codes. Although recent editions of the DSM and ICD have become more similar through collaborative agreements, each contains information the other lacks—for example, they list overlapping but different sets of recognized culture-bound syndromes. The ICD also focuses more on primary care and low- and middle-income countries, while the DSM targets secondary psychiatric care in high-income countries.

**Antecedents (1840–1949)**

**Census Office, AMA and ISI (1840–1911)**

The push to classify mental disorders in the United States began with the need for statistical data. The first official effort was the 1840 census, which used a single category: “idiocy/insanity.” Three years later, the American Statistical Association formally protested to the U.S. House of Representatives, calling the census’s nosology and statistics on insanity, blindness, deafness, and dumbness “the most glaring and remarkable errors,” noting that in many towns all African Americans were marked as insane, rendering the data essentially useless. The Association of Medical Superintendents of American Institutions for the Insane (the “Superintendents’ Association”) formed in 1844. In 1860, at an international statistical congress in London, Florence Nightingale proposed a plan that led to the first international model for systematic hospital data collection. In 1872, the American Medical Association (AMA) published its *Nomenclature of Diseases*, which included various “Disorders of the Intellect,” but it was short-lived. Edward Jarvis and later Francis Amasa Walker helped expand the census from two volumes in 1870 to twenty-five volumes in 1880. In 1888, the Census Office published Frederick H. Wines’ 582-page *Report on the Defective, Dependent, and Delinquent Classes of the Population*.