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Diagnostic Categories in DSM and ICD

Mental health professionals need a way of communicating about the disorders they treat. If a patient is referred from one doctor to another, there must be some common language to communicate about the nature of the disorder.

Terminology is provided in the U.S. by a guidebook called a Diagnostic and Statistical Manual. The version called DSM-5 was issued in 2013. It modified the previously existing DSM, changing the way of specifying disorders, adding some categories, merging some, and deleting others.

Over the years, every new version of the DSM has included such alterations, and they are always controversial. However, the document must evolve to reflect accumulating knowledge. With version 5, the DSM digital edition is officially a "living" document, meaning that it can be updated at any time, and the current online version is regarded as current.

What is DSM-5 and how is it used?

DSM-5 is published by the American Psychiatric Association. Psychologists know the American Psychiatric Association as "the other APA" because, for psychologists, APA usually refers to the American Psychological Association).

A function similar to the DSM is provided internationally by the ICD (International Classification of Diseases). While the DSM provides guidelines for treatment, the ICD system is just for coding disorders for reporting to insurance companies and recording incidents on medical records.

Therefore, the DSM is more like a textbook for clinicians, while the ICD codes are like a reference manual. The American Psychological Association summarizes the differences between the ICD and the DSM as follows ("ICD vs. DSM", 2009):

If that comparison sounds rather negative about the DSM, it is. The American Psychological Association is a competitor to the American Psychia­tric Association in the United States. Both are national organizations but they serve different professions and are frequently confused by non-experts.

With time, DSM and ICD categories increasingly overlap. American physicians have been required to use ICD classifications since 1979, and ICD codes are provided with every DSM category.

Research on harmful psychological dysfunctions is increasingly inter­national, like research in all areas of psychology. Either the DSM or ICD system can be used to classify disor­ders, and if there is disagreement between them, classification issues can be discussed in a research report.

Results of research feed back into revisions of both the DSM and ICD. For example, in DSM-5, many changes showed distinctions previously not emphasized.

Categories were merged if there was diagnostic confusion between them. That was the case for classic cate­gories of schizophrenia (paranoid, disorganized, catatonic, undifferen­tiated, and residual).

The committee updating the DSM decided these schizophrenia subtypes were not stable diagnostic categories. Now there is one category for schizo­phrenia, and symptoms like catatonia, if present, are noted separately.

DSM-5 provides an exhaustive classi­fication system for mental disorders, and so does ICD-11. In other words, nothing is left out.

If a person does not fit any diagnostic category, the special category NEC (Not Elsewhere Classified) is used in DSM and ICD. If those categories are used, a physician must spell out the reasons why a person does not fit other categories. Therefore, every patient can receive a diagnostic category, even if the category is "no other category."

What does it mean to be an "exhaustive" listing of mental disorders?

The American Psychiatric Association cautions that the diagnostic labels themselves are a "convenient shorthand." For a more complete description of an individual case, clinicians do assess­ments that include a personal history.

A DSM or ICD classification is only one part of a complex process of getting to know a client. The categorization can be changed later if appropriate.

DSM-5 identifies about 160 disorders and over 300 diagnostic categories. In the remainder of the chapter we will focus on major types of disorders recognized in both DSM and ICD.


ICD vs. DSM (2009, October). Monitor on Psychology, 40, p.63. Retrieved from:

Write to Dr. Dewey at

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