ICD and DSM: Similarities and Differences Between the Two Manuals

There are two major systems of diagnosing psychological illness. These are the DSM and the ICD. Although the DSM is used by most psychology students and professionals is it the best option? What are the differences between the two? Are the two methods lacking in anything? In this article, we find the answers.
ICD and DSM: Similarities and Differences Between the Two Manuals

Last update: 17 January, 2022

There are two major diagnostical manuals of clinical psychology and psychiatry that list investigated disorders. These are the DSM and the ICD. It’s interesting to study the similarities and differences between the two manuals in order to choose which one is best to work with.

Both are extremely comprehensive classifications. They cover all areas of mental health. For example, neurodevelopmental and dissociative disorders, somatic symptom disorders, sexual dysfunctions, paraphilic disorders, and personality disorders.

Psychology is built on a classification system of disorders. This means that, from a series of psychopathological traits or symptoms, specific disorders or conditions are constructed that define cognitive economics.

For example, when a professional psychologist diagnoses depression, the definition in these two manuals reports a series of symptoms that the patient exhibits, or is likely to exhibit. In this particular condition, the definition includes feelings of apathy, crying, and suicidal thoughts.

However, within the disorders themselves, there are subcategories. For this reason, it’s necessary to define both common and differential elements between the different disorders and other diagnostic categories.

The DSM (Diagnostic and Statistical Manual of Mental Disorders) and the ICD (International Classification of Diseases) both use classification systems with diagnostic labels. However, the ICD is much older while the DSM has gained great importance in the field of mental health thanks to its updates.

An image of a psychologist and patient.

Brief history of the ICD and the DSM

Classification systems were born in the late 19th century with the father of diagnostic classification, Emil Kraepelin. He claimed:

“As we do not know the causes of mental disorders and any explanatory theory that we give is very weak; the best we can do to classify people is to use the observable symptoms and signs, the clinical manifestations, and for the system to account for the time trajectory ”.

The first DSM, (it’s currently in its fifth update, the DSM-5) was published as an adaptation of the ICD-6. The first two editions of the DSM were manuals quite similar to the ICD. However, from the third edition onward, the DSM followed its own system.

The DSM classifies disorders based on consensus. In other words, groups of experts undertake different diagnostic categories and these are the definitions used to make a diagnosis.

Therefore, it contains elements of arbitrariness and high subjectivity. However, in the case of the ICD, the disorders are established by the World Health Organization (WHO) and its member states.

After being improved, the ICD-11 perfectly addressed the gaps of the ICD-10. Indeed, it incorporates medical updates, discoveries, and certain changes in thinking. There are also specific updates related to enhanced coding structure, international usage, digital readiness, and user-friendliness.

Similarities Between the DSM and the ICD

Before talking about the differences between the DSM and the ICD, we need to discuss their similarities. Indeed, there are many. For instance, both manuals are classification systems for mental disorders based on the symptoms observed that covary with each other. Furthermore, both are systems that are widely established and used internationally for the diagnosis of mental disorders in adulthood and also in childhood and adolescence.

On the other hand, both are multiaxial systems. In other words, they’re organized considering various axes. These are aspects of clinical reality. However, in the DSM-5, these were eliminated. In turn, both classifications are intended to give or establish diagnostic criteria to increase the reliability of clinical judgments.

Other common characteristics are:

  • Deletion of the term mental illness. They use the word disorder instead.
  • Ateoricism. Diagnoses are based on descriptions of symptoms and not psychological theories.
  • Clinical significance. It isn’t sufficient for a series of symptoms to be met in order to grant a diagnosis. In fact, the symptoms must be further assessed to ascertain that they cause clinically significant discomfort or deterioration.
  • Polyethics. Not all specified symptoms of a disorder are necessary in order to make a diagnosis.

Differences between the DSM and the ICD

The DSM is a manual written by the APA (American Psychology Association). Hence, it originated in the United States. In fact, the DSM-5, and all its previous editions represent the de facto standard. In other words, it’s a manual that hasn’t been okayed or legitimized by any standardization body. Nevertheless, many people accept it as legitimate.

This can be explained by the true revolution that the DSM-III brought about with its system based on descriptions of symptoms and specific criteria. The ICD took longer to adopt this conceptual change, but they did eventually, and on an international basis. In the DSM, unlike the ICD, participation is purely American.

On the other hand, the ICD is a manual approved and written by the WHO. It’s based on the European diagnostic classification systems. Furthermore, the ICD-11 included in its team professionals from many geographical areas with different languages and economies. Therefore, it’s a completely cross-cultural tool.

Variations in diagnoses

The most interesting differences between the DSM and the ICD diagnoses are undoubtedly those that involve the diagnostic criteria of each disorder. Strangely, these two important manuals in the area of psychiatry and psychology don’t coincide when it comes to diagnosing certain disorders.

One example concerns the differences in the diagnosis of autism spectrum disorders. For example, the ICD-11 specifies and analyzes the absence of functional language in this condition. However, the DSM-5 merely invites the reader to consider it as a possibility.

Another example is the classification of social communication disorder. The ICD-11 included this condition in the language development disorders section. However, the DSM-5  classifies it within the communication disorders section.

These differences in diagnoses are not the result of competition between the two manuals or the different opinions of various experts. In fact, both publications face the problem of low existing reliability, hence low diagnostic validity. This makes an honest and complete classification extremely complicated.

Poor reliability of some categories

The reliability of the categories in both manuals can be questioned. For example, in generalized anxiety disorder, there’s a reliability of 0.2. However, in the case of post-traumatic stress, the reliability is 0.67. As more disorders are added, the reliability decreases. In fact, the more categories there are, the more difficult it is for the judges to agree. That’s because there’s more probability of error.

Along the same lines, in both manuals, there’s excessive comorbidity between disorders. In fact, about 60 percent of people who receive a diagnosis, receive two more. This means that there may be a person diagnosed with secondary major depression, panic attacks, generalized anxiety, and emotional dependence.

In fact, the comorbidity of diagnoses is extremely high. This may be because the classifications aren’t effective and there are too many shared symptoms. In effect, the boundaries of the disorders become unclear.

Which one should we use?

Both qualifying systems are extremely similar. If you’re a professional in psychology or psychiatry and are wondering which diagnostic system to choose, Geoffrey M. Reed, a professional who participated in the development of the ICD-11, has something to add. Reed argues that the DSM-5, being of American origin, didn’t want any international participation in its elaboration.

In contrast, WHO Member States ensured that the ICD-11 reflected cultural and linguistic particularities in its classification system. Reed said:

“The nature and values of health systems in Europe are very different from those in the United States, and it is not clear that a product based on North American concepts is the most appropriate. For this reason, the WHO is immersed in a global and multidisciplinary process for the development of the next ICD ”.

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  • Gutiérrez, M., Peña, L., Santiuste de Pablos, M. et alt. Comparación de los sistemas de clasificación de los trastornos mentales: CIE-1O y DSM-IV. Revisión.
  • Reed, G., Anaya, C. y Evans, S. (2012). ¿Qué es la CIE y por qué es importante en la psicología? International Journal of Clinical and Health Psychology, 12(3), 461-473.