Introduction to Classifying Mental Disorders

What you’ll learn to do: describe how mental disorders are identified and classified

A person sitting in front of a laptop screen that is displaying various words related to mental health such as grief, post-traumatic stress, and anxiety.

Why is it important to classify abnormal behavior? Classification is important because it allows scientists to identify and group patterns of abnormal behavior. For example, in the case of depression, researchers might be able to identify common factors that help explain the origins of depression. Classification systems used in abnormal psychology aim to ease understanding and communication between clinicians and researchers by standardizing the language used around disorders. These systems also allow for consistent and reliable research about the diagnosis, prognosis, and treatment of disorders. The most popular classification system in the United States is the DSM-5, but the ICD-11 is another popular system used internationally.[1]

Important decisions are made on the basis of classification, such as deciding on which therapy to choose or which drug to administer. Classification is not without its criticism, however. It has the potential to dehumanize by labeling, but it does allow clinicians to better predict behavior—schizophrenia, for example, follows a more or less predictable course.

This section reviews the classification and assessment of abnormal behavior, beginning with the DSM-5.

  1. Lempérière T. L'intérêt des classifications en psychiatrie [The importance of classifications in psychiatry]. Encephale. 1995 Dec;21 Spec No 5:3–7. French. PMID: 8582303.