The most common diagnostic system for psychiatric disorders is the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), currently in its fifth edition. While the last DSM, DSM-IV, used multiaxial diagnosis, DSM-5 did away with this system.

What Are the Five Axes in a Multiaxial Diagnosis?

In the DSM-IV-TR system, an individual was diagnosed on five different domains, or "axes." In a single axis system like DSM-5 is, an individual is diagnosed in just one domain. For example, a clinical disorder, such as major depressive disorder, would be assigned. The multiaxial system was thought to give more detail.

Axis I: Clinical Disorders

Major psychiatric disorders were diagnosed on Axis I. When you think of psychiatric diagnosis, these are the kinds of disorders that probably come to mind. For example, major depressive disorder and post-traumatic stress disorder were diagnosed on Axis I. Learning disorder, such as reading or arithmetic disorders, and developmental disabilities, such as autistic disorder, were also diagnosed on Axis I.

Axis I tended to be reserved for major disorders that were thought to be somewhat episodic, meaning they typically have a clear onset and periods of remission or recovery.

This was not true of all Axis I disorders, however. Autistic disorders, for example, are not episodic.

Axis II: Personality Disorders or Mental Retardation

Axis II also included some conditions that we might consider psychiatric disorders, but these were thought to be longer-standing conditions that were typically present before age 18.

The personality disorders are longstanding, pervasive patterns of thinking and behavior that usually appear before the age of 18 but are typically diagnosed after 18, when the personality is considered more fully formed. These disorders are not thought of as episodic; they are considered stable and chronic.

Mental retardation (MR) is also a long-standing condition that must be present before the age of 18 and is stable over time. MR refers to significantly below-average intellectual functioning combined with deficits in adaptive behavior.

One rationale for the diagnosis of personality disorders and mental retardation on Axis II was that these are chronic conditions that should be separated from Axis I conditions in order to allow them to be highlighted since they convey important additional diagnostic information.

There was some controversy, however, about whether personality disorders are truly qualitatively different than Axis I clinical disorders, and whether they should remain on Axis II.

Axis III: Medical or Physical Conditions

Axis III was reserved for medical or physical conditions that may affect or be affected by mental health issues.

For example, if someone has cancer, and their illness and treatment are affecting their mental health, that would be important information to be conveyed in the diagnosis. So, the cancer diagnosis would be included on Axis III.

Alternatively, someone might have a medical condition that is impacted by their mental health. For example, someone with diabetes might not comply with their medical treatment regimen if they have a psychiatric disorder that causes impulsive or erratic behavior. Diagnosing the medical illness on Axis III was to help alert a clinician of a potential problem.

Axis IV: Contributing Environmental or Psychosocial Factors

Often, a psychiatric diagnosis happens in the context of major environmental or social stressors. For example, job loss, divorce, financial problems or homelessness may contribute to the development or maintenance of a mental health condition. A psychiatric disorder can also contribute to the development of these stressors. These important contextual factors were coded on Axis IV.

Axis V: Global Assessment of Functioning

The last axis, Axis V, was reserved for the global assessment of functioning (GAF). The GAF is a number between 0 and 100 which was meant to indicate your level of functioning, or your ability to engage in adaptive daily living.

Lower scores indicated lower functioning, with a score closer to zero indicating that a person was incapable of maintaining their own safety or basic hygiene or was an imminent threat to the safety or welfare of others. Scores near 100 indicated superior functioning.

Why Did the DSM-5 Do Away With Multiaxial Diagnosis?

The multiaxial system was intended to help bring clinical and research attention to the axis II diagnoses. The DSM-5 has combined the first three axes into one in order to eliminate what are now thought to be the artificial distinctions between diagnoses. It also hopes that this will help clinicians, researchers, and insurance companies streamline information.