The most common diagnostic system for psychiatric disorders, outlined in the Diagnostic and Statistical Manual of Mental Disorders (currently in its fourth edition, text revision; DSM-IV-TR), uses multi-axial diagnosis.
What Is Multi-Axial Diagnosis?
In the DSM-IV-TR system, an individual is diagnosed on five different domains, or "axes." In a single axis system, an individual would be diagnosed in just one domain (for example, a clinical disorder, such as major depressive disorder, would be assigned).
This, however, conveys very limited information on what can be a very complex clinical picture. The multi-axial system in DSM-IV-TR was developed in part in order to capture more of the complexity surrounding psychiatric conditions. In the DSM-IV-TR, each axis can convey important information about both the symptoms experienced by the individual and the context surrounding those symptoms.
What Are the Five Axes in a Multi-Axial Diagnosis?
Axis I: Clinical Disorders
Major psychiatric disorders are diagnosed on Axis I. When you think of a "psychiatric diagnosis," these are the kinds of disorders that probably come to mind. For example, major depressive disorder and posttraumatic stress disorder are diagnosed on Axis I. Disorders of learning, such as reading or arithmetic disorders, and developmental disabilities, such as autistic disorder, are also diagnosed on Axis I.
Axis I tends to be reserved for major disorders that are thought to be somewhat episodic (i.e., they typically have a clear onset and periods of remission or recovery). But, this is not true of all Axis I disorders (e.g., autistic disorder is not an episodic condition).
Axis II: Personality Disorders or Mental Retardation
Axis II also includes some conditions that we might consider "psychiatric disorders," but these are thought to be longer-standing conditions that are 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 (although there is some recent research suggesting otherwise).
Mental retardation (or MR) is also a long-standing condition (it must be present before the age of 18) that 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 MR on Axis II is 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 is 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 is 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 might 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 (alternatively, a psychiatric disorder can contribute to the development of these stressors). These important contextual factors are coded on Axis IV.
Axis V: Global Assessment of Functioning
The last axis, Axis V, is reserved for the global assessment of functioning, or GAF. The GAF is a number between 0 and 100 which is meant to indicate level of functioning, or a person's ability to engage in adaptive daily living.
Lower scores indicate lower functioning, with a score of zero indicating that a person is incapable or maintaining their own safety or basic hygiene, or is an imminent threat to the safety or welfare of others. Scores near 100 indicate superior functioning.
American Psychiatric Association. Diagnostic and statistical manual of mental disorders, 4th ed, text revision. Washington, DC, Author, 2000.
Bernstein, DP, Iscan, C, Maser, J, Board of Directors, Association for Research in Personality Disorder, & Board of Directors, International Society for the Study of Personality Disorders. "Opinions of personality disorder experts regarding the DSM-IV Personality Disorders classification system." Journal of Personality Disorders, 21:536-551, 2007.