Understanding Comorbid Axis I: Mental Disorders & Substance Use

Comorbid Axis I refers to the presence of two or more mental disorders in addition to a Substance Use Disorder. Substance Use Disorder is listed under Axis I, according to the Diagnostic and Statistical Manual of Mental Disorders (DSM).

In the DSM-IV, Axis I disorders included:

- Clinical disorders (e.g., mood, anxiety, eating, personality)

- Substance abuse

Axis II disorders were classified as "Personality disorders and mental retardation."

The distinction between Axis I and II was removed in the DSM-5. Current versions of the DSM use a single axis system to classify disorders.