Dual diagnosis refers to which of the following?

• A. Co-occurring mental health and substance use disorders.
• B. Substance use disorder with an unrelated physical illness.
• C. Two separate substance use disorders.
• D. A single mental health disorder.

Answer: (A)

Dual diagnosis means experiencing a mental health disorder at the same time as a substance use disorder. The two conditions occur together and influence one another, which is why treatment plans focus on addressing both conditions simultaneously rather than treating one in isolation. For example, someone might have major depression and also struggle with alcohol use, and the best care integrates strategies for both conditions to improve outcomes.

This is not about a substance use disorder occurring with an unrelated physical illness, not about having two distinct substance use disorders, and not about just a single mental health disorder.