Dual diagnosis treatment addresses both substance use disorder and other mental health conditions at the same time. For many, mental health conditions are at the root of drug and alcohol use. These instances are called co-occurring disorders and dual diagnosis treatment treats both conditions at once. Understanding Dual Diagnosis Treatment Dual diagnosis treatment looks different for each client, and depends on what co-occurring conditions are at play. Mental health conditions that are treated include, but are not limited to: Anxiety Depression Bipolar Disorder Eating Disorders Attention