Dual diagnosis is the condition of suffering from a mental illness and a comorbid substance abuse problem. Dual Diagnosis treatment is a relatively new innovation in the field of addiction recovery. Until the 1990s, people who were experiencing symptoms of a mental health disorder — anxiety attacks , depressive episodes, delusional behavior or mood swings — were treated separately from those who sought help for drug or alcohol abuse.

When these conditions overlapped, clients were often denied treatment for a mental illness until they got clean and sober. Unfortunately, because substance abuse is often driven by an underlying psychiatric disorder, this meant that many people with a Dual Diagnosis of addiction and a mental disorder never got the help they needed.