Dual diagnosis, also referred to as co-occurring disorder, is when someone experiences a mental illness (bipolar, anxiety, depression, PTSD, etc.) and a substance abuse problem simultaneously. Either substance abuse or mental illness can develop first. Someone with a mental health condition may turn to drugs and alcohol to self-medicate and try to alleviate their mental health symptoms, making the condition even worse. Substance abuse can also lead to mental health problems because of the effects drugs have on a person’s moods, thoughts, brain chemistry and behavior. People with co-occurring disorders need a specialized form of treatment, referred to as integrated services or dual diagnosis treatment.