Dual Diagnosis typically refers to an individual person with a mental disorder, co-occurring developmental disability and substance abuse disorder. People suffering from a mental health illness may turn to alcohol or alternative drugs to come out of that depression. The fields of mental health and drug use recovery have different cultures where integrated care can be challenging. One of the things that make dual diagnoses so difficult to treat is that it is hard to know where certain symptoms are coming from an integrated intervention the best treatment for dual diagnosis where a person receives care for both their diagnosed mental illness. The causes for dual diagnosis is difficult to approach as they can be caused in any way which affects their mental ability and it is difficult to identify as the studies apply differing criteria in defining developmental disabilities and their mental illness.