Dual diagnosis treatment is used to treat individuals who are suffering from both a mental health issue, such as depression, anxiety or post traumatic stress disorder, in addition to a drug or alcohol addiction . Sometimes the psychological condition is pre-existing and is what drove them to abuse the substance. Other times, it’s the reverse, where the substance abuse led to the mental illness and emotional issues. Either way, dual diagnosis must be treated in a treatment center staffed by professionals who have the knowledge and training to provide specialized counseling.