What is the relationship between mental health disorders and addiction?

While not all individuals with addiction have mental health issues, nor do all persons with mental health issues have an addiction, there are high rates of correlation between these two disorders.  Up to 30 percent of patients suffer from both addiction and depression.  Anxiety and depression can lead a person to experiment and become addicted to drugs and alcohol in an effort to self medicate and unfortunately anxiety and depression are all too uncommon complications as an individual tries to heal from an addiction.