Last week we shared some of the latest large government *study on mental illness and substance abuse. One set of findings shows a high correlation between mental illness and substance abuse — not really surprising to those of us who work in both fields.

Depression was one of the mental health issues the study targeted. Some of the findings: 35.7 percent of youths who had major depressive episodes in the past year (2009), used illicit drugs compared with 18 percent among youths who did not have MDE.

Also, youths who had past-year MDE were more likely to be heavy alcohol users-4.2 percent compared to 1.9 percent.

More and more, addiction professionals and agencies are addressing the fact that there is much overlap between mental illness and addiction.

For example, sometimes people with mental illness use drugs or alcohol to relieve symptoms, or “medicate” themselves, in treatment-enter parlance. Though there may be a temporary relief, drug and alcohol abuse generally exacerbates the symptoms of mental illness and can potentiate or depotenize any psychiatric meds being use and making the meds become ineffective or harmful.

Additionally, some mental illnesses, including some depressions, anxiety disorders, psychosis, and other problems can be directly caused by drug and alcohol abuse. Symptoms may lessen or end with the discontinuance of alcohol or drugs. But substance abuse can damage brain tissue-sometimes the damage is permanent.

Mental health and addiction professionals should be screening patients for both mental illness and addiction and if both are present, they should do detailed evaluation to determine what the origin of the addiction and the mental illness: Did mental illness trigger substance abuse? Did substance abuse cause a mental illness? This will have an impact on how treatment is carried out.

*2009 NSDUH (National Survey on Drug Use and Health) conducted by the national SAMHSA (Substance Abuse and Mental Health Services Administration).