How common are co-occurring substance use disorders and other mental illnesses?

Many people who have a substance use disorder also develop another mental illness, just as many people who are diagnosed with mental illness are often diagnosed with a substance use disorder. Studies show that about half of people who experience a mental illness will also experience a substance use disorder at some point in their lives and vice versa.1, 2  

1 Ross S, Peselow E. Co-occurring psychotic and addictive disorders: neurobiology and diagnosis. Clin Neuropharmacol. 2012;35(5):235-243. doi:10.1097/WNF.0b013e318261e193.

2 Kelly TM, Daley DC. Integrated Treatment of Substance Use and Psychiatric Disorders. Soc Work Public Health. 2013;28(0):388-406. doi:10.1080/19371918.2013.774673.