Treatment for Substance Use Disorder With Co-Occurring Mental Illness

Substance use disorder is a highly prevalent condition, leading to significant morbidity, mortality, and burden on the health care system. Substance use disorders are overrepresented among individuals with a mental illness. The term "dual diagnosis" was introduced by the World Health Organization in the mid-1990s and refers to the co-occurrence of a substance use disorder with mental illness-a more recently used term is "co-occurring disorders." In the past decade, substantial progress has been made toward expanding psychotherapeutic and pharmacotherapeutic treatments for treating co-occurring disorders. Yet management remains a challenge among clinicians and has been a source of confusion and considerable controversy. This review describes the epidemiology and treatment of co-occurring disorders, with a focus on major depressive disorder, anxiety disorders, and attention-deficit hyperactivity disorder. Substance use may make diagnosis of the underlying psychiatric condition difficult, and a period of abstinence may be necessary. Findings from efficacy studies of medications used to treat co-occurring disorders are reviewed, as are results of preliminary studies of newer treatments, such as topiramate, ketamine, noninvasive brain stimulation, and deep brain stimulation. Treatment recommendations that combine medications and psychosocial interventions are summarized.