The treatment of co-occurring substance use and mental health disorders is a relatively new and increasingly successful strategy for care. However, the substance use and mental health treatment disciplines do not always speak a common language. Establishing a common language between the two fields is an important step toward improving care for people experiencing co-occurring disorders.

The treatment of co-occurring disorders is a relatively new field. However, the development of evidence-based practices for treating and caring for people with co-occurring substance-related and mental health disorders offers great promise.

The term co-occurring disorder (also known as “COD”) refers to co-occurring substance-related and mental health disorders. People with a COD have one or more substance-related disorder as well as one or more mental disorder.

Both the substance abuse and mental health fields have made considerable progress toward addressing the needs of people with COD. This is also true in homeless service settings. Twenty-six percent of all sheltered persons who are homeless have a severe mental illness and 37% of all sheltered adults who are homeless have chronic substance use issues. (1)

However, clinicians in homeless service settings are often trained in one discipline, like addictions counseling or behavioral health. Each discipline has its own language to describe common conditions experienced by people with co-occurring disorders. Developing a common language can help improve communication between the two fields. It is also critical to develop a consensus on how to provide care that addresses the needs of persons with co-occurring disorders.

Here are some common definitions related to substance use, as defined by SAMHSA’s Co-Occurring Center for Excellence (COCE):

• Substance abuse is defined as a pattern of substance use manifested by recurrent and significant negative consequences related to the repeated use of substances.
• Substance dependence refers to the cognitive, behavioral, and physiological symptoms indicating that a person continues to use the substance despite related consequences. These could include: increased tolerance for the drug, an obsession with obtaining the drug, or the persistence in using the drug in the face or serious consequences.
• Substance use disorders include intoxication or withdrawal, which can often present as mental disorders, such as delirium, dementia, amnesia, anxiety, or psychosis.

Mental disorders have their own terminology:

• Major relevant mental disorders for co-occurring disorders include schizophrenia and other psychotic disorders, mood disorders, anxiety disorders, and personality disorders.
• Serious mental illness is described as a condition of a person over 18 who currently or at any time over the past year have had a diagnosable mental, behavioral, or emotional disorder that limits major life activities.

Providers in homeless service settings know that not only clinicians serve and care for individuals with COD. Outreach workers, shelter intake staff, case managers, and other staff across settings interact with clients coping with COD. Gaining a simple understanding - and common language - for substance use and mental health disorders is the first step toward helping people to access the most appropriate care.

The second step is to begin to understand the distinction between a person with COD and a person who requires COD services.

At the individual level, COD exist when one disorder of each type can be established independent of the other, and are not simply symptoms resulting from one. However, many clients, though they do not fall under this definition, would benefit from COD services. To help providers plan programs to meet their needs, SAMHSA recommends a service definition of COD. A service definition reflects more meaningful descriptions for at-risk populations targeted for prevention and early detection.

A service definition of COD includes:

• Individuals who are diagnosed with one disorder, but have symptoms of the other, independent of the first.
• Individuals with one disorder, with signs of a co-occurring condition. Suicidal risk within the context of a substance use disorder is an example. Here, a mental health symptom is brought on by the substance use disorder.
• Individuals who are “post-diagnosis” in the sense that one or both of their substance-related or mental disorders have resolved for a substantial period of time.

In these cases, COD services may be appropriate, absent of an individual diagnosis. Any and every initiative within a program must clarify the definition of COD. For a system to be responsive to the range of needs of people with COD, a service definition is appropriate. At the program level, a narrower individual definition might help providers deliver directed care.

With any program, effectively caring for individuals with COD is a tall task. Providers must be able to identify clients who might be in need of services, and have the community resources to refer clients to proper agencies. Programs might also consider hiring providers from both the mental health and substance use fields.

A stronger understanding of the definitions of co-occurring disorders can help everyone improve care for people coping with COD. These definitions can help programs conduct integrated screenings to establish the need for an in-depth assessment for COD and identify those who would benefit from integrated care. A common language can also build bridges across different approaches to treatment and provide a starting point for dialogue between providers.

The information in this article is drawn from “Definitions and Terms Relating to Co-Occurring Disorders, Overview Paper 1,” published by SAMHSA’s Co-Occurring Center for Excellence (COCE). Visit the COCE website to learn more about co-occurring disorders.

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(1) These statistics refer to a given night in January, 2008. U.S. Department of Housing and Urban Development (HUD). (2009). The 2008 Annual Homeless Assessment Report to Congress. Washington, DC.