Co-Occurring Disorders: Mental Illness and Substance Abuse

Introduction to Co-Occurring Disorders

The simultaneous presence of both mental illness and a substance use disorder in a single individual — known as co-occurring disorders (CODs) — has become the focus of significant attention among behavioral health researchers, clinicians, and policymakers. Emerging evidence highlights the serious and challenging nature of these disorders. Within the population of individuals with serious mental illness, for example, substance use has been shown to adversely affect the course and outcome of mental health treatment ("Co-occurring disorders," n.d.).

The federal Substance Abuse and Mental Health Services Administration (SAMHSA) has estimated that 7.2 million Americans between the ages of 18 and 54 have CODs. Persons at risk for developing a COD include individuals with a serious and debilitating mental illness and those with a history of abusing alcohol and/or other drugs ("Co-occurring disorders," n.d.).

Dual diagnosis can be difficult to identify because the symptoms of one disorder often mimic the symptoms of the other. Many symptoms of drug abuse — such as extreme anxiety, depression, paranoia, delusions, and hallucinations — are similar to symptoms of mental illness. The impact these symptoms have on a person's life, causing severe decline in self-care and functioning, can also be a symptom of a psychiatric problem (Cutter, Elam, Jaffe, & Segal, 2008).

The families of people afflicted with a mental illness, and the professionals who treat these cases, can easily underestimate the severity of the person's problem with drugs or alcohol for several reasons: drug abusers can use substances covertly without their families knowing; the behavioral signs of drug use resemble the signs of mental illness and may be difficult to separate; and it takes time to unravel the interacting effects of substance abuse and mental illness (Cutter et al., 2008).

There are eleven categories of substance use disorders — including disorders related to alcohol, cannabis, cocaine, opioids, and nicotine — which are separated by criteria into abuse and dependence. The term "substance abuse" has come to be used informally to refer to both abuse and dependence. By and large, the terms "substance dependence" and "addiction" have come to mean the same thing, though debate exists about their interchangeable use. The system of care for substance-related disorders is usually referred to as the substance abuse treatment system ("Center for substance abuse treatment," 2007).

Normal, and even exaggerated, responses to stressful experiences should not be confused with a diagnosable mental disorder. Only when intense emotions, thoughts, and/or behaviors occur over extended periods of time and result in impaired functioning are they considered mental disorders ("Center for substance abuse treatment," 2007). Mental disorders are characterized by the nature and severity of symptoms, the duration of symptoms, and the extent to which symptoms interfere with one's ability to carry out daily routines, succeed at work or school, and form and maintain meaningful interpersonal relationships ("Center for substance abuse treatment," 2007).

The major categories of mental disorders relevant to COD include: schizophrenia and other psychotic disorders; mood disorders; anxiety disorders; somatoform disorders; factitious disorders; dissociative disorders; sexual and gender identity disorders; eating disorders; sleep disorders; impulse-control disorders; adjustment disorders; personality disorders; and disorders usually first diagnosed in infancy, childhood, or adolescence (APA, 2000).

Prevalence and Common Mental Disorders

The prevalence of co-occurring disorders is substantial. Research indicates that 37% of alcohol abusers and 53% of drug abusers have at least one mental illness. Of all people diagnosed with a mental illness, 29% abuse either alcohol or drugs. Approximately 50% of people with mental disorders are affected by substance abuse.

Research conducted by numerous government organizations and universities supports these figures. The National Co-morbidity Study, for instance, found that approximately half of the individuals surveyed who met criteria for a substance use disorder also met criteria for one or more lifetime mental disorders. The reverse was equally true: individuals who met criteria for a mental illness also met criteria for a substance use disorder at some point in their lives ("Co-occurring disorder," 2008).

Substance abuse disorders can occur alongside any mental illness; however, they are more likely to occur with severe mental illnesses such as bipolar disorder or schizophrenia. Other mental health conditions commonly co-occurring with substance abuse include antisocial personality disorder, manic episodes, panic disorder, obsessive-compulsive disorder, and phobias. In one study, 47% of people with schizophrenia also had a substance abuse disorder, and 61% of individuals with bipolar disorder had a substance abuse disorder. These individuals are four and five times as likely, respectively, to have a co-occurring disorder compared to the general population ("Co-occurring disorder," 2008).

Treatment Approaches for Co-Occurring Disorders

Perhaps one of the most effective forms of treatment for co-occurring disorders is integrated treatment. As the name implies, the patient receives treatment for both mental illness and substance abuse from the same clinician or from a coordinated team of clinicians. The team works together to ensure that different interventions are brought into alignment. In this way, the client perceives no division between mental health and substance abuse treatment, eliminating the confusion that can arise when obtaining care from two separate centers.

The strength of integrated treatment lies in individualized programming. Each client has a specific treatment plan tailored to his or her needs, allowing the individual to move at his or her own pace. This approach is intended to result in more effective treatment and, ultimately, long-lasting recovery ("Co-occurring disorder," 2008). It should be noted, however, that some dissenting opinion exists regarding whether integrated treatment is the most effective approach for two such distinct health problems.

Individuals with co-occurring disorders can recover. Because treatment for COD is two-fold, those involved must understand that dual diagnosis programs require time. Recovery should be regarded as a long-term goal — one that is attainable with proper and effective treatment. Perhaps the most difficult challenge associated with COD is simply identifying that both conditions exist ("Co-occurring disorder," 2008).

The Four-Quadrant Classification Model

The term co-occurring disorders (COD) refers to co-occurring substance-related and mental disorders. Clients said to have COD present with one or more substance-related disorders as well as one or more mental disorders. Importantly, the definition of a person with COD at the individual level must be distinguished from a service definition. At the individual level, COD exist "when at least one disorder of each type can be established independent of the other and is not simply a cluster of symptoms resulting from [a single] disorder" ("Center for substance abuse treatment," 2007).

A useful conceptual framework classifies clients into four quadrants of care based on relative symptom severity rather than diagnosis:

Quadrant I: Low addiction / Low mental illness
Quadrant II: Low addiction / High mental illness
Quadrant III: High addiction / Low mental illness
Quadrant IV: High addiction / High mental illness

This model provides a framework for understanding the range of co-occurring conditions and the level of coordination that service systems need in order to address them. For example, someone with acute mental illness symptoms and a substance use disorder may be assigned to Quadrant IV for a brief period, then move to a less severe quadrant as treatment progresses. Although the four-quadrant model has not yet been formally validated, SAMHSA's Co-Occurring Center for Excellence (COCE) uses it to guide discussion and further conceptual development ("Center for substance abuse treatment," 2007).

The four-quadrant model also provides a structure for moving beyond minimal coordination to fostering consultation, collaboration, and integration among systems and providers, in order to deliver appropriate care to every client with COD. Coordination, consultation, collaboration, and integration are not discrete points but reside on a continuum. It is important to note that these terms refer to organizational and provider behavior, not to service system structure or the physical location where services are provided ("Center for substance abuse treatment," 2007).