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How Common Are Co-occurring Disorders?

Being diagnosed with a substance use disorder and a mental health disorder is often referred to as having a dual diagnosis. The disorders together are called dual disorders or co-occurring disorders. Co-occurring disorders are common among people seeking treatment in the mental health or addiction treatment settings.

Although people with this diagnosis may not have received treatment for both disorders, co-occurring disorders are, in fact, common. In a 1990 survey of over 20,000 U.S. adults, over half (53%) of those with a drug use disorder also had a co-occurring mental health disorder. A little over a third (37%) with an alcohol use disorder also had a psychiatric disorder (Regier et al. 1990). Among people with schizophrenia or bipolar disorder, the rates of co-occurring disorders appear to be even higher. About half of people with these diagnoses also have substance use disorders. According to the 2006 National Survey of Drug Use and Health, 5.6 million people in the United States have co-occurring substance use and mental health disorders.

Causes of co-occurring disorders

There appear to be genetic risk factors for substance use and certain mental health disorders, but genes alone cannot explain all cases of these disorders. Scientists cannot fully explain why some people develop mental health disorders and others do not. One theory that has received support is the stress-vulnerability model. This model holds that both stress and biological vulnerability work together to contribute to symptoms of mental illness.

Biological vulnerability refers to a tendency to develop a condition. People are born with or acquire this sensitivity very early in life. Vulnerability also refers to what a person has been exposed to early in life, such as exposure to a virus in the womb. Stress or environmental factors can trigger the onset of symptoms. "Stress" refers to the challenges faced in our lives. It is affected by our coping skills, social support, and involvement in meaningful activities.

People with a mental health disorder may be more biologically sensitive to the effects of substances. They may also use substances to cope with symptoms or facilitate social connections. In general, people who have a mental health disorder are at much greater risk of also having a substance use disorder.

It is not known why people become addicted to a certain substance and not another. Some research indicates that access and exposure to substances may be the most important reason. That is, the substances people have access to determine the type of substance use disorder they are likely to develop.

To find out more about co-occurring disorders, visit our page What Are Co-occurring Disorders?

Effective treatment

In traditional care, mental health disorders and addiction problems are often treated separately. We now know that co-occurring mental health and substance use disorders impact one another and must be treated together. For care to be effective, both disorders must be treated at the same time, in the same place, by the same treatment team. This is called integrated treatment.

Integrated treatment can stabilize the symptoms of co-occurring disorders and provide the foundation for lasting recovery from substance use and psychiatric disorders. A variety of treatment approaches are used in treating co-occurring disorders. These include treatment for substance use and mental health disorders, client education, shared decision making between client and caregivers, peer support, training in coping skills, and recovery support.

To learn more, visit Integrated Treatment Produces Best Outcomes

Screening Tools

Screening tools help clinicians begin their assessment of clients with an effective, protocol-driven method. We've collected some of the more commonly used public-domain screening tools.

An effective, integrated
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The Co-occurring Disorders Program is the first comprehensive treatment program for people with non-severe mental health disorders that co-occur with substance use disorders. Learn more

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