Concurrent Disorders

Concurrent disorders describes a condition in which a person has both a mental illness and a substance use problem. This term is a general one and refers to a wide range of mental illnesses and addictions. For example, someone with schizophrenia who abuses cannabis has a concurrent disorder, as does an individual who suffers from chronic depression and who is also an alcoholic. Treatment approaches for each case could be quite different.

Another term for concurrent disorder is comorbidity. In the United States, the terms dual diagnosis, dual disorder, or mentally ill chemical abuser are used to refer to concurrent disorder.¹ In Canada, dual diagnosis usually refers to someone with a mental disorder and a co-occurring developmental disability. (For more information, see Dual Diagnosis.)

It is challenging to determine conclusively how many people have a concurrent disorder because existing studies examine different populations and utilize differing screening tools. Further, people with concurrent disorders are frequently misidentified, as diagnosis can be more difficult because one disorder can mimic another. Relapse rates for substance use are higher for people with a concurrent mental disorder, as are the chances that symptoms of mental illness will return for those with a concurrent substance use problem. Depending on the setting, prevalence rates for concurrent disorders have been found to range from 20 to 80 percent.²

What is known conclusively, however, is that people with mental illness have much higher rates of addiction than people in the general population. Similarly, individuals with an addiction have much higher rates of mental illness than people in the general population. One large US study found that approximately a third of people with a mental or alcohol disorder had a concurrent disorder, and half of the people with drug problems had a mental disorder. A smaller study in Edmonton, Alberta had similar findings. In this study, almost a third of mentally ill individuals also had a substance use problem, almost a third of those with alcohol dependency also had a psychiatric diagnosis, and among illicit drug users, almost half had a mental illness.³

1. Centre for Addiction and Mental Health, "Answers to Common Questions on Concurrent Disorders," Journal of Addiction and Mental Health, September-October 1998, 16.
2. Centre for Addiction and Mental Health, "People with Concurrent Disorders," in Virtual Resource for the Addiction Treatment System, Section 3: Special Populations.
3. Centre for Addiction and Mental Health, "Answers to Common Questions on Concurrent Disorders," op. cit.

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Related Resources

Addiction Treatment Services

Drug and Alcohol Registry of Treatment

DART can provide you with information about drug and alcohol treatment services in Ontario. Search the online database or call the Drug and Alcohol Treatment Infoline at 1-800-565-8603 (toll-free, confidential, anonymous, open 24 hours).

Canadian Centre on Substance Abuse

The treatment services database contains approximately 1000 treatment programs across Canada. Each listing includes the addiction treated, the treatment setting, the target population, the language in which services are provided and a brief program description.

Information for Consumers and Families

Mental Health and Addiction 101: Concurrent Disorders

This free, online tutorial is intended for people who: work in non-clinical roles in the substance use and mental health fields, encounter people with substance use or mental health problems, in any work setting, or have friends or family with substance use or mental health problems. (Centre for Addiction and Mental Health)

Concurrent Substance Use and Mental Health Disorders: An Information Guide

This guide is for people with concurrent disorders and for their families. It is also for anyone who wants basic information about concurrent disorders, their treatment and their management. (Centre for Addiction and Mental Health, 2004)

A Family Guide to Concurrent Disorders (PDF)

Stresses the value of including families in the helping process and forms part of a larger effort to provide evidence-based services for families. Part of a three-phase study at CAMH comparing two interventions for families affected by concurrent disorders: an education and support group, and an educational manual and workbook. (Centre for Addiction and Mental Health, 2007)

Schizophrenia and Substance Use Website

Provides information for families, consumers and service providers, answering questions about concurrent disorders and providing resources and links directed at each audience. (Schizophrenia Society of Canada)

Professional Resources

Concurrent Disorders: Beyond the Label

An educational kit to promote awareness and understanding of the impact of stigma on people living with concurrent mental health and substance use problems. (Centre for Addiction and Mental Health, 2005)

Partnering with Families Affected by Concurrent Disorders: Facilitator's Guide

Tools and training for clinicians’ to provide education and support for family members of persons diagnosed with substance use and/or mental health problems. Part of a three-phase study at CAMH comparing two interventions for families affected by concurrent disorders: an education and support group, and an educational manual and workbook. (Centre for Addiction and Mental Health, 2007)

Policy and Research

Best Practices: Concurrent Mental Health and Substance Use Disorders (PDF)

Research information and recommendations for the screening, assessment, and treatment/support of this population. A resource for managers and staff of mental health, substance abuse, and integrated mental health/substance abuse services. (Health Canada, 2002)

Concurrent Disorders Policy Framework

This policy framework addresses the needs of people living with concurrent substance use and mental health issues, recognizing that as a population they and their families experience significant barriers in obtaining appropriate services, with poorer outcomes in comparison to those without concurrent disorders. (Concurrent Disorders Network of Ontario, 2005)

Concurrent Disorders Priority Knowledge Exchange Projects

Projects and activities under development in Ontario that will help to improve the ability of service providers in Ontario and the capacity of the Mental Health and Addiction systems to meet the needs of people affected by concurrent disorders, including family members. (Centre for Addiction and Mental Health)

The Co-Occurring Center for Excellence (COCE) (USA)

A resource for the field of co-occurring mental health and substance use disorders (known as concurrent disorders in Canada). Includes a catalogue of overview papers and a bibliographic database of research and resources in the field. (Substance Abuse & Mental Health Services Administration)

Increasing Linkages between Addiction and Mental Health Services in Ontario: Final Report of the Concurrent Disorders System Models Project (PDF)

Having two distinct systems for mental health and for addictions results in fragmentation. This report documents a community development process that was initiated to develop, implement and sustain a model of co-ordination among addiction and mental health services in two counties in Ontario. (Centre for Addiction and Mental Health, 2003)

National Program Inventory: Concurrent Mental Health and Substance Use Disorders

A national inventory of specialized concurrent disorders programs, with information from 37 agencies that provide services to individuals with concurrent disorders, including geographic area served, services provided, types of interventions, fee for service and inclusion/exclusion criteria. (Health Canada, 2001)

Dual Diagnosis Website (USA)

This American website features extensive online resources related to concurrent disorders for service providers, consumers, and family members.

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