Co-occurring Disorders

Coordinating services for mental illness and substance abuse.

The Issue

Among people with mental illnesses, an estimated seven million have a co-occurring substance abuse disorder.1 The combination of substance abuse and mental illness (COD) affects people’s thoughts, perceptions, mood, behaviors, and relationships. Their distress is compounded by the highly stressful experiences of poverty and homelessness. Among people experiencing homelessness, about half of those with mental illness also have a co-occurring substance use problem.2

Individuals with COD tend to be more symptomatic, have multiple health and social problems, and require more costly care, including inpatient hospitalization. Services for mental health and substance use are often poorly integrated, creating difficulties for consumers seeking treatment. Only half of those with COD receive services in a professional substance use or mental health setting. Services more often occur in social service agencies, criminal justice systems, homeless service programs, or primary health care centers.

Shaping the Solution

Research and clinical care has resulted in proven approaches and interventions to stabilize and promote recovery for persons living with mental illness and substance use. The behavioral health workforce needs the knowledge and skills to:

  • Recognize COD symptoms
  • Conduct integrated screening and assessment
  • Develop integrated, client-centered, individualized treatment plans

Basic skills in outreach, case management, and motivational interventions should be considered fundamental, particularly for service providers working with people in non-traditional settings.


1Substance Abuse and Mental Health Services Administration. (2004). Results from the 2003 National Survey on Drug Use and Health: National Findings. DHHS Publication Number SMA 04-3964. Rockville, MD: SAMHSA.

2Caton, C.L., Dominguez, B., Schanzer, B., et al. (2005). Risk factors for long-term homelessness: findings from a longitudinal review of ?rst-time homeless single adults. American Journal of Public Health, 95(10):1753–1759. Kertesz S.G., Larson, M.J., Horton, N.J., et al. (2005). Homeless chronicity and health-related quality of life trajectories among adults with addictions. Medical Care, 43(6):574–585. Padgett, D.K., Gulcur, L., & Tsemberis, S. (2006). Housing First services for people who are homeless with co-occurring serious mental illness and substance abuse. Research on Social Work Practice, 16:74–83.

Email this page Bookmark and Share

COD services and systems should be:

  • Integrated
  • Coordinated
  • Flexible
  • Person-centered
  • Recovery-oriented
  • Trauma-informed
Co-occurring Disorders - Trauma - Issues
Co- Occurring Disorders, mental illness, substance abuse, issues
About half of people who are homeless and who have mental illness also have a substance use problem. The combination of substance use and mental illness affects people’s thoughts, perceptions, mood, behaviors, and relationships. Their distress is compounded by the highly stressful experience of homelessness.