RESEARCH WEEKLY: March Research Roundup 

By Kelli South

(March 31, 2021) Research Roundup is a monthly public service of the Office of Research and Public Affairs. Each edition describes a striking new data point about serious mental illness and summarizes recently published research reports or developments. This month’s Research Roundup is dedicated to selected data and research from our latest evidence brief on serious mental illness and co-occurring substance use disorders. 

DATAPOINT of the month 

One in four people with serious mental illness also have a substance use disorder 

At any given moment, an estimated one in four people with a serious mental illness also have a co-occurring substance use disorder. Co-occurring serious mental illness and substance use disorders are extremely common and make this population particularly vulnerable to negative consequences like more severe mental illness symptoms, increased risk of involvement with the criminal justice system and homelessness, and increased barriers to receiving adequate treatment for both of their illnesses. 

Substance Abuse and Mental Health Services Administration. (2019). National Survey on Drug Use and Health (Tables 8.12A and 8.4A).  

RESEARCH of the month 

Prevalence of co-occurring disorders in the United States is on the rise 

According to an analysis of prevalence rates of co-occurring disorders in the United States over time, there was a 73% increase in the prevalence of co-occurring disorders between 2009 and 2019, despite a total population increase of just 6% over the same period.  Unfortunately, there is a dearth of research regarding why co-occurring disorders are becoming more and more prevalent. This alarming increase is worth investigating and should be closely monitored in the future.   

Substance Abuse and Mental Health Services Administration. (2019). National Survey on Drug Use and Health (Table 8.11A).  

Hancq, E., South, K., & Vencel, M. (2021). Dual diagnosis: Serious mental illness and co-occurring substance use disorders. Treatment Advocacy Center

People with co-occurring disorders are more likely to be arrested for a crime 

A 2018 study published in the International Journal of Law and Psychiatry found that people with a co-occurring disorder are seven times more likely to be arrested for a crime compared to those with neither illness and 16 times more likely to be arrested for a violent crime. This study mirrors findings of many others, all of which point to the overrepresentation of people with dual diagnoses at every stage in the criminal justice system.  

Prince, J. D., & Wald, C. (2018). Risk of criminal justice system involvement among people with co-occurring severe mental illness and substance use disorder. International Journal of Law and Psychiatry, 58, 1–8. 
 
Few people with a dual diagnosis receive any concurrent treatment for both illnesses 

Our analysis of SAMHSA’s 2019 National Survey of Drug Use and Health data revealed that only 12.7% of people with a co-occurring disorder received any treatment for both their serious mental illness and substance use disorder in 2019. This figure includes people who received any amount of treatment and does not account for the quality or duration of said treatment. This is alarming because it means that even fewer than 12.7% of people likely received quality, continuous treatment for their co-occurring disorders. 

Substance Abuse and Mental Health Services Administration. (2019). National Survey on Drug Use and Health (Table 8.22B). 

Hancq, E., South, K., & Vencel, M. (2021). Dual diagnosis: Serious mental illness and co-occurring substance use disorders. Treatment Advocacy Center
Kelli South is the research associate at the Treatment Advocacy Center.

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Research Weekly is a summary published as a public service of the Treatment Advocacy Center and does not necessarily reflect the findings or positions of the organization or its staff. Full access to research summarized may require a fee or paid subscription to the publications.  

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