Increases in treated cases drove 87% of spending growth; cost per case drove 13%
RESEARCH TRIANGLE PARK, N.C., March 19, 2026 /PRNewswire/ – A new study, led by researchers at the independent scientific research institute RTI International and the Bureau of Economic Analysis, found that national spending on treatment for mental health and substance use disorders (SUD) grew from $40.9 billion in 2000 to $139.6 billion in 2021, driven primarily by a substantial rise in the number of people receiving care. Increases in treated cases drove 87% of spending growth; cost per case drove 13%.
The study, published in Health Affairs, used data from the Bureau of Economic Analysis Health Care Satellite Account to examine more than two decades of treatment spending and its underlying drivers. Researchers determined that in 2021, 5.5 percent of total medical spending in the United States was for treating mental health or substance use disorders.
“Mental health and substance use disorders are major contributors to premature mortality in the United States, including deaths from suicide, drug overdoses, accidents and liver cirrhosis,” said lead author Tami Mark, Ph.D., a Distinguished Fellow at RTI.
“Understanding what the U.S. is spending on treating mental health and substance use disorders and what is driving spending growth is essential for policymakers and health systems working to improve access, quality and outcomes.”
Growth varied by condition. Treatment for mood disorders was the single largest category of mental health spending in both 2000 and 2021. Anxiety disorders and attention-deficit/hyperactivity disorder (ADHD) showed some of the fastest increases in real per capita spending. Substance use disorders had the greatest growth in the number of treated cases.
The study also notes that changes in diagnostic criteria, reductions in stigma, expanded insurance coverage and growth in the availability of medication-based and primary-care-delivered treatment may all have contributed to increased treatment use. The researchers underscore the need for stronger data systems to connect treatment with long-term outcomes, including recovery, improved functioning, quality of life and general well-being.
Learn more about RTI’s behavioral health research
Learn more about RTI’s substance use research
About RTI International
RTI International is an independent scientific research institute dedicated to improving the human condition. Our vision is to address the world’s most critical problems with technical and science-based solutions in pursuit of a better future. Clients rely on us to answer questions that demand an objective and multidisciplinary approach—one that integrates expertise across social, statistical, data, and laboratory sciences, engineering, and other technical disciplines to solve the world’s most challenging problems. For more information, visit www.rti.org.
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SOURCE RTI International
