The Substance Abuse and Mental Health Services Administration (SAMHSA) conducted a study examining behavioral health spending from 1986 to 2005.  The study found that U.S. behavioral health spending totaled $135 billion in 2005, accounting for 7.3 percent of the $1.85 trillion spent on health care.  In contrast, they study notes that behavioral health spending accounted for 9.3 percent of all health spending in 1986.  SAMHSA found that spending on substance abuse treatment represented 1.2 percent of all health care spending in 2005, down from 2.1 percent in 1986.  In addition, the spending on mental health treatment decreased as a proportion of total health spending, from 7.1 percent to 6.1 percent over the same period.  Finally, the study found that the proportion of mental health treatment funded by Medicaid grew from 17 percent in 1986 to 28 percent in 2005

From the study:

The SAMHSA Spending Estimates (SSE) initiative was created to provide policy makers with essential information on expenditures for mental health (MH) and substance abuse (SA) treatment services. To strengthen their ties to other all-health accounts, the SSE was designed to mirror the National Health Expenditure Accounts (NHEA) produced annually by the Centers for Medicare and Medicaid Services (CMS). Therefore, the SSE relies heavily upon the definitions and concepts used in the NHEA.

The estimates presented in this report are a baseline from which the impacts of the MHPAEA and the PPACA can be measured in the future. The six policy questions for which this report presents a 1986 through 2005 baseline are:

• How much was spent in the U.S. for mental health (MH) and substance abuse (SA) treatment?
• Who paid for MH and SA services and how much did they spend?
• How much was spent by provider type?
• How much was spent by type of setting on MH and SA services?
• How has spending changed over time?
• How did MHSA expenditures compare with those for all health care spending?

Full Study: National Expenditures for Mental Health Services & Substance Abuse Treatment, 1985-2005 (PDF | 1.13MB) 

Substance Abuse and Mental Health Services Administration. (2011). National expenditures for mental health services & substance abuse treatment, 1986- 2005.