"Among the 2.6 million adults who had co‑occurring SMI [Serious Mental Illness] and an SUD [Substance Use Disorder] in the past year, 65.6 percent received either substance use treatment at a specialty facility or mental health care in the past year (Figure 31). Stated another way, about 1 in 3 adults with co‑occurring SMI and an SUD did not receive either type of care in the past year.

"Illicit drug use disorder is defined as meeting DSM-IV criteria for either dependence or abuse for one or more of the following illicit drugs: marijuana, cocaine, heroin, hallucinogens, inhalants, methamphetamine, or prescription psychotherapeutic drugs that were misused (i.e., pain relievers, tranquilizers, stimulants, and sedatives). There are seven possible dependence criteria for specific illicit drugs:

"Overall, lower levels of acquisitive offending and high-cost offending were recorded at follow-up. Among those who continued to offend, improvements in offending behaviour at follow-up, in terms of a decrease in its volume and/ or the costs associated with it, were observed. Crack users, injecting users, users with high SDS [Severity of Dependence Scores] scores, and those with previous treatment experience were more likely to offend than others at any point.

"In 2015, approximately 20.8 million people aged 12 or older had an SUD in the past year, including 15.7 million people who had an alcohol use disorder and 7.7 million people who had an illicit drug use disorder (Figure 27). An estimated 2.7 million people aged 12 or older had both an alcohol use disorder and an illicit drug use disorder in the past year (Figure 28). Thus, among people aged 12 or older in 2015 who had an SUD in the past year, nearly 3 out of 4 had an alcohol use disorder, and about 1 out of 3 had an illicit drug use disorder.

According to SAMHSA, "There was a net increase of 526 responding [substance abuse treatment] facilities between 2015 and 2016, to 14,399 facilities." (p. 11)

Federal spending on substance use disorder treatment and treatment research, as estimated by the Office of National Drug Control Policy (all figures final unless otherwise noted):

"NSDUH’s overall estimates of SUD include people who met the DSM-IV criteria for either dependence or abuse for alcohol or illicit drugs. In 2017, approximately 19.7 million people aged 12 or older had an SUD in the past year, including 14.5 million people who had an alcohol use disorder and 7.5 million people who had an illicit drug use disorder (Figure 39).

"NSDUH’s overall estimates of SUD [Substance Use Disorder] include people who met the DSM-IV criteria for either dependence or abuse for alcohol or illicit drugs. In 2018, approximately 20.3 million people aged 12 or older had an SUD in the past year, including 14.8 million who had an alcohol use disorder and 8.1 million who had an illicit drug use disorder (Figure 42). Among the 8.1 million people who had an illicit drug use disorder, the most common disorders were for marijuana (4.4 million) and misuse of prescription pain relievers (1.7 million).

"The percentage of recent drug users in State prison who reported participation in a variety of drug abuse programs rose from 34% in 1997 to 39% in 2004 (table 9). This increase was the result of the growing percentage of recent drug users who reported taking part in self-help groups, peer counseling and drug abuse education programs (up from 28% to 34%). Over the same period, the percentage of recent drug users taking part in drug treatment programs with a trained professional was almost unchanged (15% in 1997, 14% in 2004).

Cost Effectiveness of Substance Use Treatment

The RAND Corporation found that the additional spending needed to achieve a 1% reduction in the number of cocaine users varies according to the sort of program used, and that treatment is the most cost-effective:

Table comparing cost effectiveness of spending on treatment versus law enforcement for reducing substance use