Among a nationally representative sample of U.S. adults with SUDs, 22% had been incarcerated before in their lifetime, which was twice the rate found in the total NESARC sample and is consistent with the vast literature documenting the strong links between SUDs, criminal justice involvement, and incarceration [1, 2]. This finding is unique in that it reports on the proportion with incarceration histories among the population of adults with SUDs as the denominator, as most past studies have reported on the proportion of SUDs among the population of adults with incarceration histories [8, 15]. The finding also brings up questions about differences between specific SUDs and use of SUD treatment among adults with incarceration histories in relation to those without such histories. As a result, we posed three additional research questions in this study and discuss our findings below.

One research question was: What proportion of adults with incarceration histories have used SUD treatment? We found that only a minority of adults with SUDs and incarceration histories have used SUD treatment. More specifically, 37% have used any alcohol use disorder treatment and 18% had used any drug use disorder treatment. Most commonly, the type of SUD treatment that was used for both alcohol and drug use problems was self-help groups like Alcoholics Anonymous or Narcotics Anonymous, although there were also relatively high proportions who used outpatient SUD treatment. A Cochrane Review of Twelve-Step programs like Alcoholics Anonymous concluded there was lack of experimental studies demonstrating the effectiveness of these programs [26], but a more recent systematic review found that there is substantial causal evidence of their effectiveness in reducing SUDs and SUD-related outcomes [27]. These self-help SUD treatment groups have become widespread and easily accessible [28]. Perhaps, the effectiveness of these programs may not be due to its specific structure, but because they are freely available, long-term, and easy accessible [29].

A second research question was: Among adults with SUDs, do those with incarceration histories use SUD treatment more than those without incarceration histories? Our findings showed that adults with SUDs and incarceration histories were more likely to use SUD treatment than those with no incarceration histories. Those with incarceration histories had 4.8 times the odds of using alcohol use disorder treatment and 4.7 times the odds of using drug use disorder treatment as compared to those without incarceration histories. Controlling for differences in background characteristics and SUDs, those with incarceration histories still had 3.1 times the odds of using alcohol use disorder treatment and 1.6 times the odds of using drug use disorder treatment. From our data we cannot determine whether the SUD treatment was evidence-based and whether it was accessed during the incarceration period or outside of that time. However, we can say that despite those with SUDs and incarceration histories being more likely to use SUD treatment, the utilization numbers among those with SUDs overall are low, regardless of incarceration history. Thus, the larger implication of our finding is that there continue to be barriers to care for SUD treatment among people with SUDs including those with incarceration histories. This is consistent with various other studies, such as a previous national study that found only one-third of those with SUDs and criminal justice involvement in the past year used SUD treatment in the past year [8]. Some studies have shown that mental health and SUD treatment along with social services can reduce recidivism among people who were formerly incarcerated [30, 31].

Our last research question was: What individual characteristics are associated with utilization of SUD treatment among adults with incarceration histories? Our regression analyses revealed no sociodemographic factors that were strongly associated with use of SUD treatment, but having an opioid disorder or stimulant use disorder was very strongly associated with use of SUD treatment. This was true both for adults with SUDs and incarceration histories as well as those with no incarceration histories and characteristics associated with SUD treatment utilization were largely similar between the two groups. Thus, it seems SUDs involving the “hard drugs” was more associated with SUD treatment than the more prevalent SUDs involving alcohol or cannabis. This finding is entirely consistent with a previous study that examined multiple international epidemiological surveys including the U.S. National Comorbidity Survey and found that cocaine and heroin use significantly predicted SUD treatment-seeking behaviors in the general population [32]. We agree with the study authors’ interpretation that this finding may be due to the possibility that opioids and stimulants are more likely than other substance to lead to impairments or symptoms that promote treatment seeking and often occurs later in the progression of drug use after other “gateway drugs” like alcohol and cannabis. This may also be important in the context of a recent study that found increased criminal justice involvement with increased opioid use [33]. Moreover, there is cause for concern that there is wide variability in quality, type, and intensity of treatment particularly for opioid use disorder. For example, one national study found that only 4.6% of justice-referred clients with opioid use disorder received agonist treatment compared to 40.9% of those referred from some other entity although agonist treatment can be highly effective for opioid use disorder [34]. This has spurred programs like the ones launched by the Rhode Island Department of Corrections [35] and by Rikers Island in New York City [36] to provide medication-assisted treatments for people with opioid use disorder in correctional facilities.

Together, the findings of this study highlight the need for public health interventions to address the high rates of SUDs among U.S. adults who have been involved in the criminal justice system. While we found higher utilization rates of SUD treatment among those with incarceration histories including those who have problems with opioids and stimulants, there is still much opportunity for increasing treatment utilization and ensuring use of evidenced-based practices. Importantly, a focus on prevention of SUDs would reduce the numbers who need SUD treatment and may possible curb criminal justice involvement [37, 38]. At the same time, the high incarceration rate among those with SUDs is not simply due to substance abuse, but a host of social determinants, such as unstable housing, poverty, and social networks; in fact, SUDs and criminal justice involvement share many of these same risk factors [39, 40]. Thus, comprehensive models of care that address these factors should be encouraged and evaluated for their effectiveness at population-based levels.

Our study had several limitations of note. First, this was a large-scale epidemiological examination of associations and lifetime incarceration and SUDs were assessed. The directionality of associations cannot be determined and it is likely many associations we found are bi-directional [41]. For example, we do now know whether the SUD treatment occurred before, during, and/or after incarceration. Second, the data were based on respondent self-report and reports about substance use and histories of incarceration may have been subject to various response biases. Third, the NESARC-III only sampled non-institutionalized adults so adults who are currently incarcerated or hospitalized were not included and so we may have missed an important segment of the population for our study. Fourth, we did not have detailed data on SUD treatment utilization so information about the intensity of SUD treatment services received and length of time were missing, which would be important for future study. These limitations notwithstanding, we believe the study provides important population data on SUDs and SUD treatment in the U.S. and our focus on adults with SUDs and incarceration histories highlights the need for more public health approaches to increase SUD treatment utilization in this population.