The Course and Treatment of Substance

Use Disorder in Persons With Severe Mental Illness Kim T. Mueser, Robert E. Drake, and Keith M. Miles There is now a widespread acceptance that persons with severe mental illness are at increased risk to develop substance use disorders (alcohol and drug abuse/dependence). Reviews of the prevalence of substance use disorders in clients with schizophrenia (Mueser et al. 1990), bipolar disorder (Goodwin and Jamison 1990), and the young, chronically mentally ill (Safer 1987) indicate a wide range of prevalence estimates, from as low as 10 percent to over 65 percent. Variability in prevalence rates can be attributed to differences across studies in factors such as the setting in which clients are sampled (e.g., community mental health center, acute inpatient, chronic inpatient), methods for assessing psychiatric and substance use disorders (e.g., structured clinical interview, chart review), and the demographic mix of the study sample (e.g., proportion of males) (Galanter et al. 1988; Mueser et al. 1995). Despite the variability in prevalence estimates, strong evidence indicates that the rate of comorbid substance use disorders in people with severe mental disorders is substantially greater than in the general population. The most compelling evidence supporting this is provided by the Epidemiological Catchment Area (ECA) study (Regier et al. 1990), which assessed psychiatric and substance use disorders in over 20,000 persons living in the community and in various institutional settings. The results of this study indicated that persons with a psychiatric disorder were at increased risk for developing a substance use disorder over their lifetime. Of particular importance, people with severe mental illness were especially vulnerable to substance use disorders. For example, those with schizophrenia were more than four times more likely to have had a substance use disorder during their lifetime than persons in the general population, and those with bipolar disorder were more than five times as likely to have such a diagnosis. The high rate of substance use disorders among persons with severe mental illness has important clinical implications, because their substance abuse is associated with an array of negative outcomes. Common negative consequences include increased vulnerability to

relapses and rehospitalizations, greater depression and suicidality, violence, housing instability and homelessness, noncompliance with medications and other treatments, increased vulnerability to human immunodeficiency virus (HIV) infection, increased family burden, and higher service utilization and costs (Bartels et al. 1993; Clark 1994; Bartels et al. 1992; Cournos et al. 1991; Drake et al. 1989; Yesavage and Zarcone 1983). However, evidence also suggests that as dual-diagnosis clients attain stable remission, their vulnerability to these negative outcomes lessens (Bartels et al. 1993; Zisook et al. 1992). Thus, interventions that are successful at reducing substance abuse in clients with severe psychiatric disorders may also confer positive benefits in such areas as symptomatology, community functioning, service utilization, and costs of treatment. In this chapter the authors begin with a discussion of issues in the assessment of substance use disorders in persons with severe psychiatric disorders. Following this, an overview provides a natural history of substance use disorders in both the general population and among the chronically mentally ill. Next, the failure of the parallel treatment system for dually diagnosed clients is briefly reviewed, followed by a description of more recently developed integrated substance abuse and mental health methods. Preliminary data are then presented from a 3-year study by the New Hampshire-Dartmouth Psychiatric Research Center of integrated treatment for dual-diagnosis clients. The implications of research on integrated treatment approaches for policy decisions are discussed in a concluding section, as are future directions for research in this area.