Among consumers in substance abuse treatment and mental health settings, and among members of the general population who need treatment and support but who have yet to seek help, the prevalence of co-occurring mental health and substance use disorders problems is very high. Despite the high prevalence, there is a reported lack of knowledge and training as to how best to identify and address needs.
Much of the literature on rates of comorbidity in the general population has been contributed by studies conducted in the United States. The report from the well-known Epidemiology Catchment Area (ECA) study75 is frequently cited as one of the first demonstrations of the high rates of co-morbidity in the general population. They found that the prevalence of substance use disorders among people with a concurrent mental disorder was 29% compared to 16% in the general population. A more recent report by Kessler et al.76 using data from the 1990-1992 National Comorbidity Study, found a total of 28.8% of the general population aged 15-54 had a concurrent (i.e., in the last year) alcohol and/or drug and mental disorder diagnosis. For those people with any current substance use disorder 42.7% showed a concurrent mental health problem; while 14.7% of those presenting with a psychiatric disorder showed a concurrent substance use disorder. This pattern of increased probability of mental health problems among people with substance use disorders, and vise versa, is mirrored in studies emanating from many developed countries.77-79
In Canada, and using methods and definitions which paralleled the U.S. National Comorbidity Study but with an age range that was 10-years wider (15-64), 18.6% of respondents from the 1990 Ontario Mental Health Supplement presented with one or more current alcohol, drug or mental health problems.80 A more recent report on co-morbidity of alcohol use and mental health disorders in the Ontario sample81 found that 55% of those with a lifetime alcohol diagnosis also qualified for a lifetime mental health diagnosis.
Epidemiological surveys suggest that while only a minority of individuals with alcohol or other substance abuse problems in the community enter treatment,82 the most severe cases with multiple concurrent mental disorders are the most likely to be treated.78,83,84 Kessler et al.76 have also shown that those in the general population with concurrent disorders present the highest probability of seeking treatment. This is corroborated by data from the 1992 National Longitudinal Alcohol Epidemiologic Survey which showed that respondents with past-year alcohol use disorders were twice as likely to seek help for their alcohol problems if they had a concurrent drug use disorder or major depression; and they were five times more likely to seek help when both these concurrent conditions were present.85 An unpublished secondary analysis of the Quebec Health Survey of 1987 provided data consistent with these findings in the U.S.86 Such findings are congruent with the recognition that those who seek help are the most severe cases in the general population.83
Clients of substance abuse treatment services who are diagnosed with a psychiatric disorder also use more health services generally,87 and are more often readmitted to treatment.88,89 The frequent use of expensive hospital and emergency services, and the persistence of both mental health and substance use disorders over time, contributes significantly to the extremely high economic cost associated with treatment and ongoing support for these individuals.90,91
Several studies have assessed the prevalence of concurrent substance use and mental health disorders among those people seeking help from either mental health or substance abuse treatment settings. Recent summaries of this literature,40,66 clearly show that the rates of alcohol and other drug problems are consistently higher among people seeking help from mental health services than the general population. Compared to the general population, the lifetime risk for developing alcohol dependence is 21 times more likely among individuals with an antisocial personality; six times more likely among those suffering from mania; four times more likely in people with schizophrenia; and twice the risk among those suffering from panic disorder, obsessive-compulsive disorder, dysthymia, major depression or somatization disorder.92 Weisner and Schmidt93 found that 38% of clients of mental health services in a California county reported one or more alcohol dependence symptoms in the previous year, compared to 27% in the general adult population and 65% in the criminal justice system. In the same study, 21% of mental health clients reported the use of three or more types of illicit drugs compared to 1% in the general population, and 12% of people arrested for a criminal offence.
Similarly, clients in substance abuse treatment have higher rates of mental health problems than are found in the community at large. Since those who suffer from concurrent disorders have a higher probability of seeking treatment than their counterparts in the general population,76 the vast majority of individuals admitted to treatment exhibit one or more clinical symptom.94-96 Studies have reported that close to 77% of those treated for alcohol-related disorders have experienced at least one other psychiatric disorder during their lifetime.97 Most clients suffer from at least one disorder of mood or anxiety;95,98-100 and the rates for personality disorder range from 53% to 100%.101-106 Ross et al.105 found that 68% of clients attending an outpatient treatment facility in Toronto qualified for a concurrent psychiatric diagnosis; the most common being antisocial personality, phobia, anxiety, and depression.
There is wide variability in the prevalence estimates derived from both community samples and from treatment populations. The variability comes from such factors as:
It is very difficult to disentangle the relationship between a substance use disorder and a mental health disorder from the perspective of
"what caused what". This makes it difficult to draw firm conclusions about the causal role of either substance use or mental health disorders in determining the course of either single or concurrent disorders, and the influence of various factors on long-term recovery.
Given the difficulty in establishing antecedents and consequences in much of the research, it is safer to speak of issues of association rather than causality. As noted by Drake and colleagues in a recent review,35 it was two decades ago when the high rate of substance abuse among young people with schizophrenia began to be seen as a factor complicating community adjustment.107-109 Since then, research has shown that concurrent disorders are associated with:
Outcomes associated with mental health treatment and ongoing community support seem to be negatively affected by co-occurring substance abuse.126 In particular, there is a strong association between poor outcomes for schizophrenic patients and the combined influence of medication compliance/non-compliance, current substance abuse and lack of outpatient contact.127 The converse also appears to be the case with the outcome of substance abuse treatment which is significantly and negatively associated with psychiatric impairment (or at least generalized psychological distress).128 This seems to be particularly the case among opiate, alcohol and cocaine abuse populations.129-131 Co-existing mental disorders increase the probability of abandoning treatment prematurely;130,132-136 which in turn negatively influences treatment outcome.137,138 Early dropout from treatment can be explained by the fact that many of these clients encounter difficulties in engaging in treatment and establishing a therapeutic alliance.139-145 Treatment engagement and therapeutic alliance are interconnected since the beneficial effects of treatment are positively correlated with continuation in treatment.146-154 If they do remain in treatment, the amount of attention and the length of treatment required by these individuals often exceeds the services normally planned by the program.132 Given the higher risks of relapse, higher likelihood of re-entering more expensive services, and the high likelihood of leaving needed services prematurely, effective assessment and treatment of people with concurrent disorders could help reduce health, social and correctional service costs.
There is widespread agreement that individuals who have co-occurring mental health and substance use disorders have typically had to seek treatment and ongoing support from two very separate service delivery systems (see for example, Ridgely et al.27 and the TIP concurrent disorders protocol).24 This is particularly true for people with concurrent substance abuse and severe and persistent mental illness (Group 2) and many people with concurrent personality disorders (Group 3). Whether the issues are discussed from a U.S. perspective and some of the nuances of their health care system, or from the perspective of more universal access to Canadian health care, the same basic theme emerges about the historical separation of the two systems of care. Furthermore, most analysts agree that these historical barriers are at the heart of many of today's problems experienced by consumers with concurrent disorders who are trying to access help in the two systems.
Many factors account for the historical separation of the two systems. History, notwithstanding, it is generally agreed that having two systems of care for people with such an overlap in their constellation of needs has had more negative than positive effects on continuity of care and consumer outcomes.
Having two separate systems of care has usually meant parallel or sequential services being delivered across the two systems with little or no coordination and less than optimal outcomes. Poorer outcomes are thought to result from various systematic factors, including:
Examples of conflicting approaches to treatment are abstinence versus harm reduction goals, and philosophical differences in the use of confrontational techniques (abstinence goals and confrontation being more common in some substance abuse treatment settings). The acceptability of psychoactive medication that helps manage the symptoms of mental illness also remains controversial in some substance abuse treatment settings.
In the worst case scenarios, the delivery of services across the two separate systems of care and support has meant the individual, and often the person with the most severe constellation of problems, has simply been referred across to the 'other side'. Such referral has also typically meant little or no case management, to ensure contact has been made, and that the person has been successfully engaged in the system. Dropout rates from concurrent treatment programs that are not well coordinated can run as high as 60%.157 Thus, high attrition from programs can be seen from the perspective of the low accessibility and acceptability of the services being offered. These concerns about poor coordination are echoed in research studies that have examined the coordination of services across mental health and substance abuse services and potential solutions.155 These issues are also quite salient in testimonials and personal stories of consumers participating in community system-level planning exercise,31 including the focus groups held for the current project (see Section 4.2.1).
In summary, there is a very strong rationale for the development of the best practice guidelines: