SAMHSA logo Report to Congress - Nov 2002








Substance Abuse and Mental Health Services Administration
U.S. Department of Health and Human Services

Chapter 1 - Characteristics and Needs of the Population - Understanding Co-Occurring Disorders


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For Laurie Gable, it's all about recovery, from drugs and alcohol - 7 years plus - and from attention deficit disorder, on a daily basis. "I am in recovery, but for today I consider myself recovered," she says.

Ms. Gable, 46, coordinates projects funded by the CSAT Recovery Community Support Program at Easy Does It Inc., a transitional housing program in Leesport, Pennsylvania for people in early recovery. "I believe I was born addicted," she says. Further, she was caught up in the 1960s spirit of drugs and sex. "It was part of my passage into young adulthood," she notes. Later, as a young married mother, Ms.Gable took a night job. Stopping by the bar after a shift seemed natural.

"It began with a little beer and within a year I lost everything-my home, my kids, my husband," Ms. Gable says. She later became addicted to cocaine. She spent 17 days in a residential program and has been clean since. But another disorder lurked for 5 years.

"I was at a conference on attention deficit disorder and all of a sudden I said, `That's me.' What I heard was that people with ADD are calmed by cocaine," Ms. Gable says. "Cocaine made me normal, while it made other people very, very high."

To deal with the ADD, she keeps a close eye on her habits, moods, and pace, and takes time off to regroup when necessary. Self-care fits with her recovery from her addictions. "The most important aspect of my recovery is my faith," Ms. Gable says.


Understanding Co-Occurring Disorders

Co-occurring substance abuse disorders and mental disorders1 are both common and highly complex phenomena that have been estimated to affect from 7 to 10 million adult Americans in any one year (U.S. DHHS, 1999b; SAMHSA National Advisory Council, 1998). Children, youth, and older adults also may experience co-occurring substance abuse disorders and mental disorders. According to the U.S. Surgeon General in the 1999 report on mental health: "Forty-one to 65 percent of individuals with a lifetime substance abuse disorder also have a lifetime history of at least one mental disorder, and about 51 percent of those with one or more lifetime mental disorders also have a lifetime history of at least one substance abuse disorder" (U.S. DHHS, 1999b). Although limited co-occurring prevalence information is available on older adults, it is known that like their younger counterparts, older adults with mental disorders may be especially prone to the adverse effects of drugs or alcohol. The presence of severe mental illness may create additional biological vulnerability so that even small amounts of psychoactive substances may have adverse consequences for individuals with schizophrenia and other brain disorders (Drake et al., 1989).

Using the Term "Co-Occurring Disorders"

Co-occurring disorders have been called many other terms over the years, and many of these are still in use in the literature and in the field. While some of these terms represent an attempt to identify which problem or disorder is seen as primary or more severe (CSAT, in press), many have been criticized for insufficient specificity, accuracy, and sensitivity (Osher and Drake, 1996). They include: mentally ill chemically addicted (MICA); chemically abusing mentally ill (CAMI); mentally ill substance abuser (MISA); substance abusing mentally ill (SAMI); mentally ill chemically dependent (MICD); co-occurring addictive and mental disorders (COAMD); dually diagnosed; dually disordered; and addiction and co-occurring disorders (ACD).

More recently, the research literature has seen the growing use of the term "dual diagnosis." Drake and Wallach (2000), however, argue that this term is an "unfortunate misnomer." First, the term has been used to refer to people with other combination of illnesses, such as individuals with mental illness and developmental disabilities. Second, individuals rarely experience only two disorders. Rather, they have "multiple interacting disabilities, psychosocial problems, and disadvantages" (Drake and Wallach, 2000).

Drake and Wallach (2000) also posit that the use of the term "dual diagnosis" tends to ignore the broad range of psychosocial issues that are interrelated with co-occurring substance abuse disorders and mental disorders - issues such as risk and protective factors at the levels of family, community, and society. Such issues become important since, as with other chronic illnesses, co-occurring substance abuse disorders and mental disorders need to be monitored and reassessed on a regular basis to promote recovery and prevent relapse despite an individual's changing life circumstances and ongoing risk and protective factors.

Defining "Co-Occurring Disorders"

This report defines "co-occurring disorders" consistent with the definition developed by the expert consensus panel that crafted SAMHSA's revised Treatment Improvement Protocol (TIP), Substance Abuse Treatment for Persons with Co-Occurring Disorders (CSAT, in press). According to the consensus panel, people with co-occurring substance abuse disorders and mental disorders are

individuals who have at least one mental disorder as well as an alcohol or drug use disorder. While these disorders may interact differently in any one person (e.g., an episode of depression may trigger a relapse into alcohol abuse, or cocaine use may exacerbate schizophrenic symptoms), at least one disorder of each type can be diagnosed independently of the other.

The panel observed that while some individuals' mental health problems may be sub-clinical and not meet DSM-IV criteria for a specific mental disorder, such individuals may still benefit from the full range of services available to those whose conditions meet the DSM-IV criteria for co-occurring substance abuse disorders and mental disorders. The same may be true for those individuals who may have transitory conditions such as substance-induced mood swings (CSAT, in press).

Co-occurring disorders may vary among individuals, and in the same individual over time. Both disorders can vary along the dimensions of severity, chronicity, and degree of impairment in functioning. Both disorders may be severe or mild, or one may be more severe than the other. Either or both disorders may reflect episodes of acute symptom exacerbations or a chronic condition and may change over time. (CSAT, 1994)

Co-occurring disorders may include any combination of two or more substance abuse disorders and mental disorders identified in the Diagnostic and Statistical Manual of Mental Disorders - IV (DSM-IV). There are no specific combinations of substance abuse disorders and mental disorders that are defined uniquely as co-occurring disorders. As Osher (2001) notes, "Any drug of abuse may combine with any mental disorder to produce a wide range of symptoms and disability." For example, co-occurring substance abuse disorders and mental disorders may include major depression with cocaine dependence, alcohol abuse with panic disorder, alcohol and poly-drug abuse with schizophrenia, and borderline personality disorder with episodic poly-drug use (CSAT, 1994). Drake and Wallach (2000) point out that "the population of persons with co-occurring mental illness and substance use disorders...includes individuals with less disabling mental illnesses such as anxiety disorders, those with different severe illnesses such as schizophrenia and bipolar disorder, and those with either substance abuse or substance dependence." Thus, the range of disorders may vary widely among people with co-occurring substance abuse disorders and mental disorders. In addition, substance abuse and mental health problems (such as binge drinking by people with mental disorders) that do not reach the diagnostic threshold also are part of the co-occurring disorders landscape - problems that may offer opportunities for early intervention.

How Many People Have Co-Occurring Disorders?

A significant lack of prevalence data on co-occurring disorders exists. The best data available on the prevalence of co-occurring substance abuse disorders and mental disorders are derived from two extensive surveys conducted and analyzed over the past two decades: the Epidemiologic Catchment Area (ECA) Survey, initially administered in the period 1980 to 1984 (Regier et al., 1990), and the National Comorbidity Survey (NCS), administered between 1990 and 1992 (Kessler et al., 1994). Both surveys document high prevalence rates for co-occurring substance abuse disorders and mental disorders in the general population 2.

The ECA Survey focused on five geographical areas and assessed substance abuse disorders and mental disorders in more than 20,000 people living in the community and in various institutional settings, such as psychiatric hospitals, nursing homes, and jails or prisons. It provided the Nation's first quantitative information on co-occurring disorders. Because this report to Congress focuses heavily on annual prevalence rates, it relies somewhat more heavily on the more recent NCS data.

The NCS, a nationally representative, face-to-face household survey carried out between 1990 and 1992, was designed to build upon the results of the ECA Survey. The NCS estimates are based on a stratified, multistage area probability study of people age 15 to 54 years in the non-institutionalized population. The survey examined prevalence rates for co-occurring substance abuse disorders and mental disorders, as well as the temporal relationship between these disorders and the extent to which 12-month co-occurrence is associated with service utilization (Kessler et al., 1996).

Results of the NCS support the high prevalence rates for co-occurring substance abuse disorders and mental disorders among the general population described in the ECA Survey. The results also confirm the increased risk for people with either a substance abuse disorder or mental disorder for developing a co-occurring disorder. The NCS found that:

42.7 percent of individuals with a 12-month addictive disorder had at least one 12-month mental disorder.

14.7 percent of individuals with a 12-month mental disorder had at least one 12-month addictive disorder.

The ECA Survey found that individuals with severe mental disorders were at significant risk for developing a substance use disorder during their lifetime. In particular:

47 percent of individuals with schizophrenia also had a substance abuse disorder (more than four times as likely as the general population).

61 percent of individuals with bi-polar disorder also had a substance abuse disorder (more than five times as likely as the general population).

Estimates from both studies reveal that during a 12-month period, 22 to 23 percent of the U.S. adult population - 44 million people - have diagnosable mental disorders (U.S. DHHS, 1999b). About 15 percent (approximately 6.6 million) of adults with a diagnosable mental disorder have a co-occurring substance abuse disorder. More specific findings follow, along with some initial data from the National Comorbidity Survey Replication (NCS-R).

The reader is cautioned, however, that these prevalence studies are based on data that was collected between 15 and 25 years ago. Within the next year, the NCS-R, now underway, will provide new and more current estimates for adults and adolescents that are both comprehensive and more refined. New estimates based on the replication are expected to be closer to the lower end of the 7 to 10 million adults range (U.S. DHHS, 1999bb; SAMHSA National Advisory Council, 1998) found in previous studies. The replication relies on the classification and description of disorders found in the fourth edition of the American Psychiatric Association's Diagnostic and Statistical Manual (DSM-IV; American Psychiatric Association, 1994), which has more restrictive diagnostic criteria than the earlier manual, DSM-III-R, the nosology of which was utilized in the original NCS study. Balanced against these changes, however, is the continuing growth of the U.S. population, which will tend to increase the estimates.

The 2001 National Household Survey on Drug Abuse (NHSDA), for the first time in the Survey's history, included questions for adults and youth that measure serious mental illness (SAMHSA, 2002e). The survey found a strong relationship between substance abuse disorders and mental problems. Results are based on a scientific sample of the Nation's civilian non-institutional population and can be generalized to this population. As such, it does not include individuals in long-term institutions such as prisons and State mental hospitals.

According to the NHSDA, in 2001 there were an estimated 14.8 million adults age 18 or older with serious mental illness (SMI).3 This represents 7.3 percent of all adults. Of those with SMI, 6.9 million received mental health treatment in the 12 months prior to the interview. Among adults with SMI, 20.3 percent were dependent on or abused alcohol or illicit drugs; the rate among adults without SMI was 6.3 percent. An estimated 3 million adults had both SMI and substance abuse or dependence problems during the year.

Overall, an estimated 16.6 million persons age 12 or older were classified with dependence on or abuse of either alcohol or illicit drugs in 2001 (7.3 percent of the population). Of these, 2.4 million were classified with dependence or abuse of both alcohol and illicit drugs, 3.2 million were dependent or abused illicit drugs but not alcohol, and 11 million were dependent on or abused alcohol but not illicit drugs. In the 12 months preceding the NHSDA interview, an estimated 3.1 million persons age 12 or older (1.4 percent of the population) received some kind of treatment for a problem related to the use of alcohol or illicit drugs. Of this number, 1.6 million received treatment through a self-help group. An estimated 6.1 million persons age 12 or older needed treatment for an illicit drug problem in 2001. During the same period, 1.1 million persons received treatment for this problem at a specialty facility. However, overall the number of persons needing but not receiving treatment was estimated at 5 million. Of the 5 million people who needed but did not receive treatment in 2001, an estimated 377,000 reported that they felt they needed treatment for their drug problem. This includes an estimated 101,000 who reported that they made an effort but were unable to get treatment and 276,000 who reported making no effort to get treatment.

Children and Adolescents. The presence of co-occurring substance abuse disorders and mental disorders is not limited to adults. A substantial number of children and adolescents also experience substance abuse disorders, mental disorders, or co-occurring disorders. A study of mental health service use among youth reveals that nearly 43 percent of youth who receive mental health services in the United States have been diagnosed with a co-occurring disorder (CMHS, 2001). Data from the NCS indicated that the median age of onset for a mental disorder was 11 (Kessler et al., 1996). In her study of a nationally representative sample of 12 to 17-year-olds, Greenblatt (2000) noted that substance use increases dramatically with youth in the 11 to 15 year age group. Moreover, tobacco dependence is a gateway drug for other substances and is also a gateway drug for co-occurring disorders (Lasser et al., 2000; Ziedonis 1995).

Researchers have found a link between mental/emotional and behavioral disorders and substance abuse disorders in youth. Data from the SAMHSA 1994-96 National Household Survey on Drug Abuse indicated that alcohol or illicit drug dependence was reported by approximately 13 percent of adolescents with significant emotional problems (SAMHSA, 1999).

Adolescent treatment studies conducted by SAMHSA's Center for Substance Abuse Treatment, likewise, show a high rate of emotional disorders, including behavioral problems, among adolescents entering substance abuse treatment, 62 percent for males and 83 percent for females (CSAT 1997-2002). This includes conduct disorders, attention deficit hyperactivity disorders, major depressive disorder, generalized anxiety disorder and post traumatic stress disorder; for these populations of adolescents, multiple problems are the norm.

The 2001 National Household Survey on Drug Abuse found that an estimated 4.3 million youths age 12 to 17 received treatment or counseling for emotional or behavioral problems in the prior 12 months. This represents 18.4 percent of this population and is significantly higher than the 14.6 percent estimate for 2000. The reason cited most often by youths for the latest mental health treatment session was "felt depressed" (44.9 percent of youths receiving treatment), followed by "breaking rules or acting out" (22.4 percent), and "thought about or tried suicide" (16.6 percent). The rate of mental health treatment among youth who used illicit drugs in the past year (26.2 percent) was higher than youths who did not use illicit drugs (16.3 percent) (SAMHSA, 2002e).

The likelihood that a child or adolescent with a mental disorder will develop a subsequent substance abuse disorder varies by the kind of mental disorder being experienced. Costello et al. (2000) found that adolescents with behavioral disorders (e.g., conduct disorder, attention deficit hyperactivity disorder) were most likely to develop substance abuse disorders. Adolescents with depression were four times as likely as those without to develop substance abuse disorders, and those with anxiety disorders were twice as likely to develop substance abuse disorders.

The literature provides little information on which groups of adolescents with mental disorders are at greater risk than others for developing a substance abuse disorder. However, Costello and colleagues found that the presence of multiple mental disorders accounted for much of the increased risk for developing a substance abuse disorder (Costello et al., 2000).

Data from the NCS indicate that the onset of a mental disorder may precede the substance abuse disorder. According to this survey, almost 90 percent of those with a lifetime co-occurring disorder had at least one mental disorder prior to the onset of a substance abuse disorder. Generally, the mental disorder occurred in early adolescence (median age 11), followed by the substance abuse disorder 5 to 10 years later (median age 21) (Kessler et al., 1996).

The time between the onset of a mental disorder and a subsequent substance abuse disorder represents an important "window of opportunity" in which a co-occurring disorder may be prevented (Ziedonis, 1995). It suggests not only the value of early diagnosis and treatment of mental disorders in youth, but also the critical role for alcohol and drug testing as important tools for prevention, early identification and intervention.

How Do People Develop Co-Occurring Disorders?

Researchers have offered explanations for high prevalence rates of substance abuse disorders among individuals with mental disorders but the etiology is not yet clear. Schuckit (NASMHPD/NASADAD, 1999) has outlined three ways in which substance abuse disorders and mental disorders may relate to one another: 1) the disorders may occur independent of each other; 2) the mental disorder may place an individual at greater risk for substance abuse disorders (e.g., schizophrenia and anti-social personality disorder); and 3) drug abuse intoxication or withdrawal may result in temporary mental disorder syndromes.

Mueser et al. (1998) reviewed two decades of etiological theories related to co-occurring substance abuse disorders and mental disorders. Based on that analysis, they offered 4 general models that synthesize current thinking in the field regarding the etiology of co-occurring substance abuse disorders and mental disorders (Anthony, 1991; Kosten and Ziedonis, 1997; Kushner and Mueser, 1993; Lehman et al., 1989; Meyer, 1986; Weiss and Collins, 1992):

Common factor models. High rates of co-morbidity are the result of risk factors 4 shared across both severe mental illness and substance abuse disorders.

Secondary substance abuse disorder models. Severe mental illness increases a person's chances of developing a substance abuse disorder.

Secondary mental/psychiatric disorder model. Substance abuse precipitates severe mental illness in people who would not otherwise develop a severe mental illness.

Bi-directional models. Either severe mental illness or substance abuse disorders can increase a person's vulnerability to developing the other disorder.

The researchers found modest support for a connection between antisocial personality disorders and increased comorbidity (an example of the common factor model), and for a secondary substance use model in which a person with a mental disorder is biologically vulnerable to develop a substance abuse disorder if they use even small amounts of alcohol or other drugs (Mueser et al., 1998). However, the lack of longitudinal assessment data limited evaluation of these models. Further, they noted that different models may account for co-occurrence in different people and that more than one model may apply to a given individual and that some of the models have not been examined systematically (Mueser et al., 1998).

For other individuals, substance abuse disorders may precede or precipitate the onset of a mental disorder. Data from one study reveal that mood and anxiety disorders diagnosed in individuals with a substance abuse disorder may be an artifact of their substance abuse and may improve with recovery from substance abuse (Verheul et al., 2000). This study found little support, however, for the theory that personality disorders also may be secondary to substance abuse.

Schuckit (1996) and Schuckit and Hesselbrock (1994) examined the relationship between lifelong alcohol dependence and anxiety disorders. They found that even though depressed or anxious people who also are alcohol dependent may believe they drink to relieve symptoms of sadness or nervousness, research does not unanimously support the contention that severe depressive or anxiety disorders are the usual cause of alcoholism (Schuckit, 1996). The researchers conclude that high rates of comorbidity of anxiety and alcoholism may reflect a mixture of true anxiety disorders along with temporary substance-induced anxiety syndromes (Schuckit and Hesselbrock, 1994).

RachBeisel and McDuff (1995) note that depression and psychosis may be precipitated by substance abuse. However, they caution that differentiating a substance-induced or secondary mental illness from a primary disorder is complex and imprecise. Chronic use of alcohol, opiates, and cocaine is the most common factor leading to depressive symptoms. Psychotic disorders have been identified as secondary to a wide variety of addictive substances, including PCP, crack cocaine, hallucinogens, alcohol, and ecstasy. The type of depression seen as secondary to substance abuse is similar to a primary depressive disorder, except the symptoms are likely to be mild to moderate rather than severe (RachBeisel and McDuff, 1995).

Suicide, associated with depression, is a serious concern for individuals with co-occurring disorders: 15 to 25 percent of suicides are committed by individuals who abuse alcohol, and between 5 and 27 percent of all deaths in individuals who abuse alcohol are due to suicide, compared to 1 percent in the general population (Jaffee and Ciraulo, 1986, in RachBeisel and McDuff, 1995). Psychotic episodes, including suicide, may be associated with intoxication or withdrawal from addictive substances, or may be a lasting result of chronic substance abuse. The 2000 National Household Survey on Drug Abuse reported that approximately 3 million youth age 12 to 17 thought seriously about suicide or attempted suicide in 2000. The data show that while 13.7 percent of youths aged 14 to 17 considered suicide in the past year, only 36 percent of those at risk children received mental health treatment or counseling. The data also reveal that youth who used alcohol or illicit drugs in the past year were more likely than other youths to consider taking their own lives. The likelihood of suicide risk was similar among white, black, Hispanic and Asian youth.

A growing body of research has implicated trauma - including past or current physical or sexual abuse - as a risk factor for the development and course of both substance abuse disorders and mental disorders. For example, between 51 and 97 percent of women with serious mental illnesses report some form of physical or sexual abuse during their lifetimes (Goodman, 1997). Among women in treatment for drug or alcohol disorder, 41 percent to 71 percent report being sexually abused as children or adults (Alexander, 1996). A more complete discussion of the role of trauma is presented in Chapter 4 of this report.

Despite strides in the research base over the past two decades, little remains known about the etiology and temporal ordering of co-occurring substance abuse disorders and mental disorders. For this reason, many researchers and clinicians believe that both disorders must be considered as primary and treated as such (Ridgely, Osher & Talbott, 1987; Minkoff, 1991; Drake, McLaughlin et al., 1991; Osher and Kofoed, 1989).

How Are People with Co-Occurring Disorders Receiving Treatment?

A report on the treatment experiences of youth with co-occurring substance abuse disorders and mental disorders states:

Tragically, youth with co-occurring substance abuse disorders and mental disorders and their families rarely get the kind of help they need at the time they need it. Services and supports are fragmented, isolated, and rigid (Federation of Families, 2000).

The discussion that follows summarizes data that confirm this observation, not just for youth, but for people of all ages who have co-occurring disorders. A history of treatment approaches for co-occurring disorders and barriers to providing appropriate care are highlighted in subsequent sections of this chapter.

Many Individuals Receive No Care or Inadequate Care.

Research has suggested that the vast majority of people with co-occurring substance abuse disorders and mental disorders do not receive care for a broad range of reasons. For example, severe under-funding of the public substance abuse and mental health treatment delivery systems has led to long waiting lists for care. At the same time, private insurance often excludes or severely limits coverage for services for people with either substance abuse disorders or mental disorders, a significant issue since both disorders can be chronic in nature, requiring long-term treatments, not dissimilar to the long-term needs of people experiencing diabetes, heart disease or stroke. Finally, the discrimination and stigma of substance abuse disorders and mental disorders may be isolating, making people with these disorders less likely to seek care in the first place.

The National Comorbidity Survey Replication. A total of 5,000 interviews have already been conducted for the NSC-R, out of a planned total of 10,000. The principal investigator, Ronald C. Kessler, has provided SAMHSA with new estimates based upon these cases, with the important caveat that preliminary results are incompletely weighted and based on the first half of the NCS-R survey.

The data from the NCS-R provide valuable information about service use (see Table 1.1 below). Of those with both substance dependence and serious mental illnesses, only 19 percent receive treatment for both disorders; 29 percent do not receive treatment for either problem. If treatment is received at all, it most often is for the mental disorder alone (49 percent).

Table 1.1
Rates of Treatment by Type (Mental Health, Substance Abuse) and
by Severity Level of the Disorder (NCS-R)

Level of Substance Abuse Disorder

Type of Treatment

Level of Mental Disorder

12-month serious mental illness

12-month other
mental illness

12-month substance dependence

Neither MH nor SA



MH only



SA only



Both MH and SA



12-month substance abuse

Neither MH nor SA



MH only



SA only



Both MH and SA



For people with less severe but still diagnosable mental illnesses and either substance dependence or substance abuse, the pattern is similar. Most receive no treatment (71 percent and 78 percent, respectively), and only a very few receive treatment for both disorders (4 percent and 3 percent, respectively). Once again, the most frequent treatment is for the mental disorder alone. As stated in the table and elsewhere in the report, there is a clear need and challenge to strengthen the training and resources in mental health treatment systems to use appropriate alcohol and drug testing tools in the diagnosis and treatment of patients with co-occurring disorders.

The Healthcare for Communities Survey. Data from the Healthcare for Communities Survey, conducted by UCLA and RAND, support the NCS-R findings. Among people with co-occurring disorders, this study found that 72 percent did not receive any mental health or substance abuse treatment over the previous year (Watkins et al., 2001). Fewer than 25 percent of individuals with co-occurring disorders received appropriate mental health services, and only 9 percent received supplemental substance abuse services.

Both the NCS-R and Healthcare for Communities Survey also found that individuals with a substance abuse disorder are more likely to receive treatment if they have a co-occurring mental disorder, suggesting that substance abuse disorders are left untreated more often than mental disorders. This is a matter of special concern because individuals with substance abuse disorders tend not to get better unless they receive treatment, and because the severity of the co-occurring mental disorder is predictive of substance abuse treatment outcomes among individuals with co-occurring disorders (McLellan et al., 1983; Drake et al., 1996).

Insurance Claims Data. Under SAMHSA sponsorship, a multi-organizational team of investigators analyzed rates of treatment of individuals with substance abuse disorders and/or mental disorders as represented in fee-for-service, health insurance claims data (Finkelstein et al., 2002a). They employed files from public insurance programs (Medicare and Medicaid in Michigan, New Jersey, Pennsylvania, and Washington) and from a sample of claims representing private insurance companies from the mid-1990s. The investigators found that between 7 and 9 percent of all enrollees had evidence of either a substance abuse disorder or a mental disorder or both. In contrast, rates of treatment among adults for both disorders are less than one percent, ranging from 0.2 to 0.9 percent.

The question arises as to whether these rates are higher, lower or about what would be expected. The actual prevalence rates for these disorders in these particular insurance programs are not known. However, it is known, for example, that the prevalence rate of co-occurring disorders in the general adult population is estimated to be 4.8 percent (Kessler et al., 1996). The rate in the Medicaid population, given the fact that people living in poverty are at increased risk for developing co-occurring disorders, is likely to be even higher. Thus, finding treatment rates of 0.2 to 0.9 percent for both disorders suggests that there are many fewer people in treatment than those who need it.

Veterans Affairs Data. Unlike other systems, the health care system operated by the Department of Veterans Affairs has high rates of identification of co-occurring disorders. Rosenheck and Greenberg (2002) reported that 44 percent of 72,252 inpatients treated during fiscal year 2001 had co-occurring substance abuse disorders and mental disorders. Among veterans receiving specialized treatment for post traumatic stress disorder, 41 percent had a co-occurring substance abuse disorder (Fontana et. al., 2002).

Individuals Who Receive Care in the Mental Health or Substance Abuse System

Individuals with co-occurring disorders who receive care are likely to be treated in the system to which they present themselves. Mental health service programs have assumed responsibility for comprehensive care, including substance abuse treatment, for individuals with serious mental illnesses (Drake, Essock et al., 2001). Substance abuse treatment programs care for large numbers of individuals who have co-occurring substance abuse disorders and mental disorders.

An analysis of State Alcohol and Drug Abuse Profile (SADAP) data reveals that in fiscal year 1999, 142,164 individuals were admitted to State-funded alcohol and drug abuse programs specifically for treatment of substance abuse disorder with a co-occurring mental disorder (NASADAD, 2002; emphasis original). SAMHSA's 1999 Uniform Facility Data Set (UFDS) indicates that in 1999, nearly half of all public and private facilities that provide substance abuse treatment offered services to individuals with co-occurring mental disorders. Thirty-eight percent of programs that focus primarily on substance abuse disorders reported offering services to people with co-occurring disorders. This survey does not reveal the specific types of services offered or the manner in which they were delivered (SAMHSA, 2002d). Services for co-occurring disorders were most likely to be offered by facilities operated by the U.S. Department of Veterans Affairs (73 percent), and by programs that provide treatment for both substance abuse disorders and mental disorders (67 percent).

Typically, individuals with co-occurring disorders who receive services through either the mental health or substance abuse treatment systems receive sequential treatment (treatment first from one provider, then another) or parallel treatment (treatment from two separate providers at the same time). Neither system has the capacity to provide both mental health and substance abuse treatment within a single program. Despite evidence in support of integrated treatment for substance abuse disorders and mental disorders, only 4 percent of individuals in the Healthcare for Communities Survey reported receiving sequential care (Watkins, et al., 2001). Another 4 percent reported receiving parallel treatment.

Fragmented and uncoordinated services create a service gap for persons with co-occurring disorders. This service gap led to a call by many clinicians, researchers, and consumers for the provision of treatment for people with co-occurring disorders in an integrated program where both the mental health services and substance abuse treatment could be provided by the same clinician or group of clinicians (e.g., Drake et al., 1995; Mueser et al., 1997), identified as integrated treatment. There is no need to create a separate system of care for people who have co-occurring substance abuse disorders and mental disorders (The National Council and SAAS, 2002; AACP, 2000; Osher, 1996; Ridgely et al., 1987).

Individuals Who Receive Care Outside of the Mental Health or Substance Abuse System

Recognizing that stigma is associated with substance abuse disorders and mental disorders, many individuals with co-occurring disorders seek treatment in primary care settings. However, when the mental health, substance abuse, or primary care setting does not meet the needs of an individual, that person risks becoming homeless

Primary Health Care. Individuals with co-occurring substance abuse disorders and mental disorders have high rates of other health problems and often present for care in the primary health care system. In fact, many individuals with mental disorders seek and receive care exclusively through the primary health care system (Gournay et al., 1997; Shapiro et al., 1984). There is little evidence that these disorders are identified or treated, or that the primary health and behavioral health care systems collaborate to deliver care effectively (Ridgely and Johnson, 2001). Data from the Medical Outcomes Study found evidence that primary care physicians often do not detect the presence of substance abuse disorders and mental disorders (Ford, 1994; Wells et al., 1989). This is especially true for older adults.

Homeless Services. Approximately 39 percent of people who are homeless have a mental disorder, and an estimated 50 percent of adults with serious mental illnesses who are homeless have a co-occurring substance abuse disorder (U.S. DHHS, 1999b; Lehman and Cordray, 1993; Ridgely & Dixon, 1993; Fisher and Breakey, 1991). Because individuals who are homeless are far less likely to use the traditional systems for receiving care (Burt et al., 1999), a broad range of community programs has emerged to address their substance abuse, mental health, housing and social support needs. Many of these programs are supported by Federal initiatives, such as the SAMHSA Projects for Assistance in Transition from Homelessness (PATH) program, the Health Resources and Services Administration (HRSA) Health Care for the Homeless Program, and the U.S. Department of Housing and Urban Development (HUD) Continuum of Care program.

Though these programs provide important, high quality and sometimes lifesaving services, they alone are not sufficient to provide fully adequate care for individuals who are homeless, including those with co-occurring disorders who are without a home, and who struggle with all of the conditions associated with a life of poverty (Osher and Dixon, 1995).

The Criminal Justice System. Epidemiological studies show the use of drugs or alcohol by people with untreated serious mental illnesses increases their potential for violent behaviors (IOM, 1999). One analysis suggests that substance abuse, psychotic symptoms, lack of contact with specialized community mental health services, and poor adherence to medication are all associated with greater risk of adult life-time violence (Swartz et al., 1998).

The criminal justice system, as a whole, has experienced substantial growth over the past decade with a 76 percent increase in the number of individuals incarcerated since 1990. Estimated rates of severe mental and substance abuse disorders in jail and prison populations range from 3 percent to 16 percent (Peters and Hill, 1993; Teplin, 1990; Steadman et al., 1987). Among detainees with mental disorders, 72 percent also have a co-occurring substance abuse disorder. In the juvenile justice system, preliminary data suggest that two-thirds of the 1 million youth who have formal contact with the justice system, or more than 670,000 youth, have one or more substance abuse disorders and mental disorders (OJJDP, 2001).

Studies have found that approximately one-third of adult male detainees and one-quarter of female detainees who needed services for severe mental disorders reported receiving treatment in jail. Fewer than 10 percent of Federal inmates who are addicted to drugs or alcohol have treatment available to them, despite the growing evidence demonstrating that intensive treatment in prison can reduce recidivism by one-half after release (CSAT, 1996).


1 For the purposes of this report "mental disorders" represent the continuum of psychiatric severity from less to more severe.

2 For purposes of estimating the annual prevalence rates of co-occurring disorders, epidemiologists typically assume that diagnostic criteria for specific disorders as defined by American Psychiatric Association's Diagnostic and Statistical Manual (DSM) must be met, and that the two disorders must occur within a 12-month time period.

3 Serious mental illness is defined as having a mental disorder that resulted in functional impairment within the past 12 months.

4 Risk factors, as described in detail in the "Prevention" chapter of this report, are factors such as low socioeconomic status or relationship loss and bereavement that increase an individual's, a group's, or a community's vulnerability to mental illness or substance abuse.



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