What is comorbidity?

Introduction

People with primary psychiatric disorders have high rates of substance abuse and addictive disorders and vice versa. These clinical conditions are defined in the
Diagnostic and Statistical Manual of Mental Disorders: DSM 5 (2013) of the American Psychiatric Association, which is the widely used nomenclature for mental disorders. In the fields of clinical psychology and psychiatry, the terms comorbidity or dual diagnosis, generally apply to the presence of one or more serious mental disorders (SMDs) and one or more substance use disorders (SUDs). However, comorbidity can also refer to the co-occurrence of two or more serious mental disorders such as personality disorders .

Prevalence

Substance use disorders and addictive disorders are the most common and clinically severe disorders that affect people with serious mental disorders, which include major depression, bipolar disorder, anxiety disorders, and schizophrenia. The Substance Abuse and Mental Health Services Administration reported in 2009 that almost 9 million adults in the United States have co-occurring mental and substance use disorders. Estimates of the percentages of people with both lifetime serious mental and substance use disorders vary among different studies. The Epidemiological Catchment Area Study, which involved structured psychiatric interviews with more than twenty thousand randomly selected participants, found that nearly half of those diagnosed with schizophrenia (48 percent) and more than half (56 percent) of those diagnosed with bipolar disorder had one or more substance use disorders.

Causes and Consequences

Significant research has been conducted to attempt to determine why serious mental and substance use disorders co-occur. Studies of close family members and twins have suggested an inherited susceptibility to serious mental and substance use disorders, and investigations are pointing to the potential for overlapping genetic vulnerabilities. A 2010 report from the National Institute on Drug Abuse (NIDA), a division of the US Department of Health and Human Services, indicated an individual's vulnerability to addiction is 40–60 percent genetic, and a more recent (2013) study in the journal Nature Genetics linked five major mental disorders—schizophrenia, bipolar disorder, major depressive disorder, autism spectrum disorders, and attention-deficit hyperactivity disorder (ADHD)—to the same genetic variations. Furthermore, specific areas of the brain, such as those that use the neurotransmitter dopamine are affected by addictive substances and are known to be involved in several mental illnesses such as schizophrenia and depression. NIDA also reported that individuals diagnosed with mood or anxiety disorders and antisocial syndromes, such as antisocial personality disorder and its childhood precursor conduct disorder, are almost twice as likely to suffer from substance use disorder. Conversely, those suffering from substance use disorder are about twice as likely to also suffer from mood and anxiety disorders. It is unknown whether substance use causes mental illness or if the presence of a serious mental illness contributes to substance use disorder.

Anecdotal evidence suggests that individuals with mental disorders such as anxiety or depression or with negative side effects from a psychopharmacological course of treatment use certain substances to self-medicate to alleviate their symptoms. For example, people with depressive disorders often choose drugs that have stimulating effects, such as cocaine or amphetamines. Conversely, people with anxiety-inducing disorders often choose drugs that have sedative effects, such as opiates or alcohol.

Research suggests that people who have a mental illness are hypersensitive to the effects of drugs and alcohol. Small amounts of drugs and alcohol in people with a mental illness, compared with individuals with no mental illness, are more likely to impair the person’s performance in cognitive and motor tasks. Furthermore, small amounts of drugs and alcohol can result in more abuse and dependence problems, as well as other negative consequences, for mentally ill individuals than for those who are not mentally ill.

Treatment Options

Comorbid disorders differ from single disorders in their clinical courses and treatment protocols. Individuals with comorbidity are generally more difficult to diagnose and treat, primarily because of the similarities between the symptoms of substance use disorder and major mental illnesses. Individuals with comorbidity often experience a greater number of psychotic symptoms, require more specialized and intensive treatment, and have poorer treatment outcomes than those with only a serious mental or substance use disorder. People with dual diagnoses also have more difficulty accessing treatment. According to 2009 report from the Substance Abuse and Mental Health Services Administration, only 7.4 percent of individuals with co-occurring disorders receive treatment for both conditions with 55.8 percent receiving no treatment at all.

Treatment programs for people with serious mental or substance use disorders have historically been administered through separate systems with different criteria for client services and different training, education, and certification requirements for service providers. Individuals with comorbidity usually have participated in sequential treatment in which they are expected to be free of either their serious mental or substance use disorder before receiving treatment for the other disorder. Another option is for such individuals to receive parallel treatment, thus participating in both treatments simultaneously but with different practitioners who work at different agencies or clinics.

Sequential and parallel treatments have led to fragmented and ineffective care for people with dual diagnoses. Such treatments force them to navigate the mental health and substance abuse systems separately and to struggle with the disparate messages that they receive from each about treatment goals and pathways to recovery. For example, many drug treatment programs prohibit patients from taking psychiatric medications, the mainstay of care for people with serious mental illness.

Integrated treatments for co-occurring disorders are delivered by professionals who view both serious mental and substance use disorders as “primary” conditions, provide coordinated care for co-occurring disorders, and adhere to consistent and shared philosophies and treatment plans. The essential ingredients of integrated treatments for people with comorbidity include assertive outreach procedures; case management models; comprehensive services; shared decision making with staff, clients, and clients’ families; progressive stages that engage clients in treatment and help them avoid relapses; team approaches to service delivery; long-term commitment to services; cross-training for program staff; and the use of self-help groups and psychopharmacological interventions.

Integrated treatment for co-occurring disorders is more effective than either sequential or parallel treatments. Studies have found that people with co-occurring disorders who are in integrated treatment programs have sustained remission rates from substance use that are two to four times higher than those in nonintegrated treatment programs. Other benefits of integrated treatment for comorbidity include longer retention in treatment, lower rates of victimization, and less time in the hospital. The treatment dropout rates of people with dual diagnoses are very high, owing to their low motivation, cognitive impairment, and disorganized lives. Therefore, clinicians in integrated programs concentrate their services in the community, aggressively bringing comprehensive services to clients rather than expecting clients to seek such services. Comprehensive services encompass all areas of clients’ lives and are aimed at improving their potential for obtaining employment, having stable housing, and living independently.

Treatment plans are more readily accepted and adhered to when people with comorbidity—and their families—have a role in developing and modifying such plans. Moreover, systematic or stage-wise models to treatment recognize that clients must be engaged in services, be motivated to change, be helped to achieve abstinence, and be taught to prevent relapses from serious mental and substance use disorders. Medications for serious mental and substance use disorders are instrumental in reducing and managing symptoms. If left untreated or treated with nonintegrated approaches, co-occurring serious mental and substance use disorders usually become more severe and chronic. People with dual diagnoses need considerable time to recover. Hence, integrated programs take a long-term view of success with such patients.

People with comorbidity are common in both the mental health and substance abuse treatment systems and in the criminal justice system. They present significant challenges to treatment providers and place tremendous strain on resources. Patients with dual disorders suffer from a wide range of public health problems and are unlikely to recover without long-term care. Offenders with comorbid serious mental and substance use disorders are more likely to recidivate, engage in violent behaviors, and have infectious diseases. Integrated programs have the best chance of helping them achieve more satisfying and productive lives.

The War on Drugs in the United States has swelled the country’s probation, jail, and prison populations with unprecedented numbers of drug-abusing and drug-dependent offenders, and has lead to the implementation and evaluation of numerous drug treatment programs in correctional settings. Lost in the emphasis on providing drug treatment to offenders, however, is the very high rates of comorbid psychiatric disorders. The lack of specific programs for offenders with co-occurring disorders has resulted in high rates of rearrests and reincarcerations and has increased the likelihood of violent behaviors within this population.

Although the nation’s correctional populations continue to grow, adequate and well-designed treatment programs are needed more urgently than ever to address psychiatric comorbidities among offender populations. Despite high rates of psychiatric comorbidity among offender populations, drug treatment programs in criminal justice settings and the general community have concentrated on drug treatment and have failed to address psychiatric comorbidity adequately. Unfortunately for those with comorbidity, not enough effective programs are available to meet the demand for such care.

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