Addiction and Mental Illness

Research Update: Co-existing Disorders Make Recovery More Difficult

The following is a Research Update excerpt from the Butler Center for Research. Download the PDF to read the entire Update. 

People with alcohol or other drug disorders often suffer from co-existing mental health disorders. These are referred to as "dual disorders," "comorbid disorders," "MICA" (mentally ill chemical abusers), or substance abusers with "SMI" (serious mental illness). Regardless of what it is called, we know that this combination makes recovery from both disorders more difficult.1


At least 10 million people in the United States suffer from both alcohol/drug problems and mental illness.1 Prevalence is determined by surveys of the general population, and by diagnostic studies of people in treatment for alcohol/drug dependency or mental illness. While the prevalence of substance use disorders in the general population is about 16%, almost twice as many (29%) people with mental disorders have a substance use disorder. The rates of substance use disorders are particularly high for some diagnostic subgroups. For example, 47% of people with schizophrenia and 56% of people with bipolar disorders have a substance use disorder.2

Depression is often found at high levels among alcoholics and addicts seeking substance dependency treatment. As many as 80% of alcoholics experience depressive symptoms at some time in their lives, and 30% meet diagnostic criteria for major depression. Alcoholics are more likely to have bipolar disorders than the general population (3% vs. 1%).3 There is also a strong correlation between substance use disorders and Post-Traumatic Stress Syndrome (PTSD), with as many as one-third of patients meeting criteria for PTSD when they enter treatment for their alcohol/drug problems.4

Rates of other anxiety disorders, such as agoraphobia, panic disorder, social phobias and general anxiety disorders are high in treatment populations, ranging from 10%–60%4,5 but many of these may be substance-induced. Eating disorders, particularly bulimia, are common among people with alcohol and drug problems, especially women. Most studies find that between 15–32% of women with alcohol/drug disorders meet diagnostic criteria for an eating disorder at some time in their lives. Similarly, among bulimics, the rate of alcohol abuse or dependence is between 14–49%, and the rate of other drug abuse or dependence ranges from 8 to 36%.6

The relationship between Attention Deficit Hyperactivity Disorder (ADHD) and substance use disorders appears to be especially complex. Some studies show a higher rate of ADHD among substance abusers and that people with ADHD may develop substance use problems at an earlier age.7 Antisocial personality is associated with earlier onset and a more severe course of alcohol and drug problems.8

Why do these disorders occur together?

There are several theories to explain why substance dependency disorders and mental illnesses occur together so frequently. Researchers at the New Hampshire-Dartmouth Psychiatric Research Center put forth several, including the following:8

Self-medication theory: people use alcohol or drugs to quell disturbing symptoms of mental illness.

There are two problems with this theory: (1) There is no correlation between diagnosis and drug of choice. For example, depressed people do not tend to choose cocaine or other stimulants, people dealing with rage or aggression don't seem to choose heroin. (2) Self-report differs from actuality. For example, some studies that examine the relationship between stress and pain have found that the stress or pain may begin before the first symptoms of alcohol/drug problems.8, 9

Alcohol/drug use problems cause mental illness: There is some support for the idea that some drugs, particularly marijuana and hallucinogens may precipitate an earlier onset of mental illness in certain individuals who are already vulnerable. For example, people with apparent substance-induced mental illness have stronger family histories of mental illness than individuals with only substance use disorders.8

Chronic high use of alcohol, sedatives, and tranquilizers causes dysphoria, which may be mistaken as depression.10

A common factor causes both alcohol/ drug problems and mental illness: Genetic predisposition or a poor environment may cause both substance use problems and mental illness. Surprisingly, most genetic studies so far have not discovered a link between substance use disorders and mental illnesses, even for those disorders where the relationship appears to be quite strong, such as schizophrenia and bipolar illnesses.8 It may be that environmental factors are more salient. Poor social skills, social isolation, poor cognitive skills, lack of structure, poverty, lack of adult role responsibilities all provide fertile ground for development of both substance abuse problems and mental health problems. Or, it may be that the genetic factors, and their interaction with environmental factors, are so complex we cannot yet understand them.

Supersensitivity model: People with mental illnesses may be more susceptible to the harmful effects of alcohol and drugs.8 For example, it appears that at least 50% of the general population can drink alcohol without developing problems, but only 5% of schizophrenics can drink without developing problems. And people with schizophrenia appear to have a much harder time recovering from alcohol/drug problems: they have more relapses and spend more time in the hospital than non-schizophrenics, even though their severity level is the same.

Coexisting Disorders are of Special Concern

People with dual diagnoses face especially difficult lives. The complexity of their problems may not be assessed. Substance use disorders and mental health problems may both be overlooked by primary health care providers. Mental health providers may miss alcohol and drug problems; alcohol/drug treatment providers may miss mental health issues. People with co-occurring disorders are at particularly high risk for incarceration, homelessness, HIV infection, and other negative consequences of their disorders.1

Co-occurring disorders can be difficult to diagnose as the presence of one disorder interferes with the diagnosis of the other.

In mental health settings where mental illness is the emphasis, it is easy to miss alcohol and drug problems because of denial and the unreliability of self-report, especially during brief assessment procedures. Signs that may suggest a concomitant alcohol/drug problem in the severely mentally ill may not be directly alcohol/drug related, and instead may be suggested in increased appearance of symptoms, disruptive behavior, housing instability, and treatment non-compliance.11

Any alcohol or drug use among severely mentally ill people is of concern because of the chemical interaction with psychotropic medications, decrease in compliance with mental behavior such as unsafe sex.12

Mental illness may interfere with successful recovery from alcohol and drug problems. Some studies have found that people with ADHD13 and PTSD have poorer outcome rates after alcohol/drug treatment.4 Some treatment approaches used in alcohol/drug treatment, such as confrontation, produce decompensation in schizophrenics. Cognitive deficits and social impairment make recovery difficult for the severely mentally ill.

Techniques such as special case management during treatment or contingency management may improve treatment outcomes.12 Traditional Twelve Step groups and approaches can be modified to meet the needs of dually disordered patients.14 In fact, many cities have "double trouble" AA meetings to accommodate individuals with dual disorders.

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