National Institute on Alcohol Abuse and Alcoholism No. 14 PH 302 October 1991

Alcoholism and Co-occurring Disorders

The term "comorbidity" refers to the presence of any two or more illnesses in the same person. These illnesses can be medical or psychiatric conditions, as well as drug use disorders, including alcoholism. Comorbid illnesses may occur simultaneously or sequentially. The fact that two illnesses are comorbid, however, does not necessarily imply that one is the cause of the other, even if one occurs first.

An understanding of comorbidity is essential in developing effective treatment and prevention efforts. For example, since alcoholism causes liver disease, measures to decrease alcohol consumption will help reduce the incidence of liver disease. With respect to treatment, persons exhibiting comorbid alcohol-related and medical or psychiatric disorders often fall through the cracks of the health care system because of administrative distinctions among addiction, medical, and mental health-related services. Patients are often forced to choose between clinical settings, often resulting in neglect of one condition (1).

Alcoholism and other disorders might be related in a number of ways, including the following (2,3): 1) Alcoholism and a second disorder can co-occur, either sequentially or simultaneously, by coincidence. 2) Alcoholism can cause various medical and psychiatric conditions or increase their severity. 3) Comorbid disorders might cause alcoholism or increase its severity. 4) Both alcoholism and the comorbid disorder may be caused, separately, by some third condition. 5) Alcohol use or alcohol withdrawal can produce symptoms that mimic those of an independent psychiatric disorder.

Research on the nature of the relationship between comorbid disorders generally relies on surveys of either the clinical population (persons in treatment) or the general population. Most studies of comorbidity are based on clinical samples. This may result in inflated estimates of comorbidity, since persons with multiple ailments may be more likely to seek treatment (Berkson's fallacy) (4). This trend may be countered to some extent by the reluctance of some alcoholism treatment centers to admit persons exhibiting serious psychiatric problems. Thus, the prevalence of comorbid psychiatric disorders among alcoholics in treatment does not reflect the actual prevalence of such comorbidity in the community (3).

Additional methodological difficulties complicate both clinical and general population investigations. For example, estimates of comorbidity will also vary depending on how alcohol use disorders are defined. Definitions of alcoholism have included 1) formal definitions of abuse and dependence appearing in psychi atric classification systems such as the DSM-III-R; 2) alcohol-related symptom ratings; 3) serious manifestations of physiological dependence (i.e., tolerance and withdrawal); and 4) various levels of heavy alcohol consumption. Since alcohol use, alcohol withdrawal, and alcohol abuse and dependence may each relate to comorbid conditions in an entirely different way, it is essential when evaluating comorbidity to clarify which aspects of alcohol use are involved (5). Similar considerations apply to the evaluation of comorbid disorders. For example, when evaluating depression, it is important to distinguish among sadness, grief, and major depressive disorder (2).

An important source of comorbidity data is the Epidemiologic Catchment Area (ECA) program of the National Institute of Mental Health (6). The ECA surveyed more than 20,000 respondents residing in households, group homes, and long-term institutions in five sites across the United States (7) to provide data about the prevalence and incidence of psychiatric dis orders, as well as issues related to treatment. (Prevalence is the number of existing cases; incidence is the number of new cases.)

Conclusions about causal relationships between alcohol use disorders and comorbid psychiatric disorders based on ECA data are problematic, since sequencing criteria consisted of age at first symptom of the alcohol use disorder, rather than age at onset of the syndrome (8). Moreover, the ECA program defined alcohol use disorders as the occurrence of enough symptoms to meet the associated diagnostic criteria over the life course. The sporadic occurrence of isolated symptoms, perhaps years apart, provides an insufficient basis for testing competing hypotheses related to comorbidity.

Because the term "comorbidity" is often not applied to medical conditions, a number of medical conditions that are often comorbid with alcoholism are mentioned below. A discussion of comorbidity with psychiatric disorders will follow.

Medical conditions. Alcohol has been shown to be directly toxic to the liver. Approximately 90 to 100 percent of heavy drinkers show evidence of fatty liver, an estimated 10 to 35 percent develop alcoholic hepatitis, and 10 to 20 percent develop cirrhosis (9). Fatty liver is reversible with abstinence, alcoholic hepatitis is usually reversible upon abstinence, and while alcoholic cirrhosis is often progressive and fatal, it can stabilize with abstinence (10). In addition to liver disease, heavy alcohol consumption causes chronic pancreatitis (11) and malabsorption of nutrients (12).

The prevalence of alcoholic cardiomyopathy (heart muscle disease) is unknown. Alcohol-induced heart damage appears to increase with lifetime dose of alcohol (13).

Alcohol can damage the brain in many ways. The most serious effect is Korsakoff's syndrome, characterized in part by an inability to remember recent events or to learn new information. The incidence of alcohol-related brain damage is approximately 10 percent of adult dementias in the United States (14). Milder attention and memory deficits may improve gradually with abstinence (15).

Additional diseases strongly linked to alcohol consumption include failure of reproductive function (10) and cancers of the mouth, larynx, and esophagus (16). Hospitalized alcoholics have also been found to have an increased prevalence of dental problems, compared with nonalcoholic psychiatric patients, including missing teeth and nonrestorable teeth (17).

Psychiatric disorders. Despite the study's shortcomings, data from the ECA provide a starting point for assessing the prevalence of some comorbidities (on a lifetime basis). Based on ECA data, alcoholics are 21.0 times more likely to also have a diagnosis of antisocial personality disorder compared with nonalcoholics. Similar "odds ratios" for some other psychiatric comorbidities are as follows: drug abuse, 3.9 times; mania, 6.2 times; and schizophrenia, 4.0 times. There is only a mild increase in major depressive disorder among alcoholics (odds ratio 1.7), and essentially no increase in anxiety disorders (18).

Antisocial personality disorder. The strongest correlate of alcoholism documented in the ECA is antisocial personality disorder (ASPD) (18). Determining the chronological relationships between the two disorders is complicated by the following factors (3,19,20): 1) both disorders typically begin early in life, thus requiring retrospective reporting from adults; 2) there is considerable overlap in the symptoms of the two disorders; 3) alcohol or other drug abuse is itself one of the diagnostic criteria for ASPD; and 4) intoxication leads to behavioral disinhibition, thus lowering the threshold for antisocial behavior (20).

Comorbid ASPD has prognostic and treatment implications for alcoholics. Patients with ASPD have an earlier age of onset of alcohol and other drug abuse and a more rapid and serious course of illness (21,22, 23,24).

Bulimia. Bulimia is an eating disorder in which patients, usually female, binge on sugar- and fat-rich meals, and purge regularly, as by self-induced vomiting. This disorder is characterized by craving, preoccupation with binge eating, loss of control during binges, an emphasis on short-term gratification, and ambivalence about treatment--symptoms that resemble those of addictive disorders (19,25). Bulimics commonly exhibit multiple drug use disorders and have high rates of alcoholism. Between 33 and 83 percent of bulimics may have a first-degree relative suffering from alcohol abuse or alcoholism (25).

Depression. Although it has been suggested that alcoholism and depression are manifestations of the same underlying illness, the results of family, twin, and adoption studies suggest that alcoholism and mood disorder are probably distinct illnesses with different prognoses and treatments (1,2). However, symptoms of depression are likely to develop during the course of alcoholism, and some patients with mood disorders may increase their drinking when undergoing a mood change, fulfilling criteria for secondary alcoholism. When depressive symptoms are secondary to alcoholism, they are likely to disappear within a few days or weeks of abstinence, as withdrawal symptoms subside (2,15,26,27).

Anxiety. Studies (not using ECA data) indicate that approximately 10 to 30 percent of alcoholics have panic disorder, and about 20 percent of persons with anxiety disorders abuse alcohol (28). Among alcoholics entering treatment, about two-thirds have symptoms that resemble anxiety disorders (29). The relation between major anxiety disorders and alcoholism is unclear (30). Several studies indicate that anxious patients may use alcohol or other drugs to self-medicate, despite the fact that such use may ultimately exacerbate their clinical condition (28).

The strongest correlation between alcoholism and severe anxiety symptoms occurs in the context of alcohol withdrawal (30). The severe tremors, feelings of tension, restlessness, and insomnia associated with withdrawal begin to subside after 4 or 5 days, although a vulnerability to panic attacks and to generalized anxiety may continue for months. Because these symptoms decrease with abstinence, they are unlikely to represent an independent anxiety disorder (30). Interestingly, subjects suffering from both alcoholism and panic disorder are unable to distinguish between a number of symptoms common to both disorders (31).

Other drug abuse. Based on ECA data (18), alcoholics are 35 times more likely than nonalcoholics to also use cocaine. Similar odds ratios for other types of drugs are: sedatives, 17.0 times; opioids, 13.0 times; hallucinogens, 12.0; stimulants, 11.0; and marijuana and related drugs, 6.0. Surveys of both clinical and nonclinical populations indicate that at least 90 percent of alcoholics are nicotine dependent (32).

Comorbidity affects the course of illness and the response to treatment of both alcoholism and its comorbid illnesses, whether these occur simultaneously or sequentially. Because alcohol-related comorbidity is so common, research is needed to improve the recognition and appropriate management of alcohol abuse and alcoholism occurring in the context of other disorders (18)

Alcoholism and Co-occurring Disorders--A Commentary by
NIAAA Director Enoch Gordis, M.D.

Treatment for co-occurring illnesses in persons with alcoholism should be a standard part of every alcoholism treatment program. Unfortunately, many patients with such illnesses fall through the cracks; for example, alcoholic patients with psychiatric problems who may be rejected by both alcoholism programs and mental health programs. This situation is unacceptable. In many instances, leadership can help solve this problem. Program directors who are concerned about providing the best care to their patients should work within their ser vice areas to develop comprehensive treatment networks for multiply affected patients. In some cases, this may mean facilitating changes in city, county, or State laws to mandate care for such patients. In other cases, it might mean working to resolve differences in treatment philosophy that make it difficult for patients to be treated for comorbid conditions; for example, the requirement of some alcoholism programs that methadone-maintained individuals be drug free before acceptance for treatment. Patients who are alcoholic and who also suffer from other illnesses deserve the same kind of comprehensive care as a cancer patient with pneumonia, or a diabetic patient with glaucoma.

Researchers interested in the causes of disease will differ on whether studying the patient with co-occurring disease is a promising research strategy. On the one hand, the presence of one illness has been known to modify the course of another for better or worse. Clearly, it would be valuable to understand why. On the other hand, because we barely understand the fundamentals of alcoholism, studying it in the presence of other diseases may introduce complications. For example, diabetes increases an individual's risk for atherosclerosis, but researchers interested in atherosclerosis might not choose to unravel the causes of this disease by studying it primarily in diabetic patients.

Because of the increase in the frequency of polydrug abuse, alcoholism treatment programs must be aware of and prepared to deal with this problem in their patients. It should be noted, however, that the most common pattern of abuse in the United States is still alcoholism alone (33).

References

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