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Alcoholism and the Brain: An Overview

Marlene Oscar–Berman, Ph.D., and Ksenija Marinkovic, Ph.D.**

Alcohol is a Drug

Alcoholism can affect the brain and behavior in a variety of ways, and multiple factors can influence these effects. A person’s susceptibility to alcoholism–related brain damage may be associated with his or her age, gender, drinking history, and nutrition, as well as with the vulnerability of specific brain regions. Investigators use a variety of methods to study alcoholism–related brain damage, including examining brains of deceased patients as well as neuroimaging, a technique that enables researchers to test and observe the living brain and to evaluate structural damage in the brain.

The brain, like most body organs, is vulnerable to injury from alcohol consumption. The risk of brain damage and related neurobehavioral deficits varies from person to person. This article reviews the many factors that influence this risk, the techniques used to study the effects of alcoholism1 on the brain and behavior, and the implications of this research for treatment. (1 Alcohol dependence, also known as alcoholism, is characterized by a craving for alcohol, possible physical dependence on alcohol, an inability to control one’s drinking on any given occasion, and an increasing tolerance to alcohol’s effects [American Psychiatric Association (APA) 1994].)

About half of the nearly 20 million alcoholics in the United States seem to be free of cognitive impairments. In the remaining half, however, neuropsychological difficulties can range from mild to severe. For example, up to 2 million alcoholics develop permanent and debilitating conditions that require lifetime custodial care (Rourke and Löberg 1996). Examples of such conditions include alcohol–induced persisting amnesic disorder (also called Wernicke–Korsakoff syndrome) and dementia, which seriously affects many mental functions in addition to memory (e.g., language, reasoning, and problem–solving abilities) (Rourke and Löberg 1996). Most alcoholics with neuropsychological impairments show at least some improvement in brain structure and functioning within a year of abstinence, but some people take much longer (Bates et al. 2002; Gansler et al. 2000; Sullivan et al. 2000). Unfortunately, little is known about the rate and extent to which people recover specific structural and functional processes after they stop drinking. However, research has helped define the various factors that influence a person’s risk for experiencing alcoholism–related brain deficits, as the following sections describe.

RISK FACTORS AND COMORBID CONDITIONS THAT INFLUENCE ALCOHOL–RELATED BRAIN DAMAGE

Alcoholism’s effects on the brain are diverse and are influenced by a wide range of variables (Parsons 1996). These include the amount of alcohol consumed, the age at which the person began drinking, and the duration of drinking; the patient’s age, level of education, gender, genetic background, and family history of alcoholism; and neuropsychiatric risk factors such as alcohol exposure before birth and general health status. Overall physical and mental health is an important factor because comorbid medical, neurological, and psychiatric conditions can interact to aggravate alcoholism’s effects on the brain and behavior. Examples of common comorbid conditions include:

• Medical conditions such as malnutrition and diseases of the liver and the cardiovascular system

• Neurological conditions such as head injury, inflammation of the brain (i.e., encephalopathy), and fetal alcohol syndrome (or fetal alcohol effects)

• Psychiatric conditions such as depression, anxiety, post–traumatic stress disorder, schizophrenia, and the use of other drugs (Petrakis et al. 2002).

These conditions also can contribute to further drinking.

MODELS FOR EXPLAINING ALCOHOL–RELATED BRAIN DAMAGE

Some of the previously mentioned factors that are thought to influence how alcoholism affects the brain and behavior have been developed into specific models or hypotheses to explain the variability in alcoholism–related brain deficits.

**Marlene Oscar–Berman, Ph.D., is a professor in the Departments of Anatomy and Neurobiology, Psychiatry, and Neurology, Boston University School of Medicine, and a research career scientist at the U.S. Department of Veterans Affairs Healthcare System, Jamaica Plain Division, Boston, Massachusetts.

Ksenija Marinkovic, Ph.D., is a research scientist at the Athinoula A. Martinos Center for Biomedical Imaging, instructor in the Radiology Department at Harvard Medical School, and assistant in Neuroscience at the Massachusetts General Hospital, Boston, Massachusetts.