ALCOHOL’S DAMAGING EFFECTS ON THE BRAIN

Difficulty walking, blurred vision, slurred speech, slowed reaction times, impaired memory: Clearly, alcohol affects the brain. Some of these impairments are detectable after only one or two drinks and quickly resolve when drinking stops. On the other hand, a person who drinks heavily over a long period of time may have brain deficits that persist well after he or she achieves sobriety. Exactly how alcohol affects the brain and the likelihood of reversing the impact of heavy drinking on the brain remain hot topics in alcohol research today.

We do know that heavy drinking may have extensive and far–reaching effects on the brain, ranging from simple “slips” in memory to permanent and debilitating conditions that require lifetime custodial care. And even moderate drinking leads to short–term impairment, as shown by extensive research on the impact of drinking on driving.

A number of factors influence how and to what extent alcohol affects the brain , including

* how much and how often a person drinks;
* the age at which he or she first began drinking, and how long he or she has been drinking;
* the person’s age, level of education, gender, genetic background, and family history of alcoholism;
* whether he or she is at risk as a result of prenatal alcohol exposure; and
* his or her general health status.

This Alcohol Alert reviews some common disorders associated with alcohol–related brain damage and the people at greatest risk for impairment. It looks at traditional as well as emerging therapies for the treatment and prevention of alcohol–related disorders and includes a brief look at the high–tech tools that are helping scientists to better understand the effects of alcohol on the brain.

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BLACKOUTS AND MEMORY LAPSES

Alcohol can produce detectable impairments in memory after only a few drinks and, as the amount of alcohol increases, so does the degree of impairment. Large quantities of alcohol, especially when consumed quickly and on an empty stomach, can produce a blackout, or an interval of time for which the intoxicated person cannot recall key details of events, or even entire events.

Blackouts are much more common among social drinkers than previously assumed and should be viewed as a potential consequence of acute intoxication regardless of age or whether the drinker is clinically dependent on alcohol . White and colleagues surveyed 772 college undergraduates about their experiences with blackouts and asked, “Have you ever awoken after a night of drinking not able to remember things that you did or places that you went?” Of the students who had ever consumed alcohol, 51 percent reported blacking out at some point in their lives, and 40 percent reported experiencing a blackout in the year before the survey. Of those who reported drinking in the 2 weeks before the survey, 9.4 percent said they blacked out during that time. The students reported learning later that they had participated in a wide range of potentially dangerous events they could not remember, including vandalism, unprotected ***, and driving.
Equal numbers of men and women reported experiencing blackouts, despite the fact that the men drank significantly more often and more heavily than the women. This outcome suggests that regardless of the amount of alcohol consumption, females—a group infrequently studied in the literature on blackouts—are at greater risk than males for experiencing blackouts. A woman’s tendency to black out more easily probably results from differences in how men and women metabolize alcohol. Females also may be more susceptible than males to milder forms of alcohol–induced memory impairments, even when men and women consume comparable amounts of alcohol .


Binge Drinking and Blackouts

• Drinkers who experience blackouts typically drink too much and too quickly, which causes their blood alcohol levels to rise very rapidly. College students may be at particular risk for experiencing a blackout, as an alarming number of college students engage in binge drinking. Binge drinking, for a typical adult, is defined as consuming five or more drinks in about 2 hours for men, or four or more drinks for women.

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ARE WOMEN MORE VULNERABLE TO ALCOHOL’S EFFECTS ON THE BRAIN?

Women are more vulnerable than men to many of the medical consequences of alcohol use. For example, alcoholic women develop cirrhosis , alcohol–induced damage of the heart muscle (i.e., cardiomyopathy) , and nerve damage (i.e., peripheral neuropathy) after fewer years of heavy drinking than do alcoholic men. Studies comparing men and women’s sensitivity to alcohol–induced brain damage, however, have not been as conclusive.

Using imaging with computerized tomography, two studies compared brain shrinkage, a common indicator of brain damage, in alcoholic men and women and reported that male and female alcoholics both showed significantly greater brain shrinkage than control subjects. Studies also showed that both men and women have similar learning and memory problems as a result of heavy drinking . The difference is that alcoholic women reported that they had been drinking excessively for only about half as long as the alcoholic men in these studies. This indicates that women’s brains, like their other organs, are more vulnerable to alcohol–induced damage than men’s .

Yet other studies have not shown such definitive findings. In fact, two reports appearing side by side in the American Journal of Psychiatry contradicted each other on the question of gender–related vulnerability to brain shrinkage in alcoholism . Clearly, more research is needed on this topic, especially because alcoholic women have received less research attention than alcoholic men despite good evidence that women may be particularly vulnerable to alcohol’s effects on many key organ systems.
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BRAIN DAMAGE FROM OTHER CAUSES

People who have been drinking large amounts of alcohol for long periods of time run the risk of developing serious and persistent changes in the brain. Damage may be a result of the direct effects of alcohol on the brain or may result indirectly, from a poor general health status or from severe liver disease.

For example, thiamine deficiency is a common occurrence in people with alcoholism and results from poor overall nutrition. Thiamine, also known as vitamin B1, is an essential nutrient required by all tissues, including the brain. Thiamine is found in foods such as meat and poultry; whole grain cereals; nuts; and dried beans, peas, and soybeans. Many foods in the United States commonly are fortified with thiamine, including breads and cereals. As a result, most people consume sufficient amounts of thiamine in their diets. The typical intake for most Americans is 2 mg/day; the Recommended Daily Allowance is 1.2 mg/day for men and 1.1 mg/day for women .