Alcoholism Health Article

Newer genetic engineering techniques

The introduction of newer techniques developed in the 1990s has contributed to a greater understanding of the complexity of the genetic transmission of alcoholism in humans.

KNOCKOUT AND TRANSGENIC EXPERIMENTS Newer genetic engineering techniques that were developed in the 1990s allow researchers to deactivate, or knock out, a gene that is thought to be involved in sensitivity to or desire for alcohol. Alternately, researchers can insert a gene into an animal's genetic material, thus producing transgenic offspring. Several knockout experiments have produced strains of mice with a craving for alcohol that can be traced to specific proteins in the brain. Both knockout and transgenic experiments on mice have confirmed the hypothesis that low sensitivity to the effects of alcohol appears to be related to a high preference for consuming alcohol.

MICROARRAYS Microarrays are glass slides or silicon chips with selected genes—as many as 10,000—arranged on them for scanning by an automated system. Because alcoholism is a polygenic disorder, and because genes often change their levels of activity in response to the effects of alcohol, microarrays allow researchers to track the activity levels of a large number of genes simultaneously. As of 2001, it is thought that changes in gene function may be a factor in the human brain's long-term adaptations to heavy drinking.

Demographics

Health professionals estimate that 70% of the adult population of the world's developed countries drink alcohol, with a slightly higher rate (75%) in the United States. Of those who drink, about 10% will become alcoholics. This group of heavy drinkers spends more time in the doctor's office or the ER than most other adults; it is estimated that 20% of hospital inpatients and 15% of outpatients have alcohol problems. There is a definite gender imbalance in alcoholism, with males predominating by a ratio of 4:1 or 3:1. According to a 2000 report from the Centers for Disease Control, 22.3% of men are binge drinkers, compared to 6.7% of women. On the other hand, evidence accumulating in the 1990s suggests that the gender ratio is dropping among younger drinkers. A 1997 U.S. Department of Health and Human Services (DHHS) survey found that the current use of alcohol among women is highest in the 26 to 34 age group, and that binge and heavy drinking are highest among 18-to 25-year-olds. The smallest sex differences in heavy drinking are for youths aged 12 to 17 (2% of boys and 1% of girls in 1993; 2% of boys and 1.5% of girls younger than 12 in 1999).

Studies of women alcoholics indicate that women are at higher risk than men for serious health problems related to alcoholism. Because women tend to metabolize alcohol more slowly, have a lower percentage of body water and a higher percentage of body fat than men, they develop higher blood alcohol levels than men at a given amount of alcohol per pound of body weight. Thus, even though women typically begin to drink heavily at a later age than men, they often become dependent on alcohol much more rapidly. This relatively speedy progression of alcoholism in women is called telescoping.

At the other end of the age distribution, alcoholism among the elderly appears to be on the increase as well as underdiagnosed. Confusion and other signs of intoxication in an elderly person are often misinterpreted as side effects of the patient's other medications. In addition, many older people turn to alcohol to medicate feelings of depression. It is estimated, as of 1999, that 15% of older women in treatment for depression are alcoholics. The elderly are at higher risk for becoming dependent on alcohol than younger people because their bodies do not absorb alcohol as efficiently; a 90-year-old who drinks the same amount of alcohol as a 20-year-old (of the same sex) will have a blood alcohol level 50% higher.