February 11, 2000
Alcohol-Brain Cell Link Found
By The Associated Press
WASHINGTON (AP) -- Laboratory studies suggest that a single drinking binge by a pregnant woman can damage for life the brain of her unborn child.
That's the conclusion of a study published today in the journal Science on the effects of alcohol on the very young.
The conclusion is based on a study conducted on laboratory rats, but experts said the work helps to explain why children born to drinking mothers can suffer learning disabilities, memory loss and other brain disorders.
The study indicates that rats, and presumably humans, are highly susceptible to alcohol-related neurological damage when developing brain cells are furiously building the connections needed for memory, learning and thought. In humans, this period of rapid brain development starts in the sixth month of gestation and continues for two years after birth. In rats, it comes in the two weeks after birth.
``We call this a brain-growth spurt period,'' said Dr. John W. Olney, a Washington University School of Medicine researcher and senior author of the study.
During this spurt, said Olney, a single prolonged contact with alcohol -- lasting for four hours or more -- is enough to kill vast numbers of brain cells.
``There is a massive wave of cell suicide after the brain is exposed to ethanol (alcohol),'' said Olney. ``The cells die by the millions and millions.''
During the brain's growth spurt, called synaptogenesis, brain cells must receive a balanced signal from two types of neurotransmitter chemicals, glutamate and GABA, he said. If this signal is disrupted, the developing brain cells are programmed to commit suicide. This is the body's way of eliminating surplus cells.
But, based on the rat studies, alcohol severely disrupts the glutamate-GABA signals and this, in turn, causes nerve cell suicide at about 15 times the normal rate, he said.
Neuron cells that normally die during brain development are about 1.5 percent of the total, but in rat pups exposed to alcohol just days after birth, said Olney, the dead neurons ranged from 5 to 30 percent of the total.
``Our study showed that it only requires one round of intoxication of about four hours for this to occur,'' said Olney.
The ``binge'' used in the study gave the rats a blood alcohol level of .20, or 200 milligrams of alcohol per deciliter of blood. Such a level in people is twice the legal standard of drunkenness in many states.
Dr. David Lovinger of the Vanderbilt University School of Medicine said in Science that the study carries a powerful message: Drinking in late pregnancy ``is really unsafe for the brain.''
A 1996 study by the Institute of Medicine showed that about 20 percent of women who drink do not stop during pregnancy. About one in every 1,000 babies born in the United States suffers from fetal alcohol syndrome, a disorder caused by exposure to alcohol in the womb. The disorder can cause stunted growth, along with memory and learning problems.
Olney said pregnant women need not be anxious about past, moderate alcohol drinking.
``One glass of wine at dinner is unlikely to cause the damage, but we cannot say that any added intake would be safe,'' he said. ``The most prudent policy would be to have no alcohol during pregnancy.''
[Science News, Vol. 158, No. 2, July 8, 2000, p. 28]
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