Researchers at the Washington University School of Medicine in St. Louis previously found that exposure to large amounts of alcohol or anesthetic drugs would cause neuroapoptosis (brain cell suicide) in developing brain cells. The their recent experiments, they detected nerve cell death in mice who were given the equivalent of two cocktails over a period of one hour.
"Our animal studies indicate that significant nerve cell death occurs in the infant mouse brain following exposure to blood alcohol levels equivalent to those a human fetus would be exposed to by maternal ingestion of two cocktails," said investigator John W. Olney, M.D., the John P. Feighner Professor of Neuropsychopharmacology, in a news release. "With anesthetic drugs, a dose required to lightly anesthetize an infant mouse for about one hour is sufficient to trigger nerve cell death."
Nerve Cells Die"Assessing the significance of these findings is complicated by the fact that brain cell suicide occurs naturally at a low rate during development," Olney says. "Transient exposure to small amounts of alcohol or an anesthetic drug causes a two- to four-fold increase in the rate of brain cell suicide. Although more nerve cells die than would have died naturally during that developmental interval, we cannot be certain that those cells would not have died at some later time."
Olney's previous research demonstrated that large doses of alcohol can trigger such extensive death of nerve cells that it causes a permanent reduction in the size of the brain and long-term cognitive impairment in mice. He believes the same type of process can explain the harmful effects of alcohol on the developing human brain, a condition known as fetal alcohol syndrome.
"It's the best explanation that has been developed so far for the well-known, devastating effects of alcohol on the human fetal brain," Olney says.
Above the Toxic LevelOlney said it is unlikely that a single glass of wine would cause substantial fetal brain damage, even if expectant mothers consumed such small amounts of alcohol regularly.
"A single glass is not a problem, but if one glass leads to another and then another on the same day, that is a different matter," Olney says. "Because then blood alcohol levels remain above the toxic threshold for too long, and nerve cells commit mass suicide."
Olney said the most prudent advice is to completely avoid alcoholic drinks during pregnancy.
Source: Olney's findings were reported at the 2004 annual meeting of the American Association for the Advancement of Science (AAAS).