Last Updated: 2003-06-03 13:09:58 -0400 (Reuters Health)

NEW YORK (Reuters Health) - An antioxidant substance appears to thwart the brain-cell-killing effects of alcohol, according to a study in rats.

The findings suggest that the compound, or others like it, could be used in treating mental impairment associated with alcoholism, the researchers said.

While it has long been known that alcohol abuse can impair memory and other mental abilities, it is not yet clear exactly how alcohol harms brain cells.

In the new study, researchers found that rats fed alcohol formed fewer new brain cells, or neurons, and showed greater cell death than those on a normal diet.

"We demonstrated that in a model of alcoholism, neurogenesis (brain-cell formation) was impaired," Dr. Daniel G. Herrera, of Weill Medical College of Cornell University in New York, told Reuters Health.

This impairment, Herrera explained, occurred, at least in part, because newly formed cells were dying.

According to the researcher, substances with antioxidant properties have been shown to prevent the death of liver cells. So Herrera's team hypothesized that antioxidants -- which neutralize cell-damaging forms of oxygen called free radicals -- might similarly protect brain cells from alcohol damage.

To investigate, the researchers fed rats either a regular liquid diet or one that contained ethanol (alcohol). Some of the rats in each group also received a potent synthetic antioxidant called ebselen.

After six weeks, rats fed alcohol showed a 66 percent decrease in the number of new neurons and a two- to three-fold increase in cell death in a portion of the brain, when compared with rats that ate a regular diet.

In rats that got both alcohol and ebselen the scientists saw no similar reduction in brain-cell formation and no increase in cell death.

The findings are published online in the Proceedings of the National Academy of Sciences Early Edition.

Studies in recent years have indicated that alcohol may affect different brain areas in different ways, according to Herrera. In the rat study, neurogenesis was impaired in a brain structure called the dentate gyrus, which is located in the hippocampus, the brain's "memory center."

"Effects on neurogenesis could give an alternative explanation to how alcohol affects certain brain structures and specific cognitive functions more than others," Herrera said.

What's more, he and his colleagues write, their findings suggest that ebselen or similar compounds could be useful in treating mental impairment in alcoholics -- and possibly in other brain disorders where neurogenesis might be affected.

However, Herrera said, more research is needed into the precise role of neurogenesis in brain function and repair.