FRIDAY, Aug. 21, 2009 (HealthDay News) -- Marijuana may buffer the brain against the damages of binge drinking, a new study suggests.

Researchers from the University of California, San Diego, used high-tech scans to compare microscopic changes in brain white matter in teens aged 16 to 19 who were divided into three groups: binge drinkers (boys who consume five or more drinks at one sitting, and girls who have four or more drinks); binge drinkers who also smoked marijuana; and a control group with little or no experience with either alcohol or drugs.

As expected, the binge drinkers showed signs of white matter damage in all eight brain regions examined by the researchers. But the binge drinkers/marijuana users had less damage in seven out of the eight brain regions than the binge drinkers did. And compared to the control group, the binge drinkers/marijuana users had more white matter damage in only three regions.

The researchers wrote that brain white matter tracts were "more coherent in adolescents who binge drink and use marijuana than in adolescents who report only binge drinking." They said it's "possible that marijuana may have some neuroprotective properties in mitigating alcohol-related oxidative stress or excitotoxic cell death."

The study appears in the current issue of the journal Neurotoxicology and Teratology.

"This study suggests that not only is marijuana safer than alcohol, it may actually protect against some of the damage that booze causes," Steve Fox, director of state campaigns for the Marijuana Policy Project, said in a news release from the project.

"It's far better for teens not to drink or smoke marijuana, but our nation's leaders send a dangerous message by defending laws that encourage the use of alcohol over marijuana," he added.

More information

The U.S. Centers for Disease Control and Prevention has more about binge drinking.