A study just published online by the journal Neurotoxicology and Teratology suggests that marijuana may protect the brain from some of the damage caused by binge drinking.
The study, by researchers at the University of California San Diego, used a type of high-tech scan called diffusion tensor imaging to compare microscopic changes in brain white matter.
The subjects were students aged 16-to-19, divided into three groups: binge drinkers (defined as having five or more drinks at one sitting for boys or four or more for girls), binge drinkers who also smoked marijuana, and a control group who had very little or no experience with either alcohol or drugs.
As expected, the binge-drinking-only group showed evidence of white matter damage in eight regions examined, as demonstrated by lower fractional anisotropy (FA) scores. But in a finding the researchers describe as "unexpected," the binge-drinking/marijuana group had lower FA scores than the controls in only three of eight regions, and in seven regions the binge-drinking/marijuana group had higher scores — indicating less damage — than the binge drinkers who did not use marijuana.
Brain white matter tracts were "more coherent in adolescents who binge drink and use marijuana than in adolescents who report only binge drinking," the researchers wrote.
"It is possible that marijuana may have some neuroprotective properties in mitigating alcohol-related oxidative stress or excitotoxic cell death," as has already been shown in lab and animal studies.