Specifically, a new study of substance-using teenagers' brains shows that the regular use of alcohol had a harmful effect on the boozing group, while the toking-up group's brains suffered little alteration.
From Medical Daily, emphasis ours:
The researchers, from the University of California, San Diego and the University of Pittsburgh Medical Center, performed the study on 92 16- to 20-year-olds. The scientists scanned their brains both before and after an 18-month period. Over the course of the 18 months, half of the teens, who already had an extensive track record with alcohol and marijuana, continued their vices as they had before. The other half continued to abstain or drink a minimal amount, like they too had done before the study.While other studies have had less clear results, this study is important for a few reasons.
In addition to the brain scans, the study also required a detailed toxicology report and substance use assessment. The teens also were interviewed every six months. Researchers did not check the teens' cognitive ability, but simply took brain scans.
The researchers found that, after the year and a half was over, kids who had drank five or more alcoholic beverages twice a week had lost white brain matter. That means that they could have impaired memory, attention, and decision-making into adulthood. The teens that smoked marijuana on a regular basis had no such reduction.
First, it shows that early alcohol abuse can be dangerous because it damages the tissues that influence judgement and self-control. "If teens decrease their tissue health and cognitive ability to inhibit themselves, they might become more likely to engage in risky behavior like excessive substance use," the Huffington Post quotes study co-author Joanna Jacobus, postdoctoral fellow at the University of California, San Diego, as saying.
The study authors also said that marijuana strains vary widely, so it's harder to determine which if any ingredients in a typical joint have positive or negative effects. The study will be published in the journal Alcoholism: Clinical and Experimental Research.