A teen who consumes alcohol is likely to have reduced brain tissue health, but a teen who uses marijuana is not, according to a new study.
Researchers scanned the brains of 92 adolescents, ages 16 to 20, before and after an 18-month period. During that year and a half, half of the teens — who already had extensive alcohol and herb-use histories — continued to use mary-jane and alcohol in varying amounts. The other half abstained or kept consumption minimal, as they had throughout adolescence.
The before-and-after brain scans of the teens consuming typically five or more drinks at least twice a week showed reduced white matter brain tissue health, study co-author Susan Tapert, neuroscientist at University of California, San Diego, told HuffPost. This may mean declines in memory, attention, and decision-making into later adolescence and adulthood, she said.
However, the level of herb use — up to nine times a week during the 18 months — was not linked to a change in brain tissue health. The researchers did not test performance; they only looked at brain scans.
The study was conducted by researchers at UC San Diego and is scheduled to be published in the April issue of the journal Alcoholism: Clinical & Experimental Research.
The damage occurs because white matter brain tissue develops throughout adolescence and into a person’s 20s, Joanna Jacobus, postdoctoral fellow at the UC San Diego, and co-author of the study, told HuffPost.
Part of that still-developing brain tissue is where decision-making ability comes from, which can exacerbate substance use. “It becomes a cycle. 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,” Jacobus said.
The researchers are not sure why alcohol had an effect and marijuana did not. They said the study results cannot be considered definitive without more research. They also said they do not know if the reduced brain tissue health is permanent.
Because the researchers followed the subjects for 18 months, they were able to at least partially monitor preexisting differences in the two groups. But Jacobus conceded that eliminating other factors — such as genetics, home environment, and even minimal use of other drugs — is very difficult.
Each teen in the study received brain imaging, a detailed substance-use assessment, and toxicology screening at the beginning of the study and at the end of the study — as well as substance-use interviews every six months.
Culled from Huffington Post