Adolescent Girls who Use Marijuana at Greater Risk for Brain Impairment

Research that was presented at the 2008 conference of the American Academy of Pediatrics sheds new light on the effect of marijuana on the brains of teens who use the drug, and indicates that girls who smoke pot may be at greater risk for brain damage.

The new information about the relationship between marijuana and the teen brain was uncovered by Krista Lisdahl Medina, an assistant professor of psychology at the University of Cincinnati, and Susan Tapert, an associate professor of psychiatry at the University of California, San Diego. According to an Oct. 14 article on the PhysOrg website, chronic use of marijuana during adolescence has been associated with impairments to attention skills, verbal memory, and the ability to plan:

"Not only are their thinking abilities worse, their brain activation to cognitive tasks is abnormal. The tasks are fairly easy, such as remembering the location of objects, and they may be able to complete the tasks, but what we see is that adolescent marijuana users are using more of their parietal and frontal cortices to complete the tasks. Their brain is working harder than it should," Medina says.

She adds that recent findings suggest females may be at increased risk for the neurocognitive consequences of marijuana use during adolescence, as studies found that teenage girls had marginally larger prefrontal cortex (PFC) volumes compared to girls who did not smoke marijuana.

The larger PFC volumes were associated with poorer executive functions of the brain in these teens, such as planning, decision-making or staying focused on a task.

Though partial recovery was observed within three weeks of abstinence from the drug, the PhysOrg article reported that the researchers observed continued impairment to complex attention skills in adolescents who used large amounts of marijuana.

"Medina says adolescence is a critical time of brain development," the article noted, "and that the findings are yet another warning for adolescents who experiment with drug use."