Marijuana use is becoming more common and more accepted in society. Several states now allow for medicinal and recreational use, and proponents of the drug claim it is safer than alcohol.
But, while attitudes towards pot are changing, the American Academy of Pediatrics is warning parents not to allow their teens to use it.
"Starting to smoke marijuana at age 21 is different than beginning to smoke at age 14," said Deborah Yurgelun-Todd, PhD, director of the Cognitive Neuroimaging Laboratory at the University of Utah. "In the teen years the brain is still developing."
Yurgelun-Todd has done several studies on the impacts of marijuana on the developing teen brain and says the impacts are clear. Magnetic resonance imaging shows a change in structures and connectivity in the brains of teens who use marijuana compared to the brains of teens who did not.
"It changes how the brain works," she said. "Specifically in ways related to attention and motivation. In addition, early exposure to marijuana tends to lead individuals to other types of drugs."
While she has documented the short-term risks of marijuana use on teen brains, Yurgelun-Todd says there is still research to be done on the long-term impacts. It is believed that teen marijuana use could permanently alter some of the brain's connectivity and structures leading to less effective information processing. A study funded by the National Institutes of Health is now enrolling participants to look at these possible long-term effects.
"It's a 10-year longitudinal study," Yurgelun-Todd said. "The idea is that we will be able to look at brain development and behavior in non-using adolescents as well as in those who initiate drug use in adolescence."
There is also concern about the impacts of marijuana as the drug becomes stronger. Teens who look at their parents or grandparents as examples of people who used the drug and turned out OK may not realize that the marijuana they were using is very different from the marijuana available today.
"There has been an enormous change in the content of the marijuana that is on the streets," said Yurgelun-Todd. "What was previously deemed pretty safe may not be what's out there right now."