Additionally, there is some evidence that would suggest that exposure to drugs could have more of an impact on younger users. A previous study conducted by the Mayo Clinic in 2000 showed that children who have smoked only a few cigarettes experience the same symptoms of nicotine addiction as adults who smoke heavily -- suggesting that early exposure could have a significant impact on health later on in life.
Farb also notes that in studies of other psychologically active drugs -- such as those used to control anxiety -- the response of younger patients differs from that of adults.
While he said that this doesn't necessarily mean that the brains of children are more adversely affected than those of adults when it comes to marijuana, this possibility -- when combined with their prior living situation -- could create a recipe for addiction.
"These things can get coupled, so there are a combination of risk factors present," he said. "You have, if you will, the perfect storm of reinforcement in a child.
"It's bad enough for a child to be in an environment where the behavior is condoned," Farb said. "Add to that the exposure to the drug itself, and it is even worse."