Study: "Cannabis is harmful to the developing brain"

According to a press release from the Murdoch Childrens Research Institute:

Long term, heavy cannabis use is harmful to the developing brain, according to new research conducted at the Murdoch Childrens Research Institute.

The study, which was published in the leading neurology journal, Brain, found individuals who were heavy cannabis users, who had used for a long period of time, had significant changes in their brains - specifically the areas of brain which connected regions involved in memory function.

Importantly, it also found that the age at which regular cannabis use first began was a key factor in determining the severity of any deterioration in the brain.  This study showed the younger you were when you started, the worse the outcome.  Those who started in early adolescence suffered the greatest abnormalities, and experienced greatest cognitive impairment.  

Lead researcher, Doctor Marc Seal, from Murdoch Childrens, said their findings indicate that that there are critical periods of brain development and ages at which the brain is more vulnerable to damage from regular cannabis use. 

"Our results suggest that long-term cannabis use is hazardous to white matter in the developing brain.  This was especially true for those who had started in adolescence, as we know the brain is still developing during this time."

These findings are significant as we continue the debate about marijuana legalization.  Legalization proponents often say that marijuana is not a harmful drug.  As research on youth use shows, this is simply not true.  Legalization proponents also say that selling marijuana through stores would ensure less access among youth.  This, too, is simply not true.  

If we regulate marijuana like alcohol, access to and use of marijuana among teenagers would increase.  The primary ways teenagers access alcohol are through friends, adults who buy it for them, and at home with or without parental permission.  If marijuana were sold like alcohol, kids would get it the same way.  Easier access among adults means easier access among youth.  

Though teenagers currently say that marijuana is as easy to get as alcohol, fewer use marijuana than use alcohol.  The majority of teenagers who do not use marijuana say they don't because it is illegal.  

Marijuana policy needs to take into account youth access, use, and abuse.  So far, all legalization initiatives have fallen short.