A woman smokes marijuana rolled as a blunt. Photo by CQ Roll Call
In the wake of states voting to legalize marijuana across the country – and even in Washington’s own backyard – a new study funded by the National Institute on Drug Abuse found that heavy pot use may actually harm the brain.
“We have seen a steady increase in the incidence of marijuana use since 2007,” said one of the study’s authors, Francesca Filbey, in a press release. Filbey, director of cognitive neuroscience research in addictive disorders at the Center for BrainHealth, added that “research on its long-term effects remains scarce despite the changes in legislation surrounding marijuana and the continuing conversation surrounding this relevant public health topic.”
Supporters of loosening marijuana laws have long argued that the drug has little long-term effect on cognition and is less harmful and addictive than cigarettes or alcohol. But the NIDA-funded research suggests that using pot can have a negative impact on the brain, depending on duration and age of first use.
The study found that chronic marijuana use, which is defined as at least four times per week over the past six months, is correlated to adverse changes in the areas of the brain linked to reward, decision making and motivation. Researchers noticed the impact was greater in individuals who started using pot at an earlier age, implying that developing brains are more susceptible to marijuana’s negative effects.
On the flip side, the study also found that long-term marijuana use can enhance some brain circuits, although researchers acknowledged that the brain could just be compensating for reduced function in other regions as a result of the drug.
NIDA said additional studies are still needed to determine if heavy marijuana use directly caused these effects, but it remains to be seen whether lawmakers will seize on the research in an effort to block recently passed legislation in DC to legalize pot. Some Republicans have already signaled they would use the annual appropriations process to prevent the District’s marijuana laws from moving forward.