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Marijuana alters key brain structures in casual users

The health effects of smoking marijuanaCan casual marijuana use have lasting effects on the brain? A recent study suggests that even light, recreational pot smoking can lead to significant changes in the regions of the brain related to emotion, motivation and reward.

When compared to non-users, young adults who reported smoking marijuana once a week exhibited differences in the size, shape and structure of these brain regions.

For the study, researchers at Massachusetts General Hospital and Northwestern University recruited 40 college students in the Boston area aged 18 to 25. Half of the participants reported using marijuana on a weekly basis. The other 20 were non-users. According to researchers, the pot-smoking participants identified themselves as recreational users who were not dependent on the drug. To confirm this, these subjects underwent psychiatric interviews to ensure that their marijuana use was not impacting their personal lives or academic performance. These participants also reported that they did not have to up their drug use in order to achieve the desired effects.

That said, those who smoked pot exhibited noticeable abnormalities in the volume, shape and density of key brain structures. These irregularities were more extreme in participants who used marijuana more frequently. According to the study, the affected brain regions have been broadly linked to addiction.

Researchers say these brain abnormalities suggest that the drug interferes with brain organization, function and behavior.

“It also is possible that the brain is adapting to marijuana exposure and that these new connections may encourage further marijuana use,” Dr. Anne Blood, a co-senior author from the Massachusetts General Hospital Department of Psychiatry, said in a statement.

Similar findings have come out of previous studies focusing on heavy, long-term marijuana users. This new study is one of the first to look at the drug’s effects among people who only smoke casually. Researchers say the findings raise concerns about the long-term impact of legalizing marijuana.

By Marianne Hayes