Smoking Marijuana Once a Week Alters Brain Areas, Study

Young adults, who smoke a joint once a week, undergo changes in brain areas concerned with emotions and motivation, according to a study.

Previous studies have found that Delta-9-tetrahydrocannabinol (THC), the major psychoactive element found in marijuana, impairs memory, perception and learning abilities and causes damages to the heart, lungs and reproductive organs.

A research team from the Northwestern University's Medical School, Massachusetts General Hospital and Harvard University found that youngsters, who occasionally indulge in smoking marijuana, undergo size and structural changes in brain areas that regulate emotional and motivational behavior.

The study involved 20 casual smokers and 20 non-smoking youngsters aged between 18 and 25. Using MRI scans, experts observed brain alterations of participants from both groups for nearly three months.

Researchers found that youngsters, who reported smoking marijuana weekly once, had notable variation in the shape and size of "nucleus accumbens" and "Amygdala- regions" of the brain that are associated with emotional reactions, reward anticipation, decision making, learning, and impulsivity. The scans revealed changes in the shapes of these areas which were larger in marijuana users compared to non-smoking participants.

Carl Lupica, from the National Institute on Drug Abuse who was not involved in the research said in a news release," This study suggests that even light to moderate recreational marijuana use can cause changes in brain anatomy. These observations are particularly interesting because previous studies have focused primarily on the brains of heavy marijuana smokers, and have largely ignored the brains of casual users."  

The study also revealed that higher the drug use, severe deformity is more likely to occur in both regions. The researchers said that further studies will be needed to predict the long-term health risks.

According to the National Institute on Drug Abuse, 42.8 percent of the marijuana smokers constitute school going children aged between 12 and 17, while young adults aged 18 and above comprise 52 percent of the smoking population.

Hans Breiter, study author and researcher from the Harvard Medical School said, "This study raises a strong challenge to the idea that casual marijuana use isn't associated with bad consequences."

More information is available in the online journal of Neuroscience.

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