Search Here

Marijuana, which has recently been approved for medicinal purposes in some areas of the United States, has been considered a relatively safe drug to use in moderation. However, according to a new study, researchers reportedly detected brain changes in young adults who smoke marijuana recreationally.

"Some of these people only used marijuana to get high once or twice a week," said co-author Hans Breiter, reported by the Washington Post. "People think a little recreational use shouldn't cause a problem, if someone is doing OK with work or school. Our data directly says this is not the case. This study raises a strong challenge to the idea that casual marijuana use isn't associated with bad consequences."

For this study, the researchers recruited 40 young adults between the ages of 18 and 25. The adults were from the Boston-area, with most of them being students at Boston University. The researchers grouped the participants into two groups. The first group admitted to using marijuana as little as once per week with a median use of six joints per week. The other group had not used the drug at all within the past year. This group of people stated that they smoked marijuana less than five times over their lifetime.

The researchers conducted scans that measured the volume, shape and density of two specific parts of the brain, which were the nucleus accumbens and the amygdala. The nucleus accumbens is tied to decision-making and motivation and the amygdala is related to emotional behavior. The team discovered that the smokers had larger nucleus accumbens in comparison to the nonsmokers. The smokers' amygdala also has structural changes that were not noticeable in the amygdala of the nonsmokers.

The researchers could not determine if the changes were permanent. They also were not able to find out whether or not these changes affected the smokers' cognitive abilities. Other experts that were not a part of this research believe that these findings indicate that marijuana use, even if it is moderate, might have some sort of negative effect on the brain.

"Anything that underscores that there may be structural changes in the brain [from marijuana use] is important," said Dr. Staci Gruber, an associate psychiatry professor at Harvard Medical School and a director of brain imaging at McLean Hospital.

Stuart Gitlow, president of the American Society of Addiction Medicine, added according to the Boston Globe, "We've known that people who use marijuana when they're younger tend to have cognitive abnormalities, but this gives us direct evidence. It's fairly reasonable to draw the conclusion now that marijuana does alter the structure of the brain, as demonstrated in this study...and that structural alteration is responsible, at least to some degree, for the cognitive changes we have seen in other studies."

The study, "Cannabis Use is Quantitatively Associated with Nucleus Accumbens and Amygdala Abnormalities in Young Adult Recreational Users," was published in the Journal of Neuroscience.