Recreational cannabis use can have damaging effects for young adults, according to a “Journal of Neuroscience” report released Wednesday by researchers from Harvard Medical School, Massachusetts General Hospital and Northwestern University.
The study’s nine researchers, Dr. Jodi Gilman, Dr. John Kuster, Dr. Sang Lee, Myung Joo Lee, Byoung Woo Kim, Dr. Nikos Makris, Dr. Andre van der Kouwe, Dr. Anne Blood and Dr. Hans Breiter conducted tests on animals and adults between the ages of 18 and 25, including several Boston University students. They found cannabis use can cause damage to the brain and impair cognitive ability, according to the report.
“It is … the most widely used illicit drug on college campuses,” the report stated. “Moreover, its use is increasing among adolescents and young adults, partially due to society’s changing beliefs about cannabis use and its legal status.”
Researchers tested recreational users, those who smoke cannabis as little as once a week, for over two years, and compared their MRI scans to those of non-users. A number of users did not report negative effects from using cannabis, but the researchers said there were differences found in brain activity, Blood said.
“These brain structures showed abnormalities in the structural measures or differences between people who used marijuana and those who did not,” she said. “Work is needed to understand the implications of that, but these regions affect motivation and being able to determine what is rewarding.”
The experiment’s results were concerning, Blood said, due to the false perceptions held by people, especially young adults, about the illicit drug.
“What is worrisome is that people are using marijuana without knowing a lot about what it might be doing to their brains,” she said. “We want to raise the issue that the conclusion that marijuana is safe is not based on any medical research. It is just general perception.”
Paul Armentano, deputy director of The National Organization for the Reform of Marijuana Laws, said studies conducted have shown that cannabis use has nominal long-term or adverse effects on cognitive thinking, but he said their organization supports the legalization of cannabis.
“Those of us who advocate for a change in cannabis laws do not argue that the use of cannabis is not without potential risks,” he said. “However, it is apparent that these associated potential risks are not so great as to warrant the continued arrest of some 700,000 Americans annually … nor do they justify its present status as a schedule I controlled substance – a classification that equates the purported dangers of pot to be equal to those of heroin.”
Use of cannabis at a young age can stunt developmental growth and cause mental disorders because the drug is “a big dose of potent chemicals,” said Dr. Sharon Levy, director of the Adolescent Substance Abuse Program at Boston Children’s Hospital.
“This study showed that kids who use marijuana particularly during adolescence have disorders such as schizophrenia, mood disorders and bipolar disorders,” she said. “As a clinician and a behavioral health researcher, and based on my reading of the literature, I am concerned that marijuana may have a damaging impact on the brain because the chemicals are outcompeting the body’s own chemical-messaging systems.”
Several residents said they are not concerned about whether or not adults are smoking cannabis, but do not condone use of the illicit drug by adolescents.
Madeleine Brown, 19, of Back Bay, said she understands why the drug is harmful to the brain, but expects most people to be surprised at the extent of the report’s results.
“Most people say that it’s harmless, and I believe them, but I wouldn’t be surprised if it is actually harmful,” she said. “At the same time, most people would be shocked if they found out it was harmful because doctors prescribe it to sick patients in order to help them get better and feel better.”
Sean Temple, 25, of Brighton, said he was not surprised by the report’s findings.
“When you put some kind of outside chemical into your body, it usually has or can have some sort of effect on you,” he said. “If people are going to try it [marijuana], I don’t really know what you would do to stop them. It’s kind of like how people smoke cigarettes and know they can cause them harm.”
Christine McEvoy, 26, of Dorchester, said she does not support cannabis use and would not condone use of the drug even if recreational use was legal.
“I don’t see any benefits to it,” she said. “This [study] shows that we should be active in making sure young students aren’t using it. I don’t see it being positive for people. I don’t see it adding anything to a person’s life.”