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article imageCasual marijuana use not free of risk, concludes new research Special

By Ernest Dempsey     Jun 20, 2014 in Health
Boston - Researchers have found that even moderate use of marijuana can harm some brain areas with the risk especially higher in younger users.
Today the mainstream media is bursting with news about marijuana, and particularly the issue of its legalization in US. With many media outlets publishing new studies on the harmless nature of marijuana, as well as its benefits, there is also evidence that casual us of marijuana is also not free of risk. A recent research led by Jodi Gilman of Massachusetts General Center for Addiction Medicine found that two brain areas are affected by weed, even when it is used in moderation. Gilman tells more about her research in the following interview.
Ernest: Jodi, your research comes at a time when we see a lot of media about the pros of marijuana. I’m interested in learning what kind of previous work you built your research on?
JG: My background is in the neuroscience of addiction; specifically, on how drugs of abuse affect the brain. I originally studied how alcohol modulated brain circuits; since marijuana is the most widely used drug among young people, other than alcohol, I was also interested in how marijuana affected the brain. When I looked into the current research on marijuana, I was surprised at how many unanswered questions there were. We know a lot about alcohol (i.e. there are entire scientific journals on alcohol and alcoholism), but much less about marijuana, and this made me want to study its affects.
Ernest: What was the methodology followed in the research and how long it took to complete?
JG: We recruited 40 young adults from the Boston area; half of them used marijuana recreationally, and half of them did not use marijuana. We brought them all into the hospital for neuropsychological testing, a detailed drug use history assessment, and an MRI scan. Then, we analyzed the structures of the brain, comparing the group of marijuana smokers to the group of non-smoking controls. The study took about a year and a half to complete.
Ernest: And what were your findings?
JG: We found that certain brain structures were different between the two groups in their size, shape, and density, and found that the differences correlated with the amount of marijuana that people used. We don’t completely understand how these structural differences relate to health effects; future studies are investigating these questions. We do know that long-term marijuana users have problems with certain brain functions, such as attention and working memory, so future studies are looking at how structural differences in the brain relate to functional outcomes and health risks.
Ernest: I would also like to know how accurate or valid are the results of your study?
JG: The results of this study are very robust and convincing. Like all neuroscience studies, especially with human participants (who all differ in genetics, personality variables, etc.), this study should be replicated with larger sample sizes in order to be sure that the effects we are seeing are robust in other samples.
Ernest: So by your research, moderate or casual use of marijuana is also not free of risk of damage to brain, right? Does it imply a temporary change in brain chemistry or some kind of long-lasting damage?
JG: This is an excellent question, and one that is being actively studied! We cannot say from this particular study if the differences we are seeing are temporary or permanent; in order to know this, we would have to scan marijuana users over time, specifically during the time they are smoking, and then are different time points after they abstain from smoking. It is certainly possible that changes can be reversed if people stop using marijuana, but we don’t know for sure because these studies have not been done. I can say confidently that nothing that we put in our bodies – whether it is alcohol, caffeine, or marijuana – is completely free of any risk. Marijuana is a psychoactive substance; it is naive to think that it would not affect the brain in some way.
Ernest: Medical marijuana is known, or claimed, to be a very effective analgesic and even cure for some major diseases, like some forms of cancer. Do you think it’s safe to be used as analgesic regularly, like daily, in doses prescribed by a doctor?
JG: Again, this is an excellent question, and one that is being studied. All medications have side effects. However, FDA-approved drugs have been carefully dosed and are required to report all side effects publically, and this has not been done for medical marijuana. Marijuana may very well have therapeutic effects, but, just like any other drug, is probably not “completely safe” for everyone. It will be very important for the medical community to weigh the costs and benefits of recommending medical marijuana to patients, especially if they have a family history of psychosis or addiction.
Ernest: The negative effects of marijuana seem to be mostly, or entirely, psychological. Or do you know about any harmful physical effects that regular marijuana use may cause?
JG: People report physical as well as psychological effects; these effects include sleep disruption, headaches, appetite changes and either weight loss or weight gain, and mood swings. These effects can be worse in people who use more marijuana for longer periods of time.
Ernest: Could you tell a little about marijuana’s addictive nature?
JG: Anyone can get addicted to marijuana; there is strong evidence that the earlier people start using marijuana, the more likely they are to become addicted. About 9 percent of users become addicted to marijuana; and when people start smoking as adolescents, this number can increase to about 17 percent. Daily users have a much greater chance of becoming addicted.
Ernest: We are seeing a significant amount of support calling for legalization of recreational marijuana. How do you personally feel about it?
JG: Decriminalization is a good idea because it will reduce the number of incarcerations for marijuana. Decriminalization is not the same as legalization. Legalization will likely lead to more widespread use, especially among young people, and this may lead to more people developing problems with addiction. As scientists, however, it is not our job to make policy; it is our job to educate people about the effects of this drug on the body and the brain. People will ultimately make their own decisions about whether it is worth the risk.
Ernest: Do you believe mainstream media is depicting a complete, objective picture of marijuana and public health?
JG: Generally, I think the mainstream media does a good job of reporting on marijuana, but people should definitely be aware of the sources of information. I have found that when you go outside of mainstream media to various websites and blogs, both pro-legalization groups and anti-legalization groups can exaggerate their claims of both the benefits and the harms of marijuana.
Ernest: Jodi, thanks a bunch for participating in this Q&A about this very important topic.
More about Marijuana Research, marijuana and brain, weed and health, health risks of marijuana
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