Marijuana and the Young Brain

Jodi Gilman, PhD, is the director of neuroscience at the Center for Addiction Medicine. Her research examines how marijuana affects the teen brain. Her team's research has shown that the level of memory decline from marijuana is dependent on the age at which a young person begins using. She notes that this is a matter of public health concern as marijuana use has been shown to affect learning and has been strongly linked to the development of psychotic disorder.

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Transcript

As legalization progresses throughout the United States, this has become a very important issue to study. And believe it or not, there's not a whole lot of research on the effects of cannabis on the brain. It simply wasn't a priority until recently. So, what we're doing is batteries of cognitive testing and MRI scans and functional MRI scans to try to understand the cognitive impact of marijuana use as well as its effects on the function and the structure of the brain.

One of the most well-replicated findings in the cannabis literature are the effects of cannabis on memory. So if you are a frequent cannabis user and you've smoked for a long time, you'll have memory problems.

What we found in our lab is that this is dependent on the age at which you start using marijuana. So, we tested a group of people. They were all young adults between 18 and 25 years old, and we did memory testing. And we found that the students who started using marijuana later, so 17, 18 years old plus, didn't really show the decline in memory performance. But the students who started using at age 14 or 15 showed a remarkable decline in memory.

So we don't know if these memory decrements are preexisting [to] cannabis use, if they were there before they started using cannabis, and that's why they gravitated towards cannabis in the first place because they had underlying vulnerabilities. But something that we have found, and that's been robustly replicated in the literature, is that the earlier you start using cannabis, the worse your outcomes will be.

We're also doing studies in local high schools. So we go into high schools and we test kids. And we're looking at frequent marijuana users and how they learn. And what we find is that if they stop using cannabis, which is part of the paradigm of the study, they learn better immediately within a week of stopping. And that's been really surprising to us, and I think it conveys an important public health message as well.

There's a really strong link between cannabis use and psychosis, schizophrenia and other psychotic disorders. So we're very concerned about the comorbidity of cannabis use and these other psychiatric diagnoses.

So I bring my background in psychology to these studies to try to understand the intersection of cannabis use and disorders such as anxiety and depression. People might think that cannabis helps with their depression, but what we see is that people have worse symptoms when they use cannabis. And that's something that hasn't been studied very well, and we're one of the first groups to study it empirically.

It's our hope that the research that we're doing at the Center for Addiction Medicine could someday be translated into the clinical realm so that what we find out about how cannabis affects the brain, how alcohol affects the brain, could someday be useful to clinicians treating these disorders.

Learn more about the Center for Addiction Medicine

Learn more about addiction treatment for young people