A Little Weed may Change the Teenage Brain
Original story from the Society for Neuroscience
Figure 1 (a) Those regions showing significantly greater GMV in 14 year olds reporting one or two instances of cannabis use than in matched controls. Credit: Orr et al., JNeurosci (2019)
Teenagers who report using recreational marijuana just once or twice display increased volume of numerous brain regions, according to a study of 14-year-olds from Ireland, England, France, and Germany. The research, published in JNeurosci, warrants further study of low-level cannabis use among adolescents amid changing societal attitudes toward the drug.
Analyzing data from a large research program investigating adolescent brain development and mental health, Catherine Orr, Hugh Garavan, and colleagues identified brain regions rich in cannabinoid receptors that showed structural differences in teenagers who reported limited cannabis use. These differences persisted despite controlling for many variables, including sex and socioeconomic status as well as alcohol and nicotine use, and were only apparent after cannabis use. Finally, the researchers demonstrate associations between increased grey matter volume in low-level cannabis users and assessments of reasoning and anxiety.
Given the important role of the endogenous cannabinoid system in brain development during adolescence, teenagers may be particularly vulnerable to the effects of THC, the primary psychoactive component of marijuana. Additional research is needed to determine whether these findings apply to more diverse populations beyond the four European countries studied here.
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Catherine Orr, Philip Spechler, Zhipeng Cao, Matthew Albaugh, Bader Chaarani, Scott Mackey, Deepak D'Souza, Nicholas Allgaier, Tobias Banaschewski, Arun L.W. Bokde, Uli Bromberg, Christian Büchel, Erin Burke Quinlan, Patricia Conrod, Sylvane Desrivières, Herta Flor, Vincent Frouin, Penny Gowland, Andreas Heinz, Bernd Ittermann, Jean-Luc Martinot, Marie-Laure Paillère Martinot, Frauke Nees, Dimitri Papadopoulos Orfanos, Tomáš Paus, Luise Poustka, Sabina Millenet, Juliane H. Fröhner, Rajiv Radhakrishnan, Michael N. Smolka, Henrik Walter, Robert Whelan, Gunter Schumann, Alexandra Potter, Hugh Garavan. Grey Matter Volume Differences Associated with Extremely Low Levels of Cannabis Use in Adolescence. The Journal of Neuroscience, 2019; 3375-17 DOI: 10.1523/JNEUROSCI.3375-17.2018