I would like to make a note before I continue to say that I am not trying to start a fight with those who endorse marijuana use or seem that I endorse it myself. I live in Washington, D.C. where marijuana is now legalized, so this topic pertains to me with the new legislation.

While many people appear to smoke marijuana – in the media’s perception especially – none of these addresses the long-term effects that smoking could have on your brain. Dr. Francesca Filbey, conductor of the newest study at UT Dallas on smoking, says, “research on its long-term effects remains scarce despite the changes in legislation surrounding marijuana and the continuing conversation surrounding this relevant public health topic.” She structured her study so 48 adult marijuana users who typically smoked three times a day were matched with 62 nonsmokers that could counter biases towards race, gender, and age. They also made sure that there was a control for alcohol and tobacco use to make sure that wasn’t a third variable. Subjects were then tested for their IQs and had their brains scanned under three different types of MRIs.

First, the brains of the smokers had a smaller orbitofrontal cortex (OFC), which deals with the senses as well as “stimulus-stimulus learning” (http://www.ncbi.nlm.nih.gov/pubmed/15134840).  While the habitual smokers tended to have a lower IQ, those conducting the study acknowledged “the differences do not seem to be related to the brain abnormalities as no direct correlation can be drawn between IQ deficits and OFC volume decrease.” Another interesting find was that the smokers had an increased connectivity in structure and function of the brain, especially at the age they started, and even though it decreased over 6-8 years it was still a higher connectivity than the non-smokers. While the lower IQs proved the structural and functional creativity do not necessarily equal intelligence, this was an unexpected result from the study.

Although the study is observational, until the long-term effects can be better studied on perhaps people of this generation who will continue to smoke it would be unethical to make people smoke to test how their bodies handle it. I think the survey did a very good job of accounting for third variables and differences in the subjects, even if that meant matching multiple non-smokers to one smoker (which would explain the gap between 48 smokers and 62 non-smokers). However, I don’t think this study should determine how people approach marijuana because it is only the beginning of studies. As Dr. Filbey says herself, “”To date, existing studies on the long-term effects of marijuana on brain structures have been largely inconclusive due to limitations in methodologies…While our study does not conclusively address whether any or all of the brain changes are a direct consequence of marijuana use, these effects do suggest that these changes are related to age of onset and duration of use.”