- Marijuana May Effect Structure of Brain, Study Says
- March 11, 2015 | Author: Stephen J. Burg
- Law Firm: Burg Simpson Eldredge Hersh & Jardine, P.C. - Englewood Office
- Researchers from the University of Texas and University of New Mexico conducted a study that supports the conclusion that frequent use of marijuana can change the brain.
Whether marijuana use has long-term effects for individuals' brains has long been a controversial topic, and studies have come out supporting both sides of the dilemma, The Washington Post reported. Some studies have found marijuana can cause physical changes in the body and other research found the substance has no effect on IQ.
The researchers of this most recent study analyzed the structural effects marijuana use had on smokers' brains. They used three MRI techniques to look at the brains of 48 marijuana smokers and 62 nonusers. The users smoked an average of three joints per day for approximately 10 years. Each participant also took an IQ test.
The researchers found the orbital frontal cortex, an area of the brain involved in addiction, reward and motivation, was smaller in the marijuana users compared to the nonusers, Forbes reported.
"In previous research, we have observed that changes in the orbital frontal cortex are correlated with greater use of marijuana and behavioral difficulties in participants' personal and professional life," said study author Francesca Filbey, associate professor at University of Texas at Dallas. "It may be that the continued use of marijuana despite problems associated with marijuana suggest impairment in this process."
The researchers saw from their analysis that the younger the participants were when they started to smoke marijuana, the greater change there was in their brain.
While the researchers found an association between smaller OFCs and heavy marijuana use, they were unable to tell whether the marijuana caused a reduction in the size of the OFC or whether people with small OFCs were more likely to smoke marijuana.
Association with IQ
The marijuana users had IQs an average of five points lower than non-smokers. However, the researchers were unsure as to why there was the variation because participants' IQs would not be linked to the size of their OFC. The researchers lacked enough information to speculate as to these findings due to the short duration of the study.
The authors found the smokers had less grey matter in their brain and more connectivity throughout the white matter. The researchers believe the greater amount of connectivity between the areas of the brain is the organ's way of compensating for the reduction in the OFC. However, in users who had been smoking for six to eight years, this increased correspondence within the brain declined.