A new study conducted at The University of Texas at Dallas found a connection between long-term marijuana use and abnormalities in a key region of the brain. Findings of this study were published on November 10 in the Proceedings of the National Academy of Sciences journal.
Research showed a greater connectivity in this region of the brain in long-term marijuana users compared to people who do not smoke marijuana. Researchers also discovered that this connectivity disappears over time with prolonged use but that the younger an individual is when first starting to use marijuana the more significant the abnormalities.
The one thing the study could not determine is whether the abnormalities in this region of the brain cause any emotional or mental deficits.
Dr. Francesca Filbey, study leader and director of the university’s Center for Brain Health, as well as associate professor in the university’s School of Behavioral and Brain Sciences stated that the orbital frontal cortex is a key component of the brain’s network and reward system. As such, it is instrumental in a person’s decision-making, adaptive learning, and motivation capabilities.
Dr. Filbey added that based on the findings of the study, chronic marijuana users have smaller brain volume in that region. Because of this, there is the potential of manifestation of behavior that makes it difficult to modify learned behavior.
In order to conduct the study, Dr. Filbey along with her colleagues compared the brains of 48 adults who smoked marijuana three times per day over a 10-year period of time using MRI scanners. These findings were then compared to the brains of 62 adults who do not smoke marijuana.
Experts like Dr. Asaf Keller, professor of anatomy and neurobiology at the University of Maryland School of Medicine agrees the study’s findings are provocative but do not prove that marijuana use is directly responsible for changes in the brain.
Dr. Keller said this is a retrospective type study opposed to being a prospective one. For that reason, determining if individual differences in the brain’s anatomy are connected to environmental or genetic factors beyond marijuana use is impossible. The bottom line, there is no indication that anatomical difference in the brains of people who smoke marijuana are caused by this herb.
Although Dr. Keller has long been critical of research that links casual marijuana use to changes in the brain, many respected researchers disagree and feel this study is a huge and important step forward specific to marijuana research.
In a statement from Dr. Susan F. Tapert, psychiatry professor at the University of California, San Diego and who was not involved with this new study, the research conducted was well done and can be used as a reminder that risks might be associated with smoking marijuana. In looking at the findings, there is a need for definitive studies to be done.