A study conducted by researchers from the University of Texas’ Center for Brain Health and the Albuquerque-based Mind Research Network has found evidence that chronic pot smokers have less gray matter than people who have never smoked marijuana. Published in the Proceedings of the National Academy of Sciences (PNAS), the observations of decreased gray matter were found in the orbital frontal cortex, an area of the brain that is related to the decision-making and addictive behaviors network. The finding had been widely observed among mice but disputed for human beings.
Yet the researchers also found higher connectivity relating to white matter in the chronic pot smokers, which is associated with better adaptive learning. The authors of the study could not determine whether there is a causal relationship between the pot use and levels of gray matter, and they could only make a correlation between pot use and IQ. The study used 62 non-pot smokers and 48 chronic pot smokers (people who used marijuana at least four times a week over the past six months), matched for age and gender.
Will these findings deter marijuana users? How will the growing science around marijuana shape the national debate?
Sina Aslan, Assistant Adjunct Profressor at the Center for Brain Health at the University of Texas at Dallas, one of the co-authors of the marijuana study
Dr. David Agus, Professor of Medicine and Engineering at the University of Southern California and Director of the Westside Cancer Center