Interesting study.
They are playing it up, but the headlines are lying. They are saying, Pot Users Have Smaller Brains. That is true in a sense, and the earlier the onset of use, the smaller this part of the brain, but that is not the end of the story. The part of the brain is the orbitofrontal cortex. No one knows what this part of the brain does, and it may not do a whole lot. It is very much involved in states of addiction. So maybe this is the alcoholic/pack a day smoker/heroin addict/crackhead part of your brain that mostly just sits there until you take up a habit and then it activates and does whatever, God knows what.
The pot smokers smoked pot on average of three times a day and had started using it from ages 13-30. The younger they started using, the smaller the orbitofrontal cortex was. Pot users had IQ’s on average 5 points lower than controls. That may seem alarming, but for some like me, that leaves me with an IQ of 142, hardly a stupid burnout fried pothead. That should still be enough to kick ass and take names. Towards the lower end up the IQ spectrum, the loss of 5 points may be more significant. Going from 90 to 85 is a much bigger deal than going from 147 to 142, which is barely even meaningful.
Nevertheless, there was no relationship between the size of the orbitofrontal cortex and IQ, so the loss of gray matter in that part of the brain, whatever it was doing, was not making the users more stupid.
In addition, the reduction in size of the orbitofrontal cortex was correlated with increases in connectivity and structure. The younger the person was when they started using, the greater the increases in connectivity and structure were. So the brain was attempting to compensate for the loss of matter in the orbitofrontal cortex by building new highways and storehouses, so to speak. It is known that the brain is plastic in this way, but past a certain point, a person has sustained too much brain damage and plasticity can no longer compensate for it and then you start getting symptoms from brain damage.
Brain damage is also much overdrawn. There are plenty of scary headlines about it, sure, but how many people do you know who have four or more drinks a day. They are all shrinking their brains. Short term heavy drinking of the type often seen in college can depress the brain for up to two years afterwards. So where are all the headlines about this?
Furthermore, it is little known, but we all get brain damage. From age 23 on, our brains are getting more damaged and losing more brain cells. So all the scary headlines say X Drug Kills Brain Cells” which is really dumb because the truth is headlines should read Life Kills Brain Cells. So we should all kill ourselves to avoid brain damage?
In addition, the additional connectivity and structure is a nice addition to your brain, though it is not known what advantages it may have. But pot users will have this increased connectivity and structure that nonusers may not have and there may be advantages to that.
The increases in connectivity and structure slow down after seven years of regular use, but they do not abate. And the more pot you use, the more increases in connectivity and structure you get. And even after quite a few years of heavy use, pot users still had greater brain connectivity than nonusers.
What would be interesting would be to see if the IQ decline corrects itself after a person stops using.