Cannabis Use Shrinks The Brain? Not So Fast…

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Cannabis Use Shrinks The Brain? Not So Fast…

You heard the recent news that cannabis use shrinks the brain? Fear not - things are not as bad as the media would have you believe.

Looks like anti-cannabis media outlets are having a field day again! A new study suggests that chronic cannabis use can shrink the grey matter of the brain, whilst simultaneously increasing connections – allowing media outlets to pick and draw misguided conclusions.

You can’t blame them, really. There has been so much positive news surrounding cannabis lately, those who want to see it remain illegal will jump on any chance they get to tarnish the name of weed, no matter how preposterous.

The Study

Carried out by the Davis Centre for Neuroscience at the University of California, this research used MRI technology to compare the brain images of regular cannabis users (who smoke three times a day) against those who have never used it in their lives. It was found that the orbital frontal cortex of the brain, an area associated with decision making, appeared to have less grey matter in smokers, but also created many more connections to other areas of the brain. You can view the research for yourself here.

Take The Results With A Pinch Of Salt

Although interesting, the results do not actually tell us much. As the research is not a longitudinal study, and simply takes a quick ‘snapshot’ into the differences between the groups, it is not possible to see what effects these changes have had in the long-term, for better or worse. It is also impossible to draw conclusions, or establish whether these changes could be caused by other factors within the cannabis users’ lives.

The fact is, until more decisive conclusions can be drawn, this research holds very little real world application to daily life. It may be the case that the difference in the day to day cognitive performance and quality of life between these two groups is indistinguishable – something the author acknowledges stating “chronic users appear to be doing fine”. It could very well be the case that this increased connectivity could actually be a benefit.

What about IQ?

Another point the researchers have observed is that the cannabis using group appear to have a lower average IQ than the non-user group. Once again, this must be taken with a healthy degree of skepticism. A highly regarded review from 2012 found that once other factors were taken into account, such as economic variables, (something this current research does not do), the impact of cannabis on intelligence was likely to be ‘zero’. This is backed up by a longitudinal study from Canada, which followed a group of cannabis users and non-users from birth. They found that cannabis use appeared to have “no long-term negative impact on global intelligence”. 

It Is Not Just Cannabis

The brain is an extremely complicated organ, and concluding that cannabis shrinks the brain does very little but encourage sensationalist headlines. In fact, it is not just cannabis that science has found to impact the hardwiring of the brain. Smoking tobacco also appears to impact the amount of grey and white matter present within MULTIPLE areas of the brain, yet tobacco is a common and completely legal drug. Could it be that the toxins found in all smoke contribute to this effects? Perhaps eating cannabis or vaporizing shows a different effect on the grey matter?

That’s not all though, things like exercise, age, sleep, meditation, and even splitting your attention between your phone and another tasks can all impact the density of grey matter within the brain – sometimes increasing it, sometimes decreasing it. The brain is so complex, that you could almost assume that nearly everything we do shapes and moulds the brain into what it is – adapting it to our way of life. To simply assume that because cannabis appears to effect the brain, and that it must be bad without any empirical evidence to show the real world effects, is an extremely misguided practice – doing an injustice to the reputation of media outlets who value sensationalist headlines over their ability to report credible and balanced news.