I'm not the poster you're replying to, but this popped up in a quick search:That is interesting, thanks for sharing, do you know from which study/studies this information came from?
Grey Matter Volume Differences Associated With Extremely Low-Level Cannabis Use in Adolescence
The summary sentence of that study:
Given the increasing levels of cannabis use among adolescents today, we suggest that studying the effects of recreational use early in life is an area of particular importance that should be addressed in the future by large scale, prospective studies.
The thing about these sorts of initial investigations is: they serve to support further study. They are generally small-to-mid size, and are simply trying to figure out if there's anything more specific worth pursuing in the area of interest. These studies also don't claim to 'prove' much of anything, except to say "hey, look - something happened. We're not sure what, but we did enough to know that there's more data here."
The misinterpretation of studies - that happens when outlets for more general or broad, laymen's terms articles try and make the data simpler, giving the highlights of the study, without the dense factual context......they inevitably leave readers with the impression that a conclusion has been drawn; when really, the study is only there to support more study.
Which is actually an important aspect to how research works - it's not a flaw, it's the process.
/soapbox on studies
Changes in the brain will consist of both volume and density changes, along with cortical thickness and overall shape. Like you said, @Freddyt - the brain 'shrinking' is normal. What's unexpected is when it happens as a matter of course in growth, not aging - though that is counterbalanced by the brain becoming more dense. It's a lot to factor in.
The one thing that is fairly solid, relating to negative effects of cannabis in adolescents is: if the kid's brain is pre-wired for the types of changes that accompany schizophrenia, cannabis use is likely to seal the deal. Really, any adolescent carrying genetic history of mental illness should be very careful with any substance use until they've passed the age of 24/25....but I don't know how anyone could get a teenager to buy into that possibility of kicking off their life-changing mental illness by getting drunk a few times, or trying weed a couple of times.
I cannot wait for earlier preventative mental health screening that is reliable, objective, and something that can be effectively and safely addressed by modern medicine. Whatever that medicine turns into? Whether it's controlled use of heavier psychogenics or aggressive anti-inflammatories or f*cking little purple daisies, I don't care. Just shit that works for everyone. That will be a good day, in my book.