Cannabis and adolescent brains: A dangerous cocktail

[David Baxter PhD]

Cannabis and adolescent brains: A dangerous cocktail
Rebecca Burns - McGill University Health Centre
Friday, 18 December 2009

Canadian teenagers are among the largest consumers of cannabis worldwide. The damaging effects of this illicit drug on young brains are worse than originally thought, according to new research by Dr Gabriella Gobbi, a psychiatric researcher from the Research Institute of the McGill University Health Centre. The new study, published in Neurobiology of Disease, suggests that daily consumption of cannabis in teens can cause depression and anxiety, and have an irreversible long-term effect on the brain.

"We wanted to know what happens in the brains of teenagers when they use cannabis and whether they are more susceptible to its neurological effects than adults," explained Dr Gobbi, who is also a professor at McGill University. Her study points to an apparent action of cannabis on two important compounds in the brain - serotonin and norepinephrine (noradrenaline) - which are involved in the regulation of neurological functions such as mood control and anxiety.

"Teenagers who are exposed to cannabis have decreased serotonin transmission, which leads to mood disorders, as well as increased norepinephrine transmission, which leads to greater long-term susceptibility to stress," Dr Gobbi stated.

Previous epidemiological studies have shown how cannabis consumption can affect behavior in some teenagers. "Our study is one of the first to focus on the neurobiological mechanisms at the root of this influence of cannabis on depression and anxiety in adolescents," confirmed Dr Gobbi. It is also the first study to demonstrate that cannabis consumption causes more serious damage during adolescence than adulthood.

Source: Bambico FR, Nguyen NT, Katz N, Gobbi G. Chronic Exposure to Cannabinoids during Adolescence but not during Adulthood Impairs Emotional Behaviour and Monoaminergic Neurotransmission. Neurobiol Dis. 2009 Dec

 

[Neurofreak]

This PR blurb is amazingly disingenuous. The study was done on adolescent rats, not humans, and did not even involve marijuana, but instead a synthetic marijuana analogue that has both a higher for CB1 receptors than marijuana does, and also happens to be structurally quite different.

This isn't to say that theres anything wrong with rat studies, or that inferences can't be made from chemical analogues but to say that "y causes x" is an oversimplification that comes pretty close to just being deceitful.

I go into a little more elaborate detail about this study at my blog. If you'd like to see it do a search for "neurointerests marijuana" (since I can't post a link due to my low post count).

All that being said, it's my personal opinion, of course, that teenagers SHOULD avoid mind-altering substances. My beef is with the presentation -- not the jist of the message. I demand integrity of our media, and when it's not there, I'm going to shout.

Admin note: You can find the referenced blog post at An unsurprisingly disingenuous look at ?marijuana?

 

[Jazzey]

You have an interesting perspective Neuro. My experiences with cannabis are more personal. And, from what I've seen in my life, I would strongly discourage any teenager from engaging down that path...

I have siblings. One of whom has been using cannabis since the age of 13, the other 15. The ramifications have been devastating on their lives.

In the course of my career, I've also had cause to study the ramifications of the use of cannabis. The problem being that in today's society cannabis isn't what it was even 20 years ago - the impurities are always present. So, when you think you're just smokin' the joint - you really aren't.

And again, I've become a fairly adamant proponent against cannabis use because of the ramifications I've seen in my personal life - both with family and friends. I don't need rats to tell me that the regular use of cannabis is not a good plan.

 

[Neurofreak]

And again, I've become a fairly adamant proponent against cannabis use because of the ramifications I've seen in my personal life - both with family and friends. I don't need rats to tell me that the regular use of cannabis is not a good plan.

Fair enough, but that is still anecdotal evidence. People expect that things presented as science are held to a higher standard (control groups, etc.). I really got the impression after reading the blurb that the person who wrote it (not referring to David, mind you) did not even read the actual science paper itself, and yet presumed to put together a piece talking about it. Or worse yet -- put it together with political motivations in mind, what with all of the talk of goings-ons in California.

Even as far as the rats were concerned their tests for anxiety had very, very mixed results.

The truth is, none of this would be a problem if all journals were open access -- allowing people to see the actual science, the data, the figures that go into producing these watered-down news pieces.

 

[David Baxter PhD]

This PR blurb is amazingly disingenuous. The study was done on adolescent rats, not humans, and did not even involve marijuana, but instead a synthetic marijuana analogue that has both a higher for CB1 receptors than marijuana does, and also happens to be structurally quite different.

...

My beef is with the presentation -- not the jist of the message. I demand integrity of our media, and when it's not there, I'm going to shout.

I don't disagree. Media reports of research findings do tend to be woefully inadequate, sensational, and often misleading.

That said, it's the reported irreversibility of the neurochemical changes that makes this worth some attention, even if only in a preliminary way. The mounting evidence, reported poorly or not, is that cannabis is far from the "natural safe high" it was assumed to be in the 60s and 70s.

 

[Jazzey]

Fair enough, but that is still anecdotal evidence. People expect that things presented as science are held to a higher standard (control groups, etc.). I really got the impression after reading the blurb that the person who wrote it (not referring to David, mind you) did not even read the actual science paper itself, and yet presumed to put together a piece talking about it. Or worse yet -- put it together with political motivations in mind, what with all of the talk of goings-ons in California.

I'm not sure what precisely gave you that impression Neuro. Being of a 'scientific' mind, I appreciate the evidence that comes from scientific research.

My anecdote about my personal life - you're right - just anecdotal. But, for me personally, it's enough. I've seen too much in this life to believe that the use of cannabis is 'ok'. Mostly because I believe that it's now become a tool to self-medicate, to compensate for other problems in one's life.

Even as far as the rats were concerned their tests for anxiety had very, very mixed results.

The truth is, none of this would be a problem if all journals were open access -- allowing people to see the actual science, the data, the figures that go into producing these watered-down news pieces.

I don't disagree with you re: having access to the journals. But the reality is that the majority of us (me included) are not in a position to really understand the findings. Is this politically motivated - No. I don't believe so. I think that, for me at least, I'm grateful for the new research coming out on a variety of things.

And, for the record, I was a researchist on medical conditions for a long time. There are sound bases for the researches that are being conducted. And not all of them are politically motivated.

The use of cannabis - it's a hot topic, i'll admit - even in Canada. But it doesn't change the results from the research.

 

[Neurofreak]

Is this politically motivated - No. I don't believe so. I think that, for me at least, I'm grateful for the new research coming out on a variety of things.

Just want to clarify: I don't think the research itself was "politically motivated" so much as the over-generalized translation of the research by the media. I like to keep an open mind, and I think the study itself may even be revealing in some regards, and thus valuable. All aforementioned caveats aside, I have to agree with David that the fact that they detected any altered behavior whatsoever after a 20 day washout (no drug) says something. (Though, what exactly, I'd say it is too early to tell.)

By the way, David, the way this forum shows my recent blog post under each of my posts is really neat.

All the best!

 

[David Baxter PhD]

By the way, David, the way this forum shows my recent blog post under each of my posts is really neat.

Thanks.

With a major software upgrade coming soon, I hope that particular modification survives the transition to the new version.