Heavy cannabis use associated with reduced dopamine release in brain, similar to other addictions

[Alchemica]

Heavy cannabis use associated with reduced dopamine release in brain, similar to other addictions

 

In a recent study, researchers found evidence of a compromised dopamine system in heavy users of marijuana. Lower dopamine release was found in the striatum - a region of the brain that is involved in working memory, impulsive behavior, and attention. Previous studies have shown that addiction to other drugs of abuse, such as cocaine and heroin, have similar effects on dopamine release, but such evidence for cannabis was missing until now.

 

"In light of the more widespread acceptance and use of marijuana, especially by young people, we believe it is important to look more closely at the potentially addictive effects of cannabis on key regions of the brain," said Anissa Abi-Dargham, MD, professor of psychiatry (in radiology) at Columbia University Medical Center (CUMC) and a lead author of the paper.

 

The study included 11 adults between the ages of 21 and 40 who were severely dependent on cannabis and 12 matched healthy controls. On average, the cannabis group started using at age 16, became dependent on cannabis by age 20, and have been dependent for the past 7 years. In the month prior to the study, nearly all users in this study smoked marijuana daily.

 

Using positron emission tomography (PET) to track a radiolabelled molecule that binds to dopamine receptors in the brain, the scientists measured dopamine release in the striatum and its subregions, as well as in several brain regions outside the striatum, including the thalamus, midbrain, and globus pallidus. The cannabis users in this study stayed in the hospital for a week of abstinence to ensure that the PET scans were not measuring the acute effects of the drug. Participants were scanned before and after being given oral amphetamine to elicit dopamine release. The percent change in the binding of the radiotracer was taken as an indicator of capacity for dopamine release.

 

Compared with the controls, the cannabis users had significantly lower dopamine release in the striatum, including subregions involved in associative and sensorimotor learning, and in the globus pallidus.

 

The investigators also explored the relationship between dopamine release in a key area of the striatum and cognitive performance on learning and working memory tasks. Although there was no difference between groups in task performance, in all participants lower dopamine release was associated with worse performance on both tasks.

 

"We don't know whether decreased dopamine was a preexisting condition or the result of heavy cannabis use," said Dr. Abi-Dargham. "But the bottom line is that long-term, heavy cannabis use may impair the dopaminergic system, which could have a variety of negative effects on learning and behavior."

 

Jeffrey Lieberman, MD, Chair of Psychiatry at CUMC and past president of the American Psychiatric Association, noted that "these findings add to the growing body of research demonstrating the potentially adverse effects of cannabis, particularly in youth, at the same time that government policies and laws are increasing access and use."

Edited April 16, 2016 by Alchemica

[ThunderIdeal]

reduced dopamine release... aint nobody got time for that!

[HolographicYou]

Interesting article Alchemica, thanks for sharing!

Now we wait for the famous "pot isnt addictive" remarks? Its about time some actual study has been done in this area, I know many people who are dependent on cannabis including myself some time ago. Not that I believe its worse than an alcohol problem but I think its important to clear the mis-information around this plant, even (especially?) if it means debunking a possitive quality that people have been taking for granted.

[-RC-]

Bait taken!

 

That study just confirmed what my Nanna told me when I was 5: "Too much of a good thing is a bad thing..." She didn't even have brain imaging or nuffin back then...

 

For the record the majority of misinformation that is out there is due to concerted propaganda campaigns by government agencies, not old mate who can't go 5 mins without a hot one.

 

I tend to put more stock in more-independent research apart from the American Psychiatric Association. I'm putting on my cynical hat here, but wouldn't they be the mob responsible largely for flooding America with SSRi's? No connection to Big Pharma there? Particularly when many in the US are subbing such toxic and potentially lethal drugs with cannabis?

 

'Loss of market share' I believe the term is, not harm-reduction.

 

My 'official' stance, with big props to the ISCD: http://www.responsiblechoice.com.au/cannabis/cannabis-effects-101/

 

No-one here is saying regular cannabis use can't lead to dependence, but so can regular viewing of porn, or eating Macca's. Both will have an effect on Dopamine levels in the brain. Not many things we consume don't. I guess the point of difference I would like to highlight is that no-one dies from ODing on cannabis if they are dependent, nor do they go around flogging stuff to sell to support the habit. The withdrawals that may lead to that behavior are too minor really.

 

That said I think the more important question that org's like the APA should be asking is "Why are people becoming dependent?" As in what is going on in their lives that is making them seek the succor of Lady Ma so regularly, which may or may not lead to problematic use. Everyone is different and responds to different drugs accordingly.

 

I guess?

[SayN]

^ Good guess, i reckon. I wish I could like, like twice...

[Conv3rgence]

Makes sense.... Small amounts of dopamine are released when we achieve small goals, like a self reward system. Perhaps the unmotivated stoner stereotype is a result of reduced dopamine release - a heavy cannabis user is feeling less fulfilment in daily life from doing things and thereby loses the 'drive' to continue achieving. (Just a thought, could be entirely wrong here!)

[waterboy 2.0]

Am I off me guts or is there no link or actual reference to the "study" on that page or actually name the study title?

 

My dopamine production is not damaged enough to just jump to others conclusions necessarily.

 

(EDIT - lol...this isnt the same crew that used PET scanning to claim shrinkage in part of the brain in a shamefully flawed study group?).

Edited April 16, 2016 by waterboy 2.0

[Strontium Dawg]

My dope-amine production is fine too dubya bee.

[BedOSpines]

haha

[freakazoid]

Too much is bad for you.... No shit. Like 10 coffees a day and it starts making you tired, like 2 litres of wine a day, after a while just puts you to sleep with your 12th glass, like 18 hrs sleep a day increases your risk of cancer, like loads of sugar stops your natural insulin production and diabetes begins, like too much sunlight on your skin causes cancer, the more morphine you're prescibed the more it fizzles out as pain relief, you drop acid one day and trip balls, do it the next day and nothing much happens. It's kinda one of the basic rules of brain chemistry: the brain is always trying to maintain homeostasis, so if you push a particular neural system too far in one direction, it bites back with downregulation e.t.c. To try and get back to "normal".... Nothing new here. Responsible choice hit the nail right on the head with granny's quote.

[freakazoid]

I like Harry Callahan's quote: "a man's got to know his limitations"

[mu!]

There are a few things that I'd like to know about in this study.

Is 11 a big enough sample size for a study like this?
Do any of the cannabis users have a history of polydrug use or have they only ever smoked pot?
Is amphetamine-mediated dopamine release a good way to measure general dopamine release?

 

Without knowing the answers to any of those questions it'd be hard to jump to any hard conclusions. It is good to see more research done in this area though, even if it appears to confirm "what everyone already knows, dur." There's a difference between the likes of anecdotal evidence, conventional wisdom, and actual science-based evidence. Sure, granny might be able to give you a general rule of thumb like 'all things in moderation' but she won't be able to give you exact data on what is happening to you when you overdo it, or what you should do once you've gone off the deep end on a particular drug.

 

How could more information and research on plants be a bad thing?

[-RC-]

^ When it is used to justify further restrictions and reduction of personal freedoms, which I reckon this kind of study is aimed at provoking.

[Francois le Danque]

I like Harry Callahan's quote: "a man's got to know his limitations"

 

well....do ya?     punk

[stonewolf]

Twenty cones a day can negatively effect you?!!!?

Stop the presses.

The shear amount of research funding that goes into proving the obvious is depressing.

It's not like they could have extrapolated from a natural experiment with hundreds of millions of participants spanning fifty years.....oh wait.

[Change]

It would be great if someone could post up the full paper, id love to read how the results were collected. 

 

When i first read the article, i thought, wow long term cannabis use might be a helpful treatment for schizophrenia considering schizophrenia is said to be associate with increased levels of dopamine. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC33999/ 

 

So i had a look at the lead author of the paper and it looks like she has dedicated her research career to schizophrenia related spectrum disorders, and addiction.

 

Anissa Abi-Dargham, M.D., is Chief of the Division of Translational Imaging in the Psychiatry Department of the Columbia University College of Physicians and Surgeons

 

https://en.wikipedia.org/wiki/Anissa_Abi-Dargham

 

 

^ When it is used to justify further restrictions and reduction of personal freedoms, which I reckon this kind of study is aimed at provoking.

 

I think its safe to say this author has bigger and better things to do then try and justify further restrictions and reductions on your own personal freedom.

 

 

[-RC-]

I never said she didn't.

 

I said orgs like the APA are pieces of shit, and all of the research they present which furthers pharmaceutical interests, by way of casting aspersions upon alternative medicines, should rightly be taken with a shitload of salt. Or something like that...

[BedOSpines]

Cough*

[BedOSpines]

sounds kinda like temporary withdrawal symptoms *shrug. 

[BedOSpines]

what cigarette smoker smokes less than twice a month?

[-RC-]

CONFLICT OF INTEREST

Dr Haney has received partial salary support for investigator-initiated studies from

Insys Therapeutics Inc and Lifeloc Technologies and has served as a consultant to

Aelis Farma and Health Advances LLC. Dr Kegeles has received research support from

Amgen. Dr Slifstein has received research support from Forest Laboratories, Pierre-

Fabre, CHDI, and Otsuka and has provided consultation for Amgen. Dr Abi-Dargham

has received research support from Takeda and Forest Pharmaceuticals and has

served on advisory boards for Roche, Forum, and Otsuka. The remaining authors

declare no conflict of interests.

[Slocombe]

If the same kind of research was run into the effects of gambling/porn/sex/internet addiction, they'd probably find something similar... I'm sure the study was conducted soundly... I just think there are more useful lines of enquiry. Bit of a waste of money beyond the propaganda value