Study: Long-term marijuana use changes brain's reward circuit

Study: Long-term marijuana use changes brain's reward circuit
Dr. Francesca Filbey, director of cognitive neuroscience of addictive behaviors at the Center for BrainHealth, and her research team examined the effects of long-term marijuana use on the reward system in the brain. Credit: University of Texas at Dallas

Chronic marijuana use disrupts the brain's natural reward processes, according to researchers at the Center for BrainHealth at The University of Texas at Dallas.

In a paper published in Human Brain Mapping, researchers demonstrated for the first time with functional magnetic resonance imaging that long-term users had more activity in the mesocorticolimbic-reward system when presented with cannabis cues than with natural reward cues.

"This study shows that marijuana disrupts the natural reward circuitry of the brain, making marijuana highly salient to those who use it heavily. In essence, these brain alterations could be a marker of transition from recreational marijuana use to problematic use," said Dr. Francesca Filbey, director of Cognitive Neuroscience Research in Addictive Disorders at the Center for BrainHealth and associate professor in the School of Behavioral and Brain Sciences.

Researchers studied 59 adult marijuana users and 70 nonusers, accounting for potential biases such as traumatic brain injury and other drug use. Study participants rated their urge to use marijuana after looking at various visual cannabis cues, such as a pipe, bong, joint or blunt, and self-selected images of preferred fruit, such as a banana, an apple, grapes or an orange.

Researchers also collected self-reports from study participants to measure problems associated with marijuana use. On average, marijuana participants had used the drug for 12 years.

When presented with marijuana cues compared to fruit, marijuana users showed enhanced response in the brain regions associated with reward, such as the orbitofrontal cortex, striatum, anterior cingulate gyrus, precuneus and the ventral tegmental area.

"We found that this disruption of the reward system correlates with the number of problems, such as family issues, individuals have because of their marijuana use," Filbey said. "Continued marijuana use despite these problems is an indicator of ."

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More information: Francesca M. Filbey et al. fMRI study of neural sensitization to hedonic stimuli in long-term, daily cannabis users, Human Brain Mapping (2016). DOI: 10.1002/hbm.23250
Journal information: Human Brain Mapping

Citation: Study: Long-term marijuana use changes brain's reward circuit (2016, June 6) retrieved 23 October 2019 from
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Jun 06, 2016
59 users? Really. We are meant to believe this crap? Try using something people wanted instead of fruit. Maybe an Xbox would show some interesting things. To small a sample group and to few variety in the testing subjects. I am guessing this is another attempt to buy science to match the political agenda.

Jun 06, 2016
Did they take into account that the population from which they are taking specimens has been brutally traumatized by violent,alcohol-related crimes - prime causes of PTSD, over the past 50 years? The fact is, millions of those have been using cannabis to treat alcohol-related traumatic stress, even though multitudes of them do not even know why they are using it, nor that they even have traumatic stress. They just know they have been chronically stressed and that cannabis treats their symptoms.

Jun 06, 2016
I really couldn't agree more with the two comments above. You have used a small test group in an area known to have more traumatic problems than most and sensationalised it in print . I would be ashamed to print such bull. You as a journalistic entity should tell your masters to stop the cowardly attacks on a plant with medical benefit.

Jun 06, 2016
I live in Dallas and this is the reason I would never pay the University of Texas Dallas money for an "education."

I could take pictures of cupcakes and put them next to pictures of fruits and trigger precisely the same reactions in the brain as your study produced. The "scientists" who used the university's money for this "study" should have their credentials stripped away.

Jun 06, 2016
I couldn't agree more with the other commentators.

Instead of something like an X-Box for adults, perhaps a Virtual Reality headset would have been more appealing, for example.

This just proves the old proverb, "You cannot believe everything you read."

Twisted stories are easy when you have the keys to the world wide web.

I am not saying this study's sole intention was to mislead the public, but let's face it, we don't have to be scientists to see through this one.

Jun 06, 2016
Government and Corporate lies are unacceptable at this juncture. They have lied about Marijuana for almost 100 years now. Unless they can prove these studies are not influenced by Government and Corporate lies, I chose to believe the truth of empirical data and not their lies. .

Jun 06, 2016
Where are the studies on how harmful alcohol is to us, and eating too much, and running to much, and any exercise, too much, and too much of this, and too much of that? This research is pointless. Too much of ANYTHING is bad.

Jun 06, 2016
Wernicke's encephalopathy and WKS is most commonly seen in people who are alcoholic, and only 20% of cases are identified before death. This failure in diagnosis of WE and thus treatment of the disease leads to death in approximately 20% of cases, while 75% are left with permanent brain damage associated with WKS.[2] Of those affected, 25% require long-term institutionalization in order to receive effective care or "Wet Brain" as well as Fetal Alcohol Syndrome both being a threat to the public welfare. Yet the drug alcohol with few exceptions will not have warnings either posted or on packaging. Get ready for an onslaught of "Shocking Studies" and folks with drinks in hand and nodding with agreement .

Jun 06, 2016
This article's headline is purposely deceiving. So right off the bat ya have to wonder about motivations. Author certainly knows that the low amount of subjects in this research means it can only show that further research may be warranted. Other than that, only assumptions can be ascertained for follow up research to delineate further. This study was incapable of determining whether or not the subjects mesocorticolimbic reward system was different to begin with and that's the very reason an addictor was inexorably sought out. Others have called it a hypo-active endogenous reward system that is the predictor of addictor use / substance abuse. Certainly this author & the researchers knew of this going in yet no mention of this. Why is that? I'm sure exogenous drugs alter the brains chemistry. Seems safe to assume that. But to insinuate that its a causation not an association is disingenuous at best.

Jun 06, 2016
All BS studies! "Reefer Madness"! I see nothing about the real epidemic in this country which is ALCOHOL! What pathways and reward system does it disrupt? Since it is highly addictive, and a systemic poison, I would think quite a few! Who would drink that garbage? I'll stick with my herb, thank you!

~The Shaman~

Jun 06, 2016
In short, more "reefer madness". The harm caused by the penalties incurred by the prohibition of this plant vastly exceeds the effects of it's use and I find that harm to be at a criminal level. Maybe we should be discussing this over a couple of pints of beer?

Jun 06, 2016
yeah..ok...i bet if you presented these marijuana users with sex instead of fruit, i bet your results would have been A LOT different Long term use of tobacco will give you all kinds of health issues..long term use of alcohol will give you cirrhosis of the liver. Long term use of pharmaceuticals will make you an addict and you have a high probability to overdose. its amazing how many of these "studies" have popped up since over half the country now has some form of legal marijuana use. how about you do studies on how marijuana helps veterans with PTSD? or something of the like. i think that would be better use of yours, and our time

Jun 06, 2016
As expected, before an important legalization vote for cannabis, the anti-pot propaganda troops are coming out in full force. But truth will prevail.

Jun 06, 2016
Didn't they have a study like this about a year ago, saying it made a part of the brain smaller, but with more connectivity? They never said it was harmful, they just presented it so it would seem like it was.

Jun 08, 2016
LOL, this study is literally hilarious. I have no clue what they are trying to actually imply by this study.

"We found that this disruption of the reward system correlates with the number of problems, such as family issues, individuals have because of their marijuana use," Filbey said. "Continued marijuana use despite these problems is an indicator of marijuana dependence."

So wait, would this mean that MJ is similar to alcohol? The most common cause of death in the United States, which is also completely legal for anyone over 21? Are they actually trying to say that MJ dependence is a more serious matter than alcohol dependence?

LMAO, pathetic. Maybe they should consider comparing and contrasting alcohol and MJ, then let us know which one they feel has a more detrimental impact on a persons life 'over a long period of time'. /smh at these scientists that did this study..

Jun 14, 2016
Is this really physics, you guys really reach. Get back to your field, the is more medical than, physics. This site is very borderline, to being non sense . Stop the blow up, nonsense is this not a site backed by physics ? I'm leaving now !

Jul 05, 2016
Fruit??? Try something that will actually get people excited to get a real idea.

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