Why marijuana affects different people differently

Why marijuana affects different people differently
Credit: University of Western Ontario

For some people, marijuana causes a rewarding high. For others, it produces serious psychiatric side effects.

Whether a person enjoys the experience or adverse effects from cannabis may well be decided by which region of the it's acting upon, Western researchers have determined.

The psychological effects of can differ between individuals: some experience highly rewarding effects which may lead to dependence on the drug, while others may experience paranoia, cognitive problems or an increased risk of developing schizophrenia.

"Until now, it was unknown which specific regions of the brain were responsible for these highly divergent effects of marijuana," said Steven Laviolette Ph.D., Professor at Western's Schulich School of Medicine & Dentistry.

"Translational rodent research performed in our lab has identified highly specific target regions in the brain that seem to independently control the rewarding, addictive properties of marijuana versus the negative psychiatric side-effects associated with its use."

The study, led by Laviolette and postdoctoral fellow, Christopher Norris, Ph.D., is newly published in Scientific Reports and reveals critical new insights into how marijuana can produce such highly diverse psychological effects in different individuals.

By looking at THC's effect on a rat brain, the researchers showed that THC, the main psychoactive compound in marijuana, can produce highly rewarding effects in the front-most part of a region of the brain called the .

The study showed that THC in this brain area not only produced highly rewarding effects in and of itself, it amplified the addictive properties of opioid drugs like morphine and increased reward-related activity patterns in the neurons.

By contrast, THC in the posterior area of the nucleus accumbens region produced highly .

These included more schizophrenia-related cognitive and emotional symptoms and patterns of neuron activity similar to those found in people with schizophrenia.

"These findings are important because they suggest why some people have a very positive experience with marijuana when others have a very negative experience," said Norris.

"Our data indicate that because the reward and aversion are produced by anatomically distinct areas, the different effects between individuals is likely due to leading to differential sensitivity of each area."


Explore further

Researchers reverse the negative effects of adolescent marijuana use

More information: Christopher Norris et al. The Bivalent Rewarding and Aversive properties of Δ9-tetrahydrocannabinol are Mediated Through Dissociable Opioid Receptor Substrates and Neuronal Modulation Mechanisms in Distinct Striatal Sub-Regions, Scientific Reports (2019). DOI: 10.1038/s41598-019-46215-7
Journal information: Scientific Reports

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Jul 08, 2019
I don't consider mj to be addictive. Unless your definition of addictive is wanting to repeat something that makes you feel good to feel good again. In which case the word is meaningless since it would encompass everything that makes someone feel good.

I use the word to mean a chemical dependence that makes you feel worse anytime you don't have it in your system than you would if you never had it.

Mj doesn't do that. There's no negative incentive to keep using if you stop. You just stop. This is one of the first things kids learn about the fecitous nature of the war on drugs that makes them not believe in any of it... Even the true things.

Jul 08, 2019
Mj causes me severe anxiety reactions and no high at all. It is interesting to find out that im not alone and that it can cause bad reactions in some people. Great article

mqr
Jul 08, 2019
Cannabis allows people to access their unconscious, therefore it must produce discomfort in many individuals, the more has in their unconscious that they do not want to access, the more anxiety and problems cannabis will cause. Very similar to meditation.

The problem is blaming the plant or meditation.

Jul 08, 2019
Marijuana addicts always insist marijuana is completely safe. They said it has no adverse effects. They say it cures all diseases. They said it did not cause any psychological problems. And "scientists" for decades agreed whole heartedly. "Scientists'" lies apparently went a long way toward the sickness of states' "legalizing" "recreational" marijuana. The damage is done and, now, "scientists" are admitting the truth slowly.

Jul 08, 2019
In which case the word is meaningless since it would encompass everything that makes someone feel good.


False dichotomy. Drugs operate on the same reward pathways as anything else, but they give an artificially high reward which biases the brain's prioritization towards taking the drug even when it has no use, or it has harmful effects. That's what addiction is: preferring the easy reward and choosing it over and over, even if it's harming you.

For example, you could be doing all kinds of things to improve yourself or get things done, but instead you're smoking weed, stuck to the couch watching bad television because the drug makes you stupid enough to enjoy it. When you're sober, you don't feel any sort of jitters - weed isn't physically addictive like heroin or nicotine - but you do feel bored because things don't feel as good as when you're high, so you smoke again, and again, and again...

When you're high, you can eat oatmeal porridge and go "Mmmm..."

Jul 08, 2019
Cannabis allows people to access their unconscious, therefore it must produce discomfort in many individuals


Or maybe it's just chemically incompatible with many people, and causes anxiety and paranoia directly by messing up their brain chemistry.


Jul 08, 2019
It isn't a false dichotomy, I just don't find the definition I described as being useful to convey any meaningful information that differentiates an addiction from just enjoying doing something.

Even your definition prefaced that it had to do harm to be called an addiction. Still harm is, a too vague use of the word since the same amount could be used in the same frequencies for the same reasons but harm can vary. Because the harm here is less about chemical and biological reactions to the drug and more about your personal decisions around using it. The people impacted negatively with paranoia and anxiety don't continue using it... So aren't a part of the discussion of addiction.

Jul 09, 2019
Frankly, a lot of people simply enjoy the high that they get from it. And given the oppportunity they will repeat the experience. If they really enjoy it, then why on Earth wouldn't they want to do it again?

It's no different from many other things people do repeatedly for no other reason than because they like it. Many of which are harmful if done to excess. Eating, drinking alcohol, sunbathing until your skin is leathery, binge watching TV, or any one of countless human activities.

Ever since humanity has existed people have self medicated with whatever happened to work for them individually, including taking things that altered their perception. Which actually makes doing it fundamental human right.

There is nothing that will be the exact same for everyone. Some will love it and some will hate it. So, like any other voluntary activity, if you don't like it then don't do it. Find what works for you as an individual as is your right and do that.

Jul 09, 2019
Different reactions, yes, but the same condition of being separated from reality. Sounds like evolutionists to me. I can't talk from experience as I have never taken drugs, and haven't even smoked a single cigarette. But I am one of the happiest people around.

Jul 09, 2019
First, this study is on rats, not humans, so the results are of unknown significance.

Second, this study is on THC, while humans consuming cannabis will consume hundreds to thousands of other chemicals in addition to THC, some of which are physiologically active, such as CBD. These other chemicals may modify the effect of THC.

Third, this study concludes that THC effects different areas of the rat brain differently. So what?

Fourth, I feel sorry for the rats who were harmed for this useless experiment.

Jul 09, 2019
"By contrast, THC in the posterior area of the nucleus accumbens region produced highly adverse effects.

These included more schizophrenia-related cognitive and emotional symptoms and patterns of neuron activity similar to those found in people with schizophrenia."

How can anyone determine this from rats? And if rats can experience emotions and mental distress as humans do, then how can we do these hideous experiments on them? What kind of people are these animal researchers?

Maybe the researchers should simply smoke the weed they got for the experiment and chill.

Jul 09, 2019
Even your definition prefaced that it had to do harm to be called an addiction.


No. You missed the point: an addiction is a condition where a person is compulsively repeating a behavior because of a false reward - even if it's not immediately harmful. The point is the compulsiveness, not the harm.

It's no different from many other things people do repeatedly for no other reason than because they like it.


The difference with addiction is that when the habit does turn harmful, you'll continue doing it regardless, because it's not really under your control. While the going is good, it merely seems like you're on top of things.

It's been proven with alcoholics that the difference is their brain chemistry, where alcohol gives a much higher reward compared to normal people. It feels "too good", so the brain starts to value getting drunk over anything else and generates a compulsive craving. The person then rationalizes their behavior to justify the drinking.

Jul 09, 2019
Typical rationalizations include:

Ever since humanity has existed people have self medicated with whatever happened to work for them individually


The question is, medicate for what? Medicine isn't a diet - it's supposed to cure you of some ailment or problem. If the drug works, then the person would eventually stop taking it because they don't need it anymore. If the drug won't get rid of the problem, the non-addicted person would eventually stop anyways and seek other solutions.

The point with "self medicating" with psychoactive drugs is rather that the problem is invented in order to justify taking the medicine, because the person is addicted and trying to maintain a positive self-image by rationalization. Alternatively, the drug causes the problem in the first place. Such as getting depression, which then requires you to use the drug to pick you up.

Jul 10, 2019

No. You missed the point: an addiction is a condition where a person is compulsively repeating a behavior because of a false reward - even if it's not immediately harmful. The point is the compulsiveness, not the harm.

The difference with addiction is that when the habit does turn harmful, you'll continue doing it regardless, because it's not really under your control. While the going is good, it merely seems like you're on top of things.

So in what way is mj addictive? There is no compulsion to use and if your brain chemistry makes the experience negative, there's nothing incentivizing you to continue using it. You just stop. The only way it falls under addiction is if you categorize it under a habitual addiction like OCD. Which is a completely different thing than the article implies. I'm not a fan of wishy-washy definitions that are defined by subjective terms like harm when harm is defined so loosely it encompasses all aspects of life and not just biological.

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