Alice G. Walton

Alice G. Walton, Contributor

I cover health, medicine, psychology and neuroscience.

1/11/2012 @ 10:49AM |45,665 views

The Neuroscience of Pot: Researchers Explain Why Marijuana May Bring Serenity Or Psychosis

English: A photograph of hemp (Cannabis sativa...

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According to the experts, and to people who use it, pot can have widely disparate effects on people’s behavior, depending on…well, that part is still a bit unclear. Marijuana has been shown to have both anxiolytic (anti-anxiety) effects and to induce anxiety and psychosis in certain people. In schizophrenics, it can increase symptoms, and in healthy people it can increase the risk of schizophrenia. Now, new study shows that the two active ingredients in pot, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) may have quite opposite effects on the brain – and behavior – and could explain why pot’s effects can be unpredictable.

In the new study, the researchers had 15 men who were relatively unseasoned pot users take capsules containing THC, CBD, and flour (placebo) on each of three occasions. The participants then took simple computer tests in which arrows, pointing either left or right, flashed on the screen; the men had to respond based on their direction. Occasionally, an “oddball” arrow was thrown in to the sequence, which was at a 23-degree angle.

This setup allowed the researchers to compare the men’s reactions to usual vs. oddball stimuli, and to see how the various chemicals affected it. How people react to mundane environmental cues vs. the unexpected ones is thought to be linked to mental health, and therefore, to disorders. So, the men’s reaction times were measured, and their brains were scanned with fMRI to see what was going on neurologically. Their psychotic symptoms were also compared across conditions.

The men who had taken THC had more psychotic symptoms like altered thinking (paranoid and delusional thoughts) than men who’d taken either CBD or placebo.

The THC also had a greater effect on reaction time to the standard, rather than the oddball, conditions. This suggests that THC could change what people see as important environmental stimuli (more on this later). Men who had taken the THC also had less activation in the caudate nucleus: and the less activity in the area, the more marked the men’s psychotic symptoms and affected their reaction times. Alterations in the activity in the striatum and prefrontal cortex also suggested a possible mechanism for the increase of psychotic symptoms.

Taking CBD, however, had the opposite effect of THC. It tended to speed up response time to the oddball stimuli, compared to the standard ones, which suggests that it works with our natural tendency to react to unexpected stimuli, rather than against it. And the brain regions that were activated after CBD ingestion were largely counter to those activated with THC. Previous research has suggested that CBD has antipsychotic effects, and this seems to be supported by the current study.

So what’s the relationship between response to arrows on a screen and psychotic symptoms? Normally, people tend to react to out-of-the-ordinary stimuli over the usual ones. In this study, however, people on THC had boosted responses to the mundane stimuli, and were less responsive to the unexpected ones. In the real world, if one has problems ignoring ordinary stimuli in the environment – and even has a ramped-up or atypical response to them – this could creep into the territory of hallucination. Earlier studies have found links between chronic marijuana use and an increased risk for developing psychotic symptoms. Of course, it’s hard to tell whether marijuana use leads to mental health problems or already having mental health problems leads to increased marijuana use, but this and other studies suggest that it’s more likely the former case.

On the other hand, CBD seems to counter the effect of THC, and could (possibly) be used as an antipsychotic. The team’s earlier work actually showed that pretreatment with CBD can block the psychotic effects of THC administration.

The problem is that most people don’t ingest CBD or THC capsules in real life. They smoke pot, which includes both chemicals. Therefore, the study doesn’t quite explain why taking in both chemicals in at the same time would have different effects in different people (or different effects in the same person on different occasions). For example, why some people are more susceptible to the negative effects of the drug than others is still unclear, but it may be due to the patterns of the different cannabidiol receptors in the brain or other differences that have yet to be determined.

The study does help explain why synthetic marijuana has been linked to more adverse effects than natural cannabis. Synthetic forms of the drug, like K2, which have been associated with more hallucinations, agitation, and ER visits, are made largely of chemicals that are thought to mimic THC.

Future studies will have to look into some of these remaining questions, but this study makes a good stab at explaining why marijuana can lead to such different experiences in people who use it.

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  • seanzenneth seanzenneth 2 years ago

    Great article! The hope is that this article will raise awareness of the general public who seek Marijuana. Today, this subject is widely introduced and talked about and it’s always great to read articles backed with research. On the study we conducted over the past three months, we have been able to find a connection between marijuana and herbal incensewhereby this new substance called herbal incense is replacing the actual marijuana due to many reasons.

  • “…other differences that have yet to be determined.”

    Good quality weed give a better high.

  • Andrew Andrew 2 years ago

    Good Article! We’ve recently been studying the effects between marijuana and a new substance called herbal incense. It seems to flood serotonin to the human brain, creating euphoria

  • James Dalton James Dalton 1 year ago

    Thought I’d share this article since it’s related to this post:

    Does Medical Marijuana Help Treat Diarrhea?


  • James Dalton James Dalton 1 year ago

    Thought I’d share this article since it’s related to this post:

    Does Medical Marijuana Help Treat Diarrhea?

    Well, we’ve all had it, that’s for sure. For those of you who are not familiar with this river of fecal matter, think of diarrhea as a casual turd, not very compact but quite fluid. This turd flows around the end of your digestion system in a very loose manner, resulting in a watery stool. Diarrhea rarely comes alone and is usually combined with cramps and in more severe cases – fever. It may be a result of an infection, heavy drinking or just bad food. herbal incense reviews of some of the best known herbal incense brands show that some incense products can provide health benefits.

  • James Dalton James Dalton 1 year ago

    I agree with many of points mentioned here. As I have said before, I’m very much for the medical benefits of marijuana. I definitely agree that marijuana can bring Serenity or Psychosis as the title suggests here. However, there are many brands of herbal incense that have caused many issues for the public. I’m hoping this article will raise some awareness.

  • JohnGalt JohnGalt 1 year ago

    As only a casual user of pot when it “magically” appears at a party or elsewhere, I appreciate this article for laying out the direction of research into this area. I also agree with other posters that marijuana probably does not cause mental disorders, though it could cause them to be exaggerated. I expect my casual use will be zero from this point forward. Though I suppose I could be loosely put into the Type A category, I technically have super-high functioning ability on both sides of my brain and can perform at a level near the positive tail of the distribution, for both analytical and creative tasks (or you could say math and English, whatever you want to call it). I don’t know a better way to describe it at full effect (i.e., both sides of the brain at nearly 3 standard deviations above the mean, 24 hours a day), than to say that a traditional diagnosis would probably call it schizophrenia. But I do know how it feels – think of your brain at full power, unable to switch down, all night, and trying to sleep through both sides fighting for control over thoughts that are nearly polar opposites. Oh, and it has the added bonus that during the day, when doing typical day to day activities, you will appear hyped up enough that most people will think that you’re on drugs, even if you’ve never touched a drug in your life. Welcome to my high school and college years. Flip a coin and decide which is the better one to tell people – yeah, you’re right, it’s drugs; or no, you’re wrong, I’m mentally ill because my brain can perform at nearly genius level on both sides.

    So for most of my adult life, I have pursued a single avenue professionally, focused on left-brain activities in math and finance. And I found ways, or more correctly my brain did, to shut down much of the crosstalk coming from the right side. And I could finally sleep and function in the real world like a typical person.

    And I even smoked pot a scant few times. I’ve never had an issue with marijuana in the past, other than it would either make me really baked (the sensation of weightlessness and time suspension) or just really tired. But it never made me go off the deep end. Until recently. In the last year, on two occasions, I’ve had what most regular users would probably consider a warm-up round, and all hell broke loose. The first time was like an acid trip from hell (I’m guessing, I’ve never actually taken acid) – spots, hallucinations, crying uncontrollably, loss of balance, extreme paranoia, and on and on. The second was less psychedelic but still not like a typical marijuana trip at all, instead more like a pure amphetamine right into the bloodstream, unable to slow down speech and reacting to even the slightest light, sound or movement around me. It was less disorienting at the time, but still quite alarming after the fact. Obviously, one never knows for sure what is in pot, but I have no reason to believe it was cut with some other drug. But this coincided with my decision to let the right side of my brain get its due, and unleash my creative side, so I think there’s something there with the chemistry of the two sides of the brain, and their interactions with the active ingredients in pot. It would be interesting to know how the test subjects’ brains were oriented, i.e., right-dominant or left-dominant, or both equal. I’m comforted by the article that there is some small percentage that have a reaction like this, but it’s not just a minor one. My friends believe strongly that pot is the most dangerous drug I could take, because of the way it interacts with my brain/brain chemistry.

  • Marijuana probably does not induce anxiety, but the fact that it’s illegal does. The only reason one would get anxiety is from fear of police coming to get that person. Cannabinoids are a natural substance that is naturally in our body. Marijuana is an entheogen, not a drug. Drugs you can die from. Marijuana you can’t. Supposedly, you have to smoke 1500 pounds of cannabis to die from it, after getting extremely crazy hallucinations. But nobody’s ever done this, nor has anybody ever died from cannabis. There is two types of entheogens. Herbal entheogens and “medicinal” entheogens. Herbal you can go willy nilly on, like marijuana, psilocybin, salvia divinorum, et cetera, though it may be psychologically unbearable. Medicinal, though technically all entheogens are medicine, are those plants that one can overdose on, like ergot, lysergic acid diethylamide, et cetera. So the reason marijuana would cause psychosis is because of either fear of the police, or, another reason not mentioned, is the substances that the dealer laced the marijuana with. Real conclusions can come from lab-grown cannabis for the very purpose of experimentation, done on people that have anxiety, and those that don’t. This is one reason of many that marijuana should be legalized, because it would control the plant, though I believe that all should have it willy nilly, it is a step towards that, better than nothing, it would reduce cartel violence, cut spending on prisons, keep it from youth by controlling it (alcohol is harder to get than illegal drugs and enthegens, for children, because someone can willy nilly go on the street with money, or get with their friend who has connections and get it from their connection, in which the connection has no ID check, and just takes the money. With alcohol, you have to have a stupid brother, the 21 year old super senior, or your alcoholic parents give you access to alcohol without authoritative supervision. This makes it really hard to get alcohol. With illegal substances, they’re easier to get.), and being able to have labratories conduct authentic researching. Marijuana should be legal anyway, because it was immense corporate propaganda that got it illegal in the first place, in 1937, and that kept it that way. Before 1920, marijuana wasn’t any more condemned than coffee. Nobody saw anything wrong with it, and all was good. Except the pharmaceutical companies, and the manufacturing companies had a despising view towards its brother hemp.

  • Some people cant eat peanut butter or strawberries due to food allergies~ so it makes sense that some people cant smoke pot without bad reaction.

  • Doug Roehr Doug Roehr 1 year ago

    Way to gloss over a big issue. THC and CBD are not ‘ingredients’. the main ingredients are sun, dirt, water, fresh air. You learned in the study about one little sample of cannabis they got their hands on, it means nothing. keep going over the old beliefs of ‘reefer madness’.
    You wont have to worry about the poor and sick people who can benefit from a totally unique natural resource, and won’t get your hands dirty.