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Does marijuana actually boost creativity?

Study under review: Cannabis and creativity: highly potent cannabis impairs divergent thinking in regular cannabis users.

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Introduction

Steve Jobs once said that “marijuana and hashish … make me relaxed and creative.” And many people agree with his assessment. One study[1] found that over 50% of users report enhanced creativity when using marijuana. But, Steve Jobs was wrong about things before (the Apple Lisa, anybody?). Could he have been wrong about marijuana enhancing creativity as well?

Researchers know enough about the brain to take a decent stab at predicting how marijuana may affect creativity. The story starts with the neurotransmitter dopamine and its influence on two cognitive processes first fleshed out in the 1960s, a decade of great creativity!

While creativity is a hard thing to measure objectively, some components of it are being teased out. Specifically, two cognitive processes are thought to play a strong role in creativity. They are called convergent and divergent thinking. Divergent thinking is best described as the skill behind brainstorming. It’s being able to explore options through loose associations to generate novel ideas. Convergent thinking works in the opposite direction: it takes a bunch of loosely-organized ideas and finds a common thread between them.

There is a common thread winding its way through these thought processes and dopamine. Dopamine is often thought of as the “reward neurotransmitter” (although this is a major overgeneralization[2] because dopamine has multiple[3] functions). However, it also seems to have a role in the neuroscience of creativity. Specifically, one study[4] found that dopamine has a negative linear correlation with convergent thinking, whereas it shows an “inverted U” shape correlation with at least one aspect of divergent thinking, where too much or too little harms it, but a middle amount is just right.

Dopamine: a double-edged molecule

The trope of the mad artist is worn out enough to have its own TV Tropes page. While this is clearly an oversimplified stereotype, there is an interesting connection to be found here.

Dopamine activity seems to correlate with creativity, as mentioned in the introduction. However, it is also related to schizophrenia. One study found that creative people without schizophrenia had low dopamine receptor levels in their thalamus (but not the striatum; the science is still young on this), which is also found in some people with schizophrenia. The authors of this study suggest that low dopamine receptor levels lead to less filtering of information. In people without schizophrenia, this can lead to creative, divergent thinking. In people with schizophrenia, it can lead to troubling symptoms.

The main psychoactive ingredient of marijuana, delta-9-tetrahydrocannabinol (THC), is known to stimulate release of the neurotransmitter dopamine in a part of the brain called the striatum[5], a part of the brain that has been seen to be involved in creative activities like writing[6] (and also addiction[7]). Chronic marijuana use, however, may lead to depressed dopamine activity[8].

The authors of the current study put together the facts about dopamine, marijuana’s effects on it, and creativity to suggest a hypothesis about how marijuana may affect divergent and convergent thinking. Since long-term cannabis users would have depressed dopamine activity, their divergent thinking before marijuana use would be on the left hand side of the inverted “U” shaped curve. For them, acute use of marijuana may push them to the right on that curve, improving divergent thinking. Convergent thinking, however, is negatively correlated with dopamine activity, so marijuana use should hamper this aspect of creative thinking in any marijuana users, regardless of how long they’ve used it. These relationships are summarized in Figure 1.

Figure 1: Theoretical predictions of how dopamine activity is related to creativity

The goal of the current study was to put this hypothesis to the test.

Two aspects of creativity are related to dopamine activity in the brain. Divergent thinking, the skill behind brainstorming new ideas, may get worse with very low or very high dopamine activity, and is best in the middle range. Convergent thinking, the skill behind unifying ideas into a coherent whole, worsens as dopamine activity increases. Since long-term marijuana users have depressed dopamine function, use of marijuana in this population could improve divergent thinking while worsening convergent thinking. This hypothesis was put to the test in the current study.

Who and what was studied?

A total of 54 healthy Dutch people (six women and 48 men) in their early 20s who regularly used marijuana were included in this study. “Regular use” was defined as consuming marijuana at least four times per week for the past two years. “Healthy” here meant that the participants did not have significant mental or physical disorders, did not abuse alcohol, were not on any psychotropic medications, and did not use any other drugs recreationally. People who smoked cigarettes were included in the study.

After recruitment, the participants were then randomized to inhale vaporized marijuana that contained one of three levels of THC. The vaporizer they used (a Volcano-brand vaporizer, depicted in Figure 2) had a large balloon attached to it which filled with the vapor, and the participants were asked to inhale the contents of the balloon deeply and hold their breath for ten seconds before exhaling. It’s a pretty big balloon, so it took several inhalations to completely consume the balloon’s contents.

Figure 2: The Volcano vaporizer

The total amount of THC delivered to each participant in the three groups was 22 milligrams (high dose), 5.5 milligrams (medium dose), or almost 0 milligrams (placebo). Acknowledging that not all the THC in the plant is vaporized, and not all of the inhaled THC is absorbed through the lungs, the researchers estimated that the actual doses absorbed were eight milligrams, two milligrams, and zero milligrams, respectively. The participants and experimenters were blinded to what dose of THC was being delivered.

The study participants were then asked to report their subjective feelings six minutes after completely consuming the marijuana. They then completed two tasks to measure their creative thinking 35 minutes and then 60 minutes after consuming the marijuana, and given 10 minutes to complete each task. But ... how can you measure creativity? Well, psychologists, being a somewhat creative bunch themselves, have come up with a few tests to do so.

One of the tests was the Alternate Uses Test (AUT), which measures divergent thinking, an aspect of creativity. The AUT asks people to generate as many as possible uses for a common household items as they can think of in a given span of time. For instance, a pen can write, hold a door open, be used as a bookmark, be melted and molded into a shape, etc. The answers were then rated by two independent reviewers blinded to treatment conditions according to four different criteria: fluency, flexibility, originality, and elaboration. The scores highly correlated with each other, which suggests that the tests were rated reliably.

The other test was the Remote Associates Task[9] (RAT), which is considered a measure of convergent thinking. This task involves giving a group three words and encouraging them to try to find a fourth word that links them. One example is “back, go, light.” The fourth word for this set is “stop.” Since the RAT has “objective” answers, it is easier to come up with a final score for it than the AUT. You just count the number of right answers.

The tests were administered in a random order to each participant to make sure the order of administration didn’t affect the results. Also, after each creativity test, the experimenters again asked the participants to rate their subjective feelings.

This study recruited 59 people who were young, healthy, and frequently used cannabis. Researchers intended to test the effect of cannabis on creativity. Participants were randomized to inhale marijuana which had either high, medium, or almost no THC. After consuming the marijuana, they were administered two tests of creativity: the Remote Associates Task (RAT), which measures convergent thinking, and the Alternate Uses Test (AUT), which measures divergent thinking. Their subjective feelings were also measured throughout the experiment.

What were the findings?

The study’s findings are summarized in Figure 3. The three treatment groups did not differ in convergent thinking as measured by the RAT, indicating that the THC content of marijuana did not affect remote associations in this population.

Figure 3: Summary of results

Also, there was no difference between the placebo and medium-dose group’s performance on any of the four subscores of the AUT, indicating no effect on divergent thinking at this dose of THC. However, the high-dose group performed significantly worse on three of the four AUT subscores, with no difference between the three doses for the elaboration subcategory.

Before they used marijuana, the participants in this study performed similarly[4] to people not under the influence of any substances on the AUT and RAT.

In terms of subjective feelings, people felt higher when they inhaled vaporized marijuana with THC in it (surprise, surprise), and also said they had higher “good drug effect” scores. A little more surprisingly, there was no difference in either of these scores between the medium- and high-dose THC groups. Also, people in the high-dose THC group reported experiencing significantly worse drug effects compared to the medium-dose and placebo groups. The latter two groups didn’t differ statistically from each other in terms of bad drug effects. Finally, THC level did not affect measures of mood, and mood did not change significantly over time.

Convergent thinking as measured by the RAT was not affected by THC at any dose. Divergent creative thinking was unaffected at medium doses of THC, and made worse in three of four subcategories of the AUT at high doses, with no effect on the fourth category of elaboration.

What does the study really tell us?

The study provides some evidence against the view that marijuana enhances creativity. Instead, it either seemed to have no effect or a negative effect. But, as usual, there are a lot of caveats to this statement.

First, the measures of creativity used in this test were all based on word association on the written page. It is not immediately clear if this relates to creativity in other domains, such as the visual arts, dance, music, or the spoken word. There is some evidence along with varying hypotheses that address how related different types of creativity are, but results are quite mixed, and studies use varying methodologies.

Second, recall that the population being studied were people who used marijuana fairly heavily for at least two years. Thus, even if the results of this study are true (a great rule of thumb is that one study alone never proves anything), the results would only strictly apply to people whose marijuana use is similar to those of this study. Not to mention that different marijuana strains can have wildly different effects, with different effects possible in different people.

Perhaps the theory laid out in the introduction (that predicts how the creativity of less heavy users of marijuana would change with marijuana use) could shed some light here, but this study also showed that the theory didn’t quite pan out as anticipated. This is not terribly surprising, since the authors seemed to base their hypothesis on one study[4] alone (or at least their text justifying their hypothesis relies heavily on this one study). The referenced study used eye blinking rates as a proxy for dopamine activity, which may not be entirely reliable.

The authors of the study offer a few other possibilities for why their hypothesis didn’t seem to hold in the study, beyond the possible unreliability of eye blink rates as a measure of dopamine activity. One possibility is that the high-dose group received too high of a dose, pushing them to the far right of the inverted U-shaped curve. A more fine-grained dosing study in the future could shed some light on this possibility. Alternatively, the authors noted that the high dose group experienced more negative effects than the other two groups. This led them to suggest that maybe the participants had to spend their cognitive resources dealing with the bad feelings rather than the task at hand, which fits with the “ego depletion” model of cognitive control.

As for why the placebo and low-dose groups performed equally in the AUT, the authors suggest several possibilities. One is that the dose was too low, since the participants were tolerant to THC and some[10] studies[11] have shown that higher doses are needed for the same effect in this population. Alternatively, the placebo may have contained other active ingredients or a minimal dose of THC that was necessary to induce an effect. Finally, perhaps the placebo effect was strong in the placebo group, since it was identical in smell and taste to marijuana with a higher THC level. This may have led to increased dopamine output simply based on expectation, which is an effect that has been noted in other[12] research[13].

The authors were less prolific in providing possible explanations as to why convergent thinking didn’t differ between any of the treatment groups. The main hypothesis they put forward is that they used a truncated, 14-question version of the RAT, which may not have been sensitive enough to measure differences accurately. Many possible factors weren’t discussed, such as the impacts of cannabinoids from marijuana on non-dopamine aspects of brain function, some of which may theoretically impact creativity.

The generalizability of this study is limited, both because it was done exclusively in people who used marijuana heavily, and because it only measured two aspects of creativity, both related to words on a written page. In addition, this study also generated a lot of possible hypotheses as to why the predictions of the authors didn’t pan out, many of which could be tested through further research.

The big picture

The current study somewhat clashes with a larger body of research on marijuana’s and THC’s effects on convergent and divergent thinking. The effects on divergent thinking tends to have more evidence surrounding it.

Early research[14] examining the effects of THC on divergent thinking found that low dose marijuana cigarettes (three milligrams of total THC) improved divergent thinking compared to higher doses (6 milligrams of THC). Later research[15] using oral THC noted increased verbal fluency in doses up to 15 milligrams. Long-term users of cannabis were tested in another study[16] which found that smoking marijuana improved divergent thinking, but only in those who assessed themselves to be not very creative in the first place. Another study found smoking marijuana improved aspects of divergent thinking only in long-term users, but not in people without a long history of exposure to cannabis. While all the previous studies found an improvement in divergent thinking, at least in some populations, one [17]study came up empty-handed.

Studies of marijuana’s effect on convergent thinking are fewer and far between, and both were mentioned above. One of the same studies[14] mentioned above found convergent thinking to be impaired by joints containing three or six milligrams of THC, compared to a control. Another later study[16] used the RAT and found that marijuana containing 10% THC may harm convergent thinking in people who rated themselves to be fairly creative.

While the conclusions that can be drawn from the body of research are not crystal-clear, it seems that the current study goes against what little evidence there is concerning marijuana’s effects on creativity, at least to some degree. Fortunately, contradictory and confusing research can serve as grist for the mill of scientists’ creativity in the future as they search for solutions.

Previous research done on marijuana’s and THC’s effects on convergent and divergent thinking tend to indicate that acute marijuana use can improve divergent thinking and harm convergent thinking. However, the evidence to date is limited and mixed.

Frequently Asked Questions

Q. How potent was the marijuana used in this study compared to that of average marijuana?

The THC content of most marijuana is between 5-10% THC[18], although THC content has been rising sharply in recent years, sometimes hitting the 30% mark. For comparison, the highest THC dose in this study was the equivalent of around 9% THC. However, the participants in this group had to inhale a large balloon full of the vapor, which required several hits.

Q. This study was done in long-term users of marijuana. What would the hypothesis be for how marijuana affects the creativity of people who don’t use it frequently?

By the reasoning laid out in the Introduction, marijuana use should make both divergent and convergent thinking worse. Recall that convergent thinking is inversely correlated with dopamine activity and divergent thinking has an upside-down “U” shaped correlation with respect to dopamine activity. This implies that any increase in dopamine activity will worsen convergent thinking, just like in people who use marijuana heavily over the long-term. However, since people who don’t use marijuana frequently will lie in the middle of the inverted “U” curve for divergent thinking, marijuana use on one occasion would push them to the far right of the curve, worsening their divergent thinking as well. This is different from the prediction the authors made for chronic cannabis users.

That’s the theory, anyway. As the study reveals, it didn’t quite pan out as expected.

Q. So the authors’ hypothesis was that marijuana’s effect on creativity is mediated by dopamine. Does this mean that other drugs that affect dopamine would in theory affect creative thinking?

Assuming the authors’ hypothesis is correct (which isn’t a great assumption, given the results of this study), this would indeed be the case. In fact, it’s somewhat odd that the authors of the current study didn’t take their hypothesis to its logical conclusion and mention other drugs in their discussion section.

There aren’t a whole lot of solid studies on other drugs’ effects on creativity. One study[19] on Adderall, which affects dopamine levels, found no effect on divergent thinking, and a positive effect on convergent thinking, but only in those who scored lower in convergent thinking to begin with; those with higher convergent thinking ability to start out with were either unaffected or impaired.

Q. Do other supplements affect creative thinking?

Remember that dopamine activity is related to creative thinking. Dopamine is synthesized from the amino acid tyrosine. So, in theory, it’s possible that tyrosine supplementation could affect creativity. One group recently put this hypothesis to the test[20] and indeed found that tyrosine improved convergent, but not divergent, thinking. While one study doesn’t prove anything, this is an interesting result. Hopefully, more research will be done in this area.

What should I know?

This study found that acute marijuana use in heavy users has no effect on one aspect of creativity called convergent thinking, which is the ability to unify disparate themes into a common thread. It also found that marijuana that contains high doses of THC may impair divergent thinking, which is the ability to brainstorm and come up with unique, loosely connected ideas. Marijuana containing lower doses of THC had no effect on divergent thinking. These results were somewhat unexpected based on past research.

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See other articles with similar topics: Cannabis, Cognition, THC.

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