Government Study Suggests Marijuana Changes Your Brain – in a Good Way


The U.S. government funded a study to examine ways marijuana use may alter a person’s brain and unwittingly showcased the plant’s value. The published results claim that marijuana changes critical parts of a user’s brain. Despite criticisms that the study’s methodologies and conclusions are flawed, the findings appear to support the idea that the world would be a better place if more people smoked pot.

The headlines this past week sensationally read “Even Casually Smoking Marijuana Can Change Your Brain”. The media is capitalizing on a study funded by the National Institute for Drug Abuse (NIDA) that imaged parts of the brain of 20 young marijuana smokers and compared those results to a sample of non-smokers. The fMRI results looked for differences in the amygdala and nucleus accumbens between the two groups. The researchers found users’ had denser gray matter in their nucleus accumbens and larger amygdalae compared to the control group.

According to Fox News the co-senior author of the study, Dr. Hans Breitner announced “the amygdala had abnormalities for shape and density, and only volume correlated with use [of marijuana]… the changes were greater with the amount of marijuana used.”

The areas of the brain picked for the study are associated with emotional processing, decision making and motivation. Specifically the nucleus accumbens is the part of the brain that plays an important role in pleasure as well as fear, aggression, impulsivity and addiction. The amygdala is responsible for processing memory, decision making, and handling emotions.

Critiques of how the study was performed and the conclusions it reached have been equally numerous. (Examples are here and here) The list of observations circulating the internet as of today (4/20/2014) can be summarized as:

  • Correlation does not equal causation.
    For instance, it is possible that the marijuana smokers already had variations in their nucleus accumbens – which could actually cause them to be predisposed to ingest more marijuana, drink more alcohol, smoke more tobacco and use other drugs for a dopamine boost. Use of all of these substances ranked significantly higher in the marijuana users compared to the control group.
  • The study used an unusually small sample size.
    Only 20 marijuana users were compared to 20 control group members. The findings represent a very small data point.
  • The marijuana group is not composed of “casual” users.
    On average each participant smoked marijuana 3.8 days each week and 1.8 joints per smoking occasion. This rate is near the “heavy” end of use. Also consider that participants were also asked to remember and estimate their use over the previous 90 days leading up to the study. This way of studying use introduces the potential for large errors. Detailed daily data collection would have been a more reliable way of documenting the usage rate.
  • The research did not actually study changes in the brain.
    There were no pre-marijuana magnetic resonance images taken. To actually measure changes, fMRIs would have to be performed on everyone in the marijuana user group before they took the first toke of their lives.  This study did not study changes, but merely compared different brain images and assumed variations were caused by marijuana. To conclude that marijuana “changed” the brain requires a biased leap of faith.
  • Variations in gray matter densities of nucleus accumbens are relatively unstudied.
    Previous studies revealing how abnormal nucleus accumbens affect behavior focus on how the presence of lesions (not size or density) correlates to addiction.
  • NIDA studies are inherently biased.
    Only studies that point to negative effects of drugs are accepted by NIDA. This particular study is designed to seek problems and is not objective.
  • The study found an increase in gray matter in the nucleus accumbens and amygdalae. Typically more gray matter is considered a good thing.

Despite taking issue with how the study was conducted or the legitimacy of the dangers it alludes to, most marijuana enthusiasts would agree that the plant, when ingested, does have an impact on the aspects of consciousness referenced in the study (emotional processing, decision making, and motivation). But in what ways?

Rather than repeating stereotypes or telling personal anecdotes, let’s look at the results of the first federally funded research that studied the common psychological impacts of marijuana ingestion. The 300+ page study, published under the somewhat dated title of On Being Stoned, surveyed users about their experiences from using marijuana.

The following is a list of all the common traits experienced during a marijuana high (of varying intensities) as reported in On Being Stoned in the same areas studied by Dr. Breitner:

Emotional Processing

  • Feel good, mild euphoria (occurs at “fairly” stoned level)
  • Learn a lot about psychological processes (“fairly” stoned)
  • Feel more open to experience (“fair to strongly” stoned)
  • Close mental contact with partner when making love (“fair to strongly” stoned)
  • Empathize strongly with others (“fair to strongly” stoned)
  • Mood before marijuana use amplified (“fair to strongly” stoned)
  • Group takes on a sense of unity (“fair to strongly” stoned)
  • Deep insights into others (“strongly” stoned)
  • Feel emotions more strongly (“strongly” stoned)
  • More aware of bodily components of emotion (“strongly” stoned)
  • Lose sense of separate self, at one with the world (“very strongly” stoned)


Decision Making

  • Easier to accept what happens, less need for control (occurs at “fairly” stoned level)
  • Feel as if mind is working more efficiently (“Fair to strongly” stoned)
  • Work on tasks less accurately, judged by later evaluation (“Fair to strongly” stoned)
  • Skip intermediate steps in problem solving (“Strongly” stoned)
  • More here-and-now, deeply in present moment (“strongly” stoned)
  • Can’t think clearly, thoughts slip away before grasped (“very strongly” stoned)



  • Easier to accept what happens, less need for control (occurs at “fairly” stoned level)
  • Work at tasks with extra energy and absorption (“fairly” stoned)
  • Physically relaxed (“fair to strongly” stoned)
  • More involved in ordinary tasks (“fair to strongly” stoned)
  • Feel capable and powerful (“strongly” stoned)

A review of these psychological changes associated with marijuana use reveals a list of traits that, for the most part, we should all embrace and strive to cultivate as a society. Aside from short-term memory problems associated with the highest levels of marijuana intoxication, these side-effects should, if anything, encourage people to smoke more pot mindfully.

Going back to the NIDA study, the senior author notes a direct correlation between amount of marijuana use and amygdala size. Fortunately for marijuana users, this finding bodes well and corroborates the benevolent tendencies revealed in Tart’s research – marijuana smokers tend to be more benevolent, empathetic and understand their social role in a global context. Numerous studies on how larger amygdalae affect behavior show consistent results:

  • Previous amygdala research has shown that enlargement in the normal population might be related to creative mental activity.
  • Amygdalae volume correlates positively with both the size and complexity of social networks according to this study.
  • Individuals with larger amygdalae are better able to make accurate social judgments about other person’s faces. (source)
  • Larger amygdalae allow for greater emotional intelligence, enabling greater societal integration and cooperation with others. (source)
  • Bipolar patients tend to have considerably smaller amygdalae volumes. (source)

Also consider the recent data from Colorado that shows violent crime is down since marijuana’s legalization. If, as the NIDA-funded research suggests, marijuana does indeed increase amygdala size, previous studies show this to be a highly desirable outcome. If given the choice, we should ask for bigger amygdalae. Despite the flaws in this recent research, the conclusions suggest humans as a whole are better off with the plant.

But if you are intimately familiar with marijuana, you already knew that.
Let us declare nature to be legitimate. All plants should be declared legal, and all animals for that matter. The notion of illegal plants and animals is obnoxious and ridiculous.  ~Terence McKenna

The study in discussion has since been superseded with a more comprehensive study published in January 2015.

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