The Athlete's Way

Sweat and the biology of bliss

Casual Marijuana Use Linked to Brain Changes in Young Adults

Marijuana is the most commonly used illicit drug in the United States. A study from April 2014 found that young adults who are light marijuana users—smoking pot once a week—have structural changes in the size and shape of two brain regions. This is the first study to show casual use of marijuana may be related to major brain changes. Read More

Size Matters

>> Of particular interest to the researchers was that the nucleus accumbens was abnormally large, and its alteration in size, shape and density was directly correlated to how many joints an individual had smoked.<<

Any control groups?
For the sake of argument: Is this good, bad or inconsequential is the question? Does size, "really," matter?

Size does matter if linked to loss of motivation, increased anxiety, and cognitive impairments.

Great column

You are to be commended for sontuing to educate young people as to the dangers inherent in consumption of cannabis. I myself was addicted to that substance for many years, and I can confirm how terrible a problem it is.

While under the influence of cannabis, I did and thought all kinds of stupid, pointless, destructive and even dangerius things.

It starts small, with listening to Pink Floyd while watching "The Wizard of Oz," but it always escalates. Soon, you start thinking that Bruce Springsteen's "Blinded By the Light" makes sense. Then you start thinking that Lou Reed could sing. Allen Ginsberg starts to seem like a genius. You get so hungry that you'll actually eat Circus Peanuts and say, "THese aren't bad at all." Then you find yourself thinking that "Big Bang Theory" is funny. Eventually, you may even convince yourself that having a dude's whangus in your rectum isn't such a gross idea at all.

It's just not worth it.

Super High Me

I am so fascinated by the cultural impact weed has generated. NBC did a poll on millenials and their perceptions about what is more dangerous or not. Unsurprisingly, weed was ranked less dangerous than tobacco, alcohol and sugar. Marijuana was considered more safer than sugar or alcohol. How this change in perception evolve throughout the decade is something I think needs to get looked at. Because the more you believe it is safe, the longer you will hold that conviction. And with more and more celebrities -- especially young celebrities-- endorsing the casual use of the drug, the drugs popularity will only get enhanced. Hollywood, too, is partly responsible.


Correlation does not equal causation. Correlation does not equal causation. Correlation does not equal causation.

How many times does this need to be stated?

When two variables, such as the size of the nucleus accumbens and marijuana use, are found to be related, one possiblity is that one variable caused the other. For example, marijuana use could affect the size of the NA. Alternatively, a larger-than-average nucleus acumbens could cause people to smoke marijuana.

The other possibility is that a third variable caused both. A particular genetic profile, for example, could produce both a large NA and an enjoyment of marijuana. Or both marijuana use and a large NA could be caused by environmental factors, or any one of an infinite number of other third variables. The problem with correlational research, unlike experiments, is that it is impossible to rule out ALL the third variables.

Christopher, this is not the first time that you've reported on correlational research and stated that it provides evidence of causation. It makes you sound silly.


This study has previously been proven as an ineffective, poorly designed study. The data was manipulated to distract from lack of significance. To small a sample size. The author should be held accountable for this degree of misinformation. It's just not that bad for you. Just try to keep it away from kids like we do most things... I still think sugar and acetaminophen are still much more dangerous..

Crap study with a crappy agenda

I posted a portion of this comment on another article that referenced this particular study..

Let's take a closer look at this and why this study and any other published work that includes references to it should be viewed with a great deal of scepticism. The marijuana study included a total of 40 people, yes I said 40 not 400 or 4000; with only 20 of those included being actual pot smokers age 18-25.

Dig a little deeper and you will find that the tolerances used to measure the amount of weed the 20 smokers in the study consumed daily was objective at best. Tolerances did not take into account any other drugs, alcohol or substances that the control group of 20 smokers used in addition to the marijuana. As shaky as these findings may be the National Institute on Drug Abuse has jumped on this as if it were earth shaking news to be viewed as a credible assessment of marijuana's impact on the developing human brain of people under the age of 26.

Only one media outlet embraced the study and gave it any attention at all, Fox News. They devoted 24 hours of editorial comment from each of their news anchors to supporting the study. Obviously they had to protect an agenda that would prevent marijuana from being legalized. They rake in a lot of revenue from the pharma, liquor and tobacco lobby, all would be hit hard if marijuana was legalized nationally.

Fair and Balanced

Thank you everyone for joining the discussion and sharing your thoughts on this hot-button topic.

I actually just Googled "Casual Use of Marijuana" to find that this research study has been covered by a wide range of media outlets since the report was published in The Journal of Neuroscience on April 16.

In writing this blog post I took into consideration different viewpoints and was very clear in my conclusion that more research on the casual use of cannabis is needed.

Also, to keep this blog post fair and balanced I included a direct link to 105 peer-reviewed studies on marijuana under the heading "Medical Marijuana Has Many Pros." In case anyone missed the link the first time they read my blog post here it is again:

Thank you again for joining the discussion and sharing your ideas with myself and other readers.

Christopher Bergland

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Christopher Bergland is a world-class endurance athlete, coach, author, and political activist.


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