Adult Marijuana and “Brain Damage”

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By Guest Author John Soltys

The Museum’s Health Sciences Department is partnering with the University of Colorado Anschutz Medical Campus to publish a monthly series on the Museum blog called “Know Health”. The articles focus on current health topics selected by CU’s medical and graduate students in order to provide both English and Spanish speaking communities with current, accurate information. The posts in the “Know Health” series are edited versions of articles that first appeared in Contrapoder magazine. Thank you to the students at the University of Colorado Anschutz Medical Campus for bringing these stories to life.



(aka Dr. Nicole Garneau, chair and curator, Health Sciences Department)


Cannabis _Adobe Stock _65754217


Adult Marijuana and “Brain Damage”

Guest Author, John Soltys

Student at the School of Medicine at the University of Colorado Anschutz Medical Campus



[en Español]


Major policy changes regarding marijuana use are being entertained worldwide. Taking center stage are debates surrounding both recreational and medicinal benefits, given the popular opinion that marijuana is a safer drug than most. So does marijuana really cause brain damage? Discerning fact from fiction is important in making educated choices about marijuana use. Here, the impact of marijuana on the adult brain is explored, but check out our previous article to understand how marijuana changes the brain of children and teenagers.

The idea that marijuana may be safe arises from two major findings. First, many drugs including cocaine, methamphetamine and ecstasy all produce immediate changes in brain structure and function that are seen with brain-imaging techniques that doctors commonly use. Marijuana is popularly perceived as “safe” because marijuana does not cause these changes.

However, although these images are powerful they may not tell the complete story. A common symptom of marijuana use is short-term memory loss. This occurs because marijuana weakens the ability of memory cells to form new memories. Researchers have used alternate advanced imaging and laboratory techniques to show that this memory loss indeed results from a change in brain cell structure. These techniques require a great deal of time and can only see a small part of the brain, so it remains unclear if these changes are temporary or permanent and how much of the brain is changed. It is clear, however, that this change in brain cell structure does occur.

The second major finding arises from the discovery of what scientists call the endocannabinoid system. Endocannabinoids are small molecules found throughout your body. In healthy adults, endocannabinoids have positive effects on brain cells and promote the survival and normal function of these cells. Your body transforms marijuana into dozens of other compounds that act like, or mimic, endocannabinoids and therefore may produce the same beneficial effects. This means that marijuana may actually promote brain cell function and has led to the idea that medical marijuana may be useful in treating anxiety and other brain disorders.

There is an important caveat to this idea. In many disorders where medical marijuana may be beneficial, there is already a documented loss of brain function. The endocannabinoids that should be present and promote brain cell survival may be lost, and marijuana may replace these missing compounds. In a healthy brain, however, the endocannabinoids are functioning normally. Adding more may be “too much of a good thing” and paradoxically cause brain cell damage. It is unclear what healthy endocannabinoid levels are, but it is clear that different levels have different effects on the brain.

So what’s the verdict? Recent research has documented that marijuana indeed causes changes in brain structure and function albeit to an unknown extent. No drug is completely safe, and marijuana may not be an exception.


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