Why Are Cannabis Users Susceptible to Memory Distortion?

Chronic marijuana use can make imaginary memories seem like reality.

Posted Apr 28, 2015

M.C. Escher/Creative Commons
Source: M.C. Escher/Creative Commons

A new study published in Molecular Psychiatry reports that chronic cannabis users are more likely to experience false memories. We're all susceptible to false memories and distorted perceptions of reality, but excessive marijuana use appears to compromise the ability to differentiate between true and false memories.

Another recent study found that in the world of visual perception and motor functioning that the brain creates two different maps of your environment—an illusion-prone map used for creating conscious perceptions of the world, and an illusion-resistant map used for guiding movements. 

Chronic Cannabis Users are More Susceptible to False Memories

The cannabis study was conducted in Spain by a coalition of researchers. The April 2015 study titled, "Telling True from False: Cannabis Users Show Increased Susceptibility to False Memories," was published in the journal Molecular Psychiatry.

One of the most common side effects of smoking too much marijuana is that it creates memory problems. Statistically, chronic users of cannabis have more difficulty than the general population consolidating new memories and retrieving old memories.

The new Spanish study found that chronic use of marijuana increases the odds that imaginary or false memories will appear real. These findings should come as no surprise. In many ways, the whole point of getting high is usually to alter one's perceptions of reality.

Do you smoke marijuana? I stopped using cannabis or doing any drugs after I had a classic "bad trip" on psychedelic mushrooms as a teenager. Have you ever had a bad trip? I described the harrowing effect that psilocybin had on my mind in The Athlete's Way by saying,

I don’t know if you’ve ever had a bad trip, but it feels like all the tumblers in your brain are turning and reconfiguring—unlocking doors of perception that should stay shut, closing windows that should stay open—all the while re-etching the blueprints of your psyche and the foundation of your soul ... fusing your synapses into new configurations and permanently rearranging the architecture of your mind.

Having a bad trip made the world seem like a surreal Escher lithograph in a nightmarish way. I had to stop doing any type of drugs after I had that bad trip because even one hit of pot gives me flashbacks to how dramatically drugs can distort reality. The thought of being really high on drugs remains terrifying to me. 

Neuroscientists Discover That Dual Illusions Can Create an Alternative Reality

"Rotating Snakes" by Akiyoshi Kitaoka/Wikimedia
Source: "Rotating Snakes" by Akiyoshi Kitaoka/Wikimedia

Another April 2015 study about altered perceptions titled, “The Two-Wrongs Model Explains Perception-Action Dissociations for Illusions Driven by Distortions of the Egocentric Reference Frame," was published in Frontiers in Human Neuroscience

For this study, researchers at the University of Oregon presented participants with an optical illusion that made all the angles of doors and windows in a room off-kilter. Then they observed how the brain tried to reconfigure a new reality out of the disorienting landscape that made sense.

The human brain is designed to reshape reality to fit certain rules of perspective. This can lead to the creation of false memories based on optical illusions. Memory is a malleable process that is created progressively like a tapestry that is always having new threads woven into the scene. Any memory, true or false, is subject to distortions over time.

Lead author of the study, Paul Dassonville, professor of psychology and member of the Institute of Neuroscience, described his research in a press release saying,

In the lab, we explore the kinds of assumptions the brain makes about the world around us. In the real world, judgments about an object's orientation are aided by visual clues that help anchor the perception of vertical, such as the view of a doorframe, a window frame or where two walls meet. In the laboratory, these cues were replaced by misleading cues of the tilted frame, resulting in the illusion.

The perceptual illusion caused by our tilted frame is analogous to a treasure map that is created using the faulty compass. The map is technically incorrect, but as long as you use the combination of the faulty map and the faulty compass to navigate around, you'll be able to accurately find the treasure once again because the errors cancel out.

In the experimental task, the cancellation of errors allowed the subjects to make accurate movements in spite of the illusion. Could it be that some of the false memories created through chronic cannabis use stem from the same effect?

The findings from this study challenge the traditional model of visual function which suggests that conscious perception of an object's location is formed in a wholly different part of the brain than the area used to guide actions.

Conclusion: Chronic Use of Marijuana May Worsen Age-Related Memory Loss

The latest cannabis research suggests that heavy marijuana users are susceptible to memory distortions, even weeks after not consuming the drug. The chronic use of cannabis has prolonged effects on brain mechanisms that can make it impossible for someone to differentiate between real and imaginary events. 

Recently, I went to see the movie Still Alice in which Julianne Moore plays a woman with early onset Alzheimer's. Although the movie has nothing to do with smoking cannabis, it captured how tragic memory loss is for both the individual and his or her family. Personally, the movie inspired me to do everything in my power to make daily lifestyle choices that will preserve my memory well into the future. 

If you're a heavy marijuana smoker, you might want to consider smoking less in order to preserve your true memories. From a clinical viewpoint, the results of this study reaffirm that chronic use of cannabis can worsen problems with age-related memory loss. If you like to smoke weed, remember that the latest research shows moderation is key for maintaining your long-term brain health and cognitive function.

If you'd like to read more on this topic, check out my Psychology Today blog posts: 

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