Marijuana Linked to Schizophrenic-Related Brain Changes


Marijuana PlantsMarijuana use may cause poor memory and abnormal changes in brain function that resemble the changes found in individuals with schizophrenia, says a new study published in the journal Schizophrenia Bulletin.

Previous research on the effects of marijuana have found that the drug causes myriad long and short term health effects. Although a recent study discovered that delta-9-tetrahydrocannabinol, a mind-altering chemical found in marijuana more called THC, could help treat individuals autoimmune disorders, marijuana use most commonly affects the heart and mental health of users.

With the brain-altering affects of the drug in mind, researchers from the Feinburg School of Medicine at Northwestern University in Illinois recently studied a group of regular marijuana users in their early 20s. The researchers hoped to clarify the relationship between marijuana use and working memory (WM) impairments. Working memory affects everyday functioning and academic performance.

All of the participants in the study had begun using marijuana at 16 or 17 years of age and had smoked daily for approximately three years but had been drug-free for 2two years prior to the study. None of the participants had a history of other drug abuse.

The participants in the study were compared to a group of healthy controls, subjects with a marijuana use disorder, participants with schizophrenia with no history of substance use disorders, and schizophrenia subjects with a marijuana use disorder. In total, the study looked at a total of 97 individuals.


As the researchers discovered, the participants who had begun using marijuana at 16 or 17 years of age exhibited deterioration in the thalamus, the area of the brain that is important for learning, memory, and communication. This group of participants also exhibited abnormal changes in the brain, changes which are linked to problems with working memory. Despite not using marijuana for two years prior to the study, this group of participants still exhibited abnormal brain structures that affected memory and brain function.

Additionally, the researchers discovered that the brain deterioration found in the participants who had begun using marijuana at 16 or 17 years of age resembles the brain deterioration found in schizophrenic patients who used marijuana.

In other words, in addition to long term changes in brain function, marijuana use also contributes to changes in brain structure that is associated with the mental disorder schizophrenia. Furthermore, individuals with a family history of schizophrenia may increase their risk of developing the disease by using marijuana.

John Csernansky, co-senior study author from the Northwestern University Feinburg School of Medicine and Northwestern Memorial Hospital, comments on the recent findings:

“The abuse of popular street drugs, such as marijuana, may have dangerous implications for young people who are developing or have developed mental disorders.

“This paper is among the first to reveal that the use of marijuana may contribute to the changes in brain structure that have been associated with having schizophrenia.”

The results of this study indicate that marijuana use causes long term, and often detrimental, effects on the brain such as schizophrenic-related brain changes. Further studies need to be conducted to fully understand the full effects of the drug.


Cannabis-Related Working Memory Deficits and Associated Subcortical Morphological Differences in Healthy Individuals and Schizophrenia Subjects:
Marijuana use linked to schizophrenic-related brain changes:

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Written by Heather Johnson

Heather is a writer, librarian, linguist, wife, and mother who loves her husband, children, dogs, and cats. She has a bachelor's degree in English with a minor in creative writing and master's degrees in library and information science and English studies with a concentration in linguistics.

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