Marijuana use can damage brain development and structure, study shows


The legalization of marijuana has led to the greater acceptance and availability of cannabis products, which has contributed to increased marijuana use among young people. Despite the lack of knowledge that exists about the consequences of higher potency cannabis strains and its’ long-term use, there seems to be a widespread misconception that marijuana use is safe.

Although many people, especially youth, are viewing marijuana as less harmful, researchers contend that marijuana use has damaging consequences on the development and structure of the brain, especially among youth whose brains are still in development. Smoking high-potency cannabis strains can significantly damage the corpus callosum, a white-matter structure in the brain that connects and allows communication between the left and right cerebral hemispheres, according to recent research published in the journal Psychological Medicine.

The first study of its kind, Silvia Rigucci, M.D., and her colleagues examined the effect of cannabis strains containing higher concentrations of delta-9-tetrahydrocannabinol (THC) and frequency of cannabis use on the structure of the brain. Using a magnetic resonance imaging (MRI) technique that produced three-dimensional images of white matter volume in the corpus callosum, the researchers examined the structural brain differences in the corpus callosum, an area of the brain densely packed with cannabinoid receptors that are targeted by THC.

The participants included 56 patients with first-episode psychosis (FEP) (37 were cannabis users) and 43 controls without psychosis (22 were cannabis users). The researchers found that users of high-potency cannabis exhibited greater white matter damage compared to both low-potency users and those who had never used cannabis. In addition, participants who used cannabis on a daily basis exhibited greater white matter damage in the corpus callosum compared to occasional users and those who had never used.

The results of this study indicate that high-potency cannabis and frequent cannabis use can damage the microstructural organization in the corpus callosum in individuals with and without psychosis. Earlier neuroimaging studies suggest that regular cannabis use can also contribute to significantly reduced gray matter volume in areas of the brain with a high density of cannabinoid CB1 receptors (e.g., the medial temporal cortex, temporal pole, parahippocampal gyrus, left insula and orbitofrontal cortex).

The link between cannabis use and psychotic disorders

Previous studies have found that users of high-potency cannabis have three times the risk of psychotic disorders compared to those who do not use cannabis. High doses of marijuana can also induce brief psychotic reactions in people without schizophrenia or another psychotic disorder and contribute to an earlier onset of psychotic symptoms.

Cannabis use can contribute to the development of psychotic disorders such as schizophrenia, although this risk varies considerably depending on the amount and frequency of cannabis use and the age at which an individual first smokes marijuana. Studies suggest that psychotic disorders are more likely to develop in adulthood among adolescents who use marijuana, primarily if they are genetically vulnerable.

High-potency cannabis use during adolescence

Many believe that marijuana use is safe since it is sold and consumed for medicinal purposes. As a result, more and more young people are reporting using marijuana on a daily basis, which can have damaging consequences on the structure and development of important areas of the brain.

Rigucci and her colleagues’ findings suggest that the high-potency cannabis strains that have become available since marijuana’s legalization can be dangerous and may lead to damage to significant areas of the brain. These findings support those of earlier studies, which have found that heavy marijuana use during adolescence alters the development of gray and white matter in the brain.

Despite the widespread view of marijuana as being harmless, recent research has determined that this is not the case. Marijuana use, especially among young people, can have detrimental consequences on adolescents’ brain development and structure. Furthermore, the availability of higher potency cannabis strains increases youth’s risks for marijuana abuse and dependence. White River Academy is a therapeutic treatment facility for boys between the ages of 12 and 17 with emotional and behavioral problems. For more information about marijuana abuse or about White River Academy, please contact our 24/7 helpline to speak to a member of our team.

About the author

Amanda Habermann, graduated from California Lutheran University, she received her M.S. in clinical psychology with an emphasis in psychiatric rehabilitation. She brings to the team her background in research, testing and assessment, diagnosis and recovery techniques. 

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