JAN 16, 2019 10:40 AM PST

Effects of Low Cannabis Use in Teens on the Brain

WRITTEN BY: Amy Loriaux

A recent article published in the Journal of Neuroscience presents more data to suggest that marijuana use in adolescents is harmful to brain development at this stage of life. This particular study focused on teens who have smoked very little marijuana. While most studies have looked at neural correlates related to heavy use in teenagers, this study focused on kids who have just smoked as little as once or twice at the age of 14. Results found increases in grey matter (where the cell bodies of neurons live) in this population, especially in the amygdala and the hippocampus.

MRI image illustrating grey and white matter. Source: Pixabay.com

This study, published by Drs. Hugh Garavan, Ph.D. and Catherine Orr, Ph.D., from the Larner College of Medicine at the University of Vermont, adds to the cumulative body of work showing that cannabis use among teenagers poses a severe risk to adolescent brain development. These changes also seem to correlate with issues such as problems in school performance; higher likelihoods to develop depression; and increased risk for cigarette use.

Several pieces of evidence show that heavy early cannabis use in adolescents can have detrimental effects on the brain. Teen marijuana users generally had worse scores on memory and attention tasks compared to controls. They also had more hippocampal activation during the completion of these tests. These results were interpreted as a failure of inhibitory neurons to calm down hippocampal activity in order for it to perform at its optimal level. Furthermore, measurements of cerebral blood flow (a proxy for neuronal activity) was decreased across several brain regions in teens who were heavy marijuana users compared to controls. Fortunately, four weeks of abstinence corrected these deficits in cerebral blood flow.

Source: Pixabay.com

What is interesting about the current study is that the brains of young teens were found to already differentiate from controls after only using once or twice at age 14. This is the first study looking at whether low use of marijuana still alters adolescent brains. The findings point to developmental deficits due to low cannabis use. According to Dr. Garavan, "You're changing your brain with just one or two joints. Most people would likely assume that one or two joints would have no impact on the brain." The reason for the increase in grey matter is unclear, but it could be related to the process of "pruning" that is still occurring in teenagers.

Pruning is a very important process in neurodevelopment. It is a process by which unnecessary neuronal connections are removed, or "pruned" during the development into a full adult brain. This process occurs mainly during infancy, and deficiencies of the pruning process at this age have been proposed as a mechanism for autism. This is not to say that marijuana use will make young users autistic, but it does highlight the sensitivity of our brains during our teenage years to cannabis. 

Check out this video that wonderfully illustrates the effects of cannabis on the developing teen brain.

Sources: Journal of Neuroscience, AddictionAnnals of the New York Academy of Sciences, Psychopharmacology, ScienceDaily.com, Mental Health Weekly Digest 

About the Author
  • I currently work at a small CRO involved in clinical trial management.
You May Also Like
MAY 04, 2021
Health & Medicine
Detecting Driving Impairment From Cannabis Use Is Extremely Tricky, Experts Say
MAY 04, 2021
Detecting Driving Impairment From Cannabis Use Is Extremely Tricky, Experts Say
Don’t drive high is a sensible message, but ultimately nobody really knows the impact of cannabis on an individual ...
MAY 25, 2021
Health & Medicine
Cannabis: Could it Help Chronic Itch?
MAY 25, 2021
Cannabis: Could it Help Chronic Itch?
Chronic itch —clinically known as chronic pruritus — is characterized as an unrelenting sensation to scratch ...
JUN 02, 2021
Cannabis Sciences
Can CBD Help Manage Symptoms of Diabetes?
JUN 02, 2021
Can CBD Help Manage Symptoms of Diabetes?
As cannabidiol (CBD) products become increasingly mainstream, more people are using them to manage symptoms for chronic ...
JUN 04, 2021
Cannabis Sciences
Neurotechnology and Saliva Tests Detect Psychoactive Effects of Cannabis
JUN 04, 2021
Neurotechnology and Saliva Tests Detect Psychoactive Effects of Cannabis
Researchers from contract research organization, KGK Science, working on behalf of neurotechnology firm Zentrela, have f ...
JUL 01, 2021
Health & Medicine
Cannabis Can Ease Symptoms in Women WIth Gynecological Cancers
JUL 01, 2021
Cannabis Can Ease Symptoms in Women WIth Gynecological Cancers
A small study has shown that cannabis can help reduce unpleasant symptoms in women with gynecological cancers. The five ...
AUG 11, 2021
Health & Medicine
Cannabis Users Are Normal Hardworking Members of the Community Too
AUG 11, 2021
Cannabis Users Are Normal Hardworking Members of the Community Too
  Who is the typical cannabis user? There are many stereotypes and misconception about weed use, most of them not f ...
Loading Comments...