Teen marijuana use: Just 1 to 2 joints may affect brain development
Published Wednesday, January 16, 2019 8:46PM EST
A new study suggests that even small amounts of teenage cannabis use – just one or two joints before the age of 15 – may be associated with significant changes in brain development.
The research, published in the Journal of Neuroscience, looked at 46 teens aged 14 or younger who had smoked the equivalent of one to two joints in their lifetimes. Their brain scans were compared to those of 46 kids who had never used marijuana but were of the same in terms of age, IQ, socio-economic statuses, experience with alcohol and past nicotine use.
“Kids who reported just one or two (cannabis) uses in their lifetimes actually showed increased grey matter volumes in a whole bunch of brain regions,” said the study’s lead author, psychiatrist Hugh Garavan of the University of Vermont.
Garavan told CTV News Channel on Wednesday that he believes it’s possible that the larger brain volumes in those who used marijuana could be the result of less synaptic pruning, which is the process whereby the brain cells needed to soak up information in childhood are killed off in the teenage years to create a more efficient brain.
Research in animals had previously suggested a link between cannabis and brain volume but Garavan says he was nonetheless surprised.
“What made this interesting was that the brain regions affected were those areas where cannabis tends to have its effects on the brain,” he said.
The regions seemingly affected were the hippocampus, which is involved in memory formation and spatial abilities, and the amygdala, which is involved in fear and threat processing.
Garavan said that the study should be interpreted with caution, but added that the “pattern seen tends to be associated with lower IQs ... and anxiety.”
The 2017 Ontario Student Drug Use and Health Survey asked 11,435 students in grades 7 to 12 about their drug use. Nearly one in 10 ninth graders and one in five tenth graders reported having used cannabis in the past year.
Health Canada offers the following tips for parents to help prevent drug use in teens.
- Be aware of the many changes that your teen is going through. These changes may make teens feel extremely stressed, less confident, vulnerable and depressed.
- Be sympathetic to what it must be like for your teen to be experiencing such feelings. Remember a time when you went through many changes and how that felt.
- Although they may want to be more independent, your teen needs structure and support. Your support matters.
- Always communicate a reason for your decisions. When you have to say no, make sure you explain why. Share your standards of conduct and achievement.
- Establish regular household events, set limits, monitor homework, attend parent-teacher conferences and more.
- Show ongoing interest in your teen’s life and respect them. Take the time to listen to your teen. Although it may often seem that having a conversation with you is at the bottom of their to do list - find the teachable moments where you can talk openly together. Teachable moments can happen while driving in the car, at the dinner table while discussing a situation at school or a current event in the news.