The system of the brain responsible for mediating the effects of cannabis, the endocannabinoid system, is most vulnerable to the drug during adolescence, according to new research.
"During adolescence the endocannabinoid system in the brain undergoes a lot of change, and interfering with these changes by using cannabis could have consequences for the development of healthy brains in adults," says Dr Leonora Long of Neuroscience Research Australia (NeuRA).
Dr Leonora Long and colleagues studied how the endocannabinoid system changes over the course of a lifetime and found that most change occurs in the adolescent brain, a significant period of developmental change.
"Considering that cannabis use is common amongst teens and that adolescence is a time when adult behaviours and decision-making are being developed, our discovery that the adolescent brain may be more vulnerable to the effects of cannabis is significant," says Dr Long.
The endocannabinoid system is involved in appetite, pain-sensation, mood and memory, and affects the way neurons in the brain communicate with each other. Cannabis causes problems by attaching to proteins in the endocannabinoid system and interfering with this communication role.
"Disrupting endocannabinoid signalling through exposure to cannabis is likely to have a higher impact if the exposure happens at a time of change and when achieving balance in communication between neurons is very important, such as during adolescence," says Dr Long.
How was this study conducted?
- A cohort of postmortem human brain tissue from babies 39 days old to adults 45 years old was used.
- Homogenate tissue and brain slices were examined to look for the anatomical distribution of components of the endocannabinoid system.
- The researchers used microarray with qPCR validation and in situ hybridisation to quantify mRNA for the central endocannabinoid receptor CB1R, endocannabinoid synthetic enzymes (DAGLα and NAPE-PLD), and inactivating enzymes (MGL, ABHD6 and FAAH).