Western University researchers suggest marijuana can have significant, long-term impacts on the adolescent brain.
The study saw adolescent rodents exposed to THC, or delta-9-tetrahydrocannabinol, the psychoactive component in marijuana. The adolescent rodents displayed substantial and persistent behavioural, neuronal, and molecular changes that are identical to neuropsychiatric conditions, such as schizophrenia.
“What was equally striking,” says researcher Professor Steven Laviolette, PhD (pictured), “was the fact that when we exposed the adult brain to the exact same levels of THC, these effects were completely absent.”
“Obviously not everyone who’s exposed to marijuana during their teenage years is going to develop any kind of problem. There seems to be a subset of individuals that have a certain genetic predisposition. What was, I think, one of the important messages in our findings was that we were able to link some of those genetic molecular pathways to what we know are risk factors in human populations as well.”
Lead author Justine Renard, PhD, says the research is critically important.
“With the current rise in adolescent cannabis use and the increasing THC content in newer cannabis strains, it is critically important to highlight the risk factors associated with exposure to marijuana, particularly during adolescence.”
Laviolette is hoping the research will lead to the development safer forms of medical marijuana.
Renard and Laviolette were supported in the study by a team of researchers at Schulich Medicine & Dentistry and the School’s Addiction Research Group.
The study found that adolescent rodents with THC exposure were socially withdrawn, anxious, cognitively disorganized, and had abnormal levels of dopamine; the changes continued into adulthood. Meantime, the adult rodents showed no harmful long-term effects though they did also experience changes to social cognition and memory.
The study can be viewed in its entirety in the journal Cerebral Cortex.