It has long been the received wisdom that cannabis use in adolescence can damage brain function in teenagers who choose to use. But the latest science due for publication next month is set to disprove that belief altogether. It follows recently released research which appeared to dismiss a link between cannabis and lower IQ.
A study conducted by researchers at Arizona State University has found that adolescent cannabis use may not pose much long-term risk on brain function at all. Next month’s issue of Drug and Alcohol Dependence, the international original research journal published by Elsevier will contain that latest science.
Evidence has four-decade timeline
Entitled, ‘Tested associations between prospectively-assessed trajectories of adolescent cannabis use and adult brain structure in a sample of boys followed to adulthood,' the authors of the report detailed the process for their study. Researchers analysed self-reported cannabis use among boys aged 13-19 in Pittsburgh in the year 1980. The 1000 boys examined were then categorized in the following four ‘adolescent cannabis trajectories':
- Non-users/infrequent users
- Chronic-relatively frequent users
After a thorough analysis over the years, the researchers noted –“boys in different trajectory groups did not differ in terms of adult brain structure in any subcortical or cortical region of interest”. Furthermore, a subset of 181 of the boys subsequently underwent structural neuroimaging in adulthood when they were between ages 30-36. That subset was then tested to identify any differences in adult brain structure.
The researchers inferred that adolescent cannabis use had no link with structural brain differences in adulthood. “Even boys with the highest level of marijuana consumption rate in adolescence showed subcortical brain volumes and cortical brain volumes and thickness in adulthood that were in line to those of boys with almost no exposure to marijuana throughout adolescence.”
What is particularly exciting from a cannabis advocacy perspective is that the research meets the criterion of demonstrating long-term effects. With many governments continually arguing that more long-term research into the effects of cannabis needs to be done before laws are relaxed, this looks to be yet another important body of evidence.