While studies in the past have suggested a connection between cannabis use in teenagers and brain development issues, a new study has found this not to be the case.
Ever since the “Reefer Madness” movie from the 1930s, claiming cannabis was the root of all evil, some research has suggested that cannabis use in teens can affect the development of the brain. However, new research carried out by Madeline Maier and her colleagues from Arizona State University, is suggesting that this claim isn’t true.
The research, published recently in the journal Drug and Alcohol Dependance closely tracked 200 teenagers with behavioral issues, living in Pittsburgh in the 1980s. These teens’ cannabis consumption rates were compared with brain scans taken in the past 20 years. According to the findings, there was no difference at all in brain structure.
As the authors of the research pointed out in the journal, “Even boys with the highest level of cannabis exposure in adolescence showed subcortical brain volumes and cortical brain volumes and thickness in adulthood that were similar to boys with almost no exposure to cannabis throughout adolescence.” In plain English, that means that cannabis use during teenage years did not affect the brain formation of these 200 subjects.
It must be noted that the study only looked at 200 subjects, all of them male. According to some, that’s not a substantial enough number. The other question is whether MRI scanning is the most effective way to track brain development in humans.
For Maier though, the most significant and vital part of the study was that cannabis use, even on young, developing brains, has no lasting or permanent effect. In Maier’s own words, “Reviews of these studies have revealed that, although a few studies have found evidence of an association between an earlier age-of-onset of cannabis use and adult brain structure, most studies have not.”
The subjects of the study were all boys aged 13-19 at the time they used cannabis. Something called “latent class growth analysis” was used to look at various trajectories. The subjects were put through structural neuroimaging when they were between the ages of 30–36. Fourteen a priori regions of interest in the brain were looked at. These included six subcortical and eight cortical regions.
Four different “cannabis trajectories” were examined – non-users/infrequent users, desisters, escalators, and chronic-relatively frequent users. However, when it came to the brain scans, these four categories showed no difference in terms of brain structure in “any subcortical or cortical region of interest.”
The conclusion of the study simply states: “Adolescent cannabis use is not associated with structural brain differences in adulthood.” Although this study may not be the most scientific, it does refute the age-old claim that cannabis use by teenagers affects the structure of their brain permanently. Other effects remain to be identified or ruled out.