Study Shows Alcohol Impacts Cortical Thickness in Young Adults, Cannabis Does Not

A new study refutes what many claim is a danger of legal cannabis, as the findings showed that, while alcohol can have an impact on cortical thickness in younger users, cannabis does not. 

The study, titled “The effects of alcohol and cannabis use on the cortical thickness of cognitive control and salience brain networks in emerging adulthood: A co-twin control study,” was published in the journal Biological Psychiatry and conducted by researchers at the University of Minnesota.

These researchers looked at the relationship between alcohol and cannabis exposure when it comes to the brain morphology of young adults. It considered a population-based sample of 436 twins, all 24 years old. By looking at frequency, density, quantity, and level of intoxication from both alcohol and cannabis, the researchers were able to gather data about how cannabis impacts cortical thickness. The cortical consistency was measured using magnetic resonance imaging. 

When conducting this research, the team kept in mind that other studies often assume that even casual substance exposure can have an impact on brain structure. However, until now, this was a largely untested theory, and one that does not take other factors like familiar risk into account. By studying the twins who were using alcohol and cannabis, the study was able to directly measure how the two different substances can affect people.

The study explained,  “Greater alcohol, but not cannabis, misuse was associated with reduced thickness of prefrontal and frontal medial cortices, as well as [the] temporal lobe, intraparietal sulcus, insula, parietal operculum, precuneus, and parietal medial areas.”

Why These Findings Matter

The reason this research is so important is that intellectual ability is thought to be related to brain structure, including how thick the cerebral cortex is. Thus, it is very important to understand how substances and other impacts can change that thickness. But, in the case of cannabis, it seems the thickness wasn’t changed much.

“No significant associations between cannabis use and thickness were observed,” the study concluded. This study provides novel evidence that alcohol-related reductions in cortical thickness of control/salience brain networks likely represent the effects of alcohol exposure and premorbid characteristics of the genetic predisposition to misuse alcohol. The dual effects of these two alcohol-related causal influences have important and complementary implications regarding public health and prevention efforts to curb youth drinking.”

This is consistent with the findings of other studies, literature reviews, and papers, most of which claim that any damage done is probably from alcohol, not from cannabis. A literature review of many studies posted in JAMA Psychiatry explains that, “Associations between cannabis use and cognitive functioning in cross-sectional studies of adolescents and young adults are small and may be of questionable clinical importance for most individuals. Furthermore, abstinence of longer than 72 hours diminishes cognitive deficits associated with cannabis use. Results indicate that previous studies of cannabis youth may have overstated the magnitude and persistence of cognitive deficits associated with marijuana use.”

As the world opens up for more research about cannabis to be done, no doubt more misconceptions will be dispelled.