The theory that marijuana use can negatively—and potentially permanently—rewire the brain up until a person reaches the age of 25 is based on misleading science that neglects to account for key factors in cognitive maturity, according to a new research paper.
The study, published on Monday in the American Journal on Drug and Alcohol Abuse, examined the scientific literature around neurodevelopment. While most U.S. states prevent people under 21 to access adult-use cannabis products, some public health advocates are pushing to the legal age limit to 25.
But the researchers, who are affiliated with the advocacy group Doctors for Drug Policy Reform, concluded that those proposals would not meaningfully prevent adverse mental health outcomes for consumers.
“Invoking age 25 as a bright line for brain maturity is not supported by neuroscience,” they wrote. “Cannabis policy should reflect evidence and fairness, not mythology.”
The paper states that there’s “no empirically defined neurodevelopmental endpoint at age 25,” as brain maturation “is a nonlinear process, region-specific, influenced by sex and specific physiological processes.”
“Importantly, existing evidence does not demonstrate greater long-term cognitive or neurophysiological harm attributable to cannabis use in individuals aged 18-25 years compared to those older than 25,” it says.
The researchers reviewed data on the macrostructural and microstructural development of the brain, which shows that such maturation is “mostly complete by the end of adolescence, around age 18.”
“Other, more subtle developmental changes continue throughout the third decade of life. The often-cited claim that brain development ‘ends’ at 25 is not clearly supported by primary neuroscientific literature,” it says.
Hellbound and Down 