Last updated : April 21, 2025
The news is alarming—in light of the Rocky Mountain High Intensity Drug Trafficking Area’s (RMHIDTA) 2015 report on the impact of marijuana legalization in Colorado, the American College of Pediatricians (ACPEDS) has updated its recommendations on marijuana use by adolescents and come down squarely against legalization. Among the ACPED’s most disturbing concerns is growing scientific evidence that pot triggers irreversible adolescent brain damage.
That fact would be chilling all on its own; it’s even more frightening when you factor in the well-documented increase in adolescent marijuana use in states where the drug has been legalized, either for medical or recreational use. Consider the following facts:
- In 2013, an average of 11.6 percent of Colorado youth (ages 12–17) had used marijuana within the last month. The national average was 7.15 percent.
- Colorado ranked third in the nation for adolescent marijuana use, 56.08 percent higher than the national average. (Compare those figures to 2006, when Colorado ranked fourteenth in the nation.)
- Since marijuana was legalized in Colorado, there has been a 24 percent increase in adolescent use.
- Nationwide, the number of adolescents (ages 12 and up) using pot within the past 30 days jumped from 14.5 million to 18.9 million.
- Marijuana is the number one drug documented in adolescent ER admissions and autopsy reports.
Targeting the Brain
Whether smoked or ingested, the active chemical in marijuana—delta-9-tetrahydrocannabinol, or THC for short—targets specific brain-cell receptor molecules, molecules that play a key role in the communication network critical to normal brain development and function. THC kicks these receptors into the red zone, potentially sparking a host of reactions:
- distorted perceptions
- psychotic symptoms
- difficulty with thinking and problem solving
- disrupted learning and memory
- impaired reaction time, attention span, judgment, balance and coordination
But here’s the kicker: Prolonged exposure to THC may speed up the age-related loss of nerve cells. The news gets worse.
Brain MRI studies done on adolescent recreational pot users show structural abnormalities—in gray matter density, volume, and shape—especially in areas tied to craving and dependence. The greater the marijuana use, the more significant the abnormalities. What’s more, changes in gray matter density have been measured in other regions of the brain, as well.
These adverse changes don’t just affect learning and memory during use; they can be observed long after pot’s acute effects wear off.
An important study published in 2012 by the National Academy of Sciences found that participants who used pot heavily during their teens and on through adulthood lost an average of eight IQ points between the ages of 13 and 38, while those who’d never used pot showed no drop at all. To rule out any pre-existing differences in IQ, researchers tested adolescents before they started using marijuana, then again after prolonged use.
Small wonder ACPEDS considers the results of the 2012 study strong evidence that pot use during adolescence—an age when the developing brain is still forming and deleting critical connections—can do long-term damage and lead to a substantial mental decline.
Marijuana poses a real danger to adolescents in other areas as well:
- an increased risk of schizophrenia
- impairment of judgment and coordination, doubling the risk of automobile accidents
- an increased risk of cardiac damage
- an increased risk of testicular cancer
- an increased risk of chronic coughs, respiratory infections, emphysema, and lung cancer
- an increased risk of sexual abuse/rape
- an increased risk of academic and occupational failure
Educate, Don’t Legislate
Unfortunately, too many parents (and healthcare providers) underestimate the serious risks pot poses to developing brains, unaware that today’s marijuana is three to five times more potent than it was in the 60s, with a THC content of up to 30 percent.
But given the documented increase in adolescent marijuana use, the scientific evidence of structural abnormalities and mental decline caused by its use, the American College of Pediatricians not only opposes the legalization ofrecreational marijuana, but strongly recommends “extreme caution in legalizing it for medical use.” Based on the same data, the American Academy of Child and Adolescent Psychiatry (AACAP) agrees. Finally, ACPEDs emphasizes the importance of educating the public about pot’s harmful effects on youth and the need to provide better access to proven treatments, instead criminally charging youthful offenders.
