While predominant attitudes among adolescents suggests that teenagers don’t see marijuana use as posing any long-term health risks, a new study suggests otherwise. A new study led by researcher Madeline Meier of Duke University found that adolescents who regularly use marijuana may experience a long-term decline in their performance on IQ tests.
In the study, participants were given IQ tests at age 13 and again at age 38. The only participants who posted significant declines in their IQ scores were those who used marijuana regularly prior to the age of 18. The researchers found no link between lowered IQ scores and regular marijuana use after the age of 18. Participants who used marijuana regularly before the age of 18 but quit using it in later life did not post higher IQ scores than participants who continued to smoke pot into adulthood, suggesting that any loss of cognitive ability cannot be recovered by ceasing marijuana use.
“I think this is the cleanest study I’ve ever read” that looks for long-term harm from marijuana use, said Dr. Nora Volkow, director of the National Institute on Drug Abuse, which helped fund the research.
Experts acknowledge that the study’s findings, while significant, are not definitive.