This is your brain — it looks just like your brain on weed.
Marijuana doesn’t seem to have an effect on teenagers’ IQs, according to a new study.
A team of scientists tracked pairs of twins, made up of one marijuana-user and one abstainer, and found no measurable link between using the drug and having a lowered IQ.
The study was released Monday by the Proceedings of the National Academy of Sciences. Some prior research has led to suggestions that the developing adolescent brain is particularly vulnerable to harm from marijuana.
But the researchers — a team of scientists based in California, Minnesota and Pennsylvania — found that while pot users lost about four IQ points over a decade, their abstaining twins’ intelligence similarly declined.
The team suggested pot smoking may be merely a symptom of something else that’s really responsible for a brainpower effect seen in some previous research.
It’s not clear what that other factor is, said Joshua Isen, an author of the analysis.
But an adolescent at risk for smoking pot “is probably going to show this IQ drop regardless of whether he or she is actually smoking marijuana,” said Isen, a lecturer in psychology at Loyola Marymount University in Los Angeles.
The scientists focused on 290 sets of twins who were given a battery of intelligence tests at ages 9 to 12 — before any of them had used pot — and again at ages 17 to 20.
They tracked the twins’ test scores over time and found that marijuana smokers did not fare any worse than their abstaining siblings. If a pot user’s intelligence declined, their sibling’s likely did, too.
So, the researchers concluded, pot smoking itself does not appear responsible for declines in test scores.
Isen noted, however, that the work says nothing about other potential harmful consequences of smoking marijuana in adolescence.
With News Wire Services
