As more Americans are smoking marijuana than ever, several studies in the past few years painted the drug as potentially dangerous for young developing minds. However, a recent study of teenage twins contradicted those studies and found no evidence to back up the claims.
Last year, a study suggested that marijuana use in teenagers may lead to memory issues, loss of cognitive abilities, and a drop in IQ. However, a study at the University of Southern California contradicted the earlier findings. The study looked at sets of identical twins — one who smoked marijuana while the other abstained.
The study combated major flaws found in previous research. The twins allowed researchers to stabilize the factors of genetics and upbringing, which critics of other studies suggested could have just as much of an effect on development as the drug.
Looking at 789 pairs of twins involved in other studies, the researchers analyzed the twins looked at the twins five times, and asked them about their marijuana use, as well as use of other drugs and factors at home. Each time, the researchers also conducted an allegiance test to accompany the drug survey,
The results found that while the IQs of marijuana smokers dropped by about 4 points, the IQs of the non-marijuana smoking twin dropped about the same amount, suggesting that the drop was caused by another factor.
Although some researchers praised how the study was conducted, some criticized it for failing to monitor the effects of long term marijuana use. However, most have accepted the study as a “welcome addition to the literature” that proves that marijuana needs to be further researched.
“This does not mean that heavy use in adolescence is problem-free,” said Nicholas Jackson, the study’s author.
Although Jackson said “emerging evidence” suggested that marijuana had little impact on the brain, he added that “we desperately need more research on the effects that marijuana has on the brain.”
Featured image via livescience.com