Worried about all that weed you smoked in high school? Maybe you shouldn’t be. According to a new study, cannabis has less effect on young brains than once believed. This report compiled data from a host of previous studies on chronic use. Their findings offer encouraging findings on teenage and young adult cannabis use. Here’s what we know so far about cannabis’s effect on brain development.
Marijuana’s Short-Term Effect
This research, published by JAMA Psychiatry, took data from 69 previous studies into account. All these studies considered significant marijuana use’s influence on brain function. According to study author Cobb Scott, “this is the first one [study] to be done specifically in adolescent and young adult samples.”
How does marijuana affect cognitive function? The subjects that self-identified as frequent cannabis users had slower processing speeds, and experienced more difficulty learning, remembering, paying attention and conceptualizing than those who did not smoke marijuana.
The study focused on the subjects’ executive functioning skills. Assistant professor of psychiatry at the University of Pennsylvania Cobb Scott explained to CNN, “We basically showed that the largest effects—which was around a third of a standard deviation—was in the learning of new information and some aspects of executive functioning, memory and speed of processing.”
Cognitive Function Reduces Only For 72 Hours
However, after stopping marijuana use for 72 hours, the difference in cognitive function between heavy cannabis users and non-users is no longer discernible. These findings contradict earlier studies that could distinguish between frequent marijuana consumers and non-consumers after the 72 hour period.
Scott hypothesizes, “some of the effects found in previous studies may be due to the residual effects of cannabis or potentially from withdrawal effects in heavy cannabis users.” This means that earlier studies’ subjects still felt cannabis’ influence, which skewed the evaluation of their cognitive function.
Earlier Studies Present Opposing Findings
This is only the latest in a series of studies on the effects of cannabis on cognitive function. Three separate studies contend that marijuana use is dangerous for developing brains.
A 2008 study published in Addiction Biology linked marijuana use during puberty to a higher risk of psychiatric disorders and negatively affected cognition. It also suggested that marijuana use at a young age leads to more illegal drug use and cannabis dependency.
Another study from 2012 compared the IQs of marijuana users and non-users from ages 13 to 38. It founds that people who used cannabis as adolescents had, on average, lower IQs by 8 points. According to NPR, the scientific community panned this study because it did not factor in income or home life.
Effects of Cannabis On the Adolescent Brain from 2014 also claimed that cannabis use affects brain development and functionality. This report argued that marijuana use has a long-term impact on cognition, specifically by altering prefrontal cortex development.
President of Smart Approaches to Marijuana and Yale professor Kevin Sabet warns, “There have been very important studies showing evidence for irreversible damage (from marijuana use), and so there needs to be more research in this area.”
Other Scientific Work Doesn’t Find That Marijuana Has Long-term Negative Effects
The most recent study that found that cannabis has less effect on young brains than once believed isn’t the only study with these findings. Nicholas Jackson of the University of California, Los Angeles compared sets twins. One twin in each set used marijuana, while the other didn’t.
The study did not find that the twin who used marijuana had a lower IQ.
Final Hit: Cannabis Has Less Effect on Young Brains Than Once Believed, Study Says
The effect of marijuana on young brains is one of the more thoroughly explored areas of cannabis research. Despite this, we cannot, with certainty, conclude that cannabis use has long-term effects. However, the size of this most recent meta-analysis suggests that cannabis has less impact on young brains than once believed. Published at a critical moment in cannabis history, this study could sway voters towards legalization.
