Adolescents Category in Blog

Adolescent Marijuana Use Lowers IQ

Scientists in New Zealand have concluded that adolescents who smoke pot will end up with a lower IQ by the age of 38. Researchers followed a group of 1,037 children born in Dunedin, New Zealand between 1972-1973. They tested the children’s IQs at ages 7, 9, 11, and 13 (before onset of marijuana use) and again at age 38 (after several had engaged in marijuana use). Even accounting for disparities in education, users who picked up marijuana as adolescents and used it consistently over the years saw an average decline in IQ of 8 points. Those who started smoking marijuana as adults did not experience the same decline. The most telling outcome, however, was that discontinued use after adolescent-onset did not restore brain functioning to previous levels. In other words, there is no going back.

The scientists, led by Madeline Meier of Duke University, defined adolescent-onset cannabis use as either “dependence before age 18 or weekly cannabis use before age 18”. The unfortunate duality of reported drop in perceived harm towards pot use as well as younger and younger users provoked the study. Now, Meier and her team feel the results call for more studies on reversing the effects. A drop of 8 IQ points moves the average person from the 50th percentile in intelligence to the 29th percentile. “Somebody who loses 8 IQ points as an adolescent may be disadvantaged compared to their same-age peers for years to come,” Meier said.

At FI, we know that “Just Say No” feels old-fashioned to many adolescents. With today’s peer pressures and again, the lack of perceived harm, “saying no” may be more challenging than it was even 10-15 years ago. But drugs have changed. Marijuana potency has risen 175% since 1992. Plus, stats show that 14.2% of 8th graders have already experimented.

We can’t be with them all of the time, but when they are with us, we have to let kids know pot isn’t worth it. There is just too much at stake.