A well-done study published in the Proceedings of the National Academy of Science has concluded that
using marijuana lowers IQ if it’s started at an early age – teen years – and if
the use of marijuana continues for many years afterwards.
But interestingly, heavy regular marijuana use had no
effect on IQ in this study if it’s use started during the adult years.
Why the difference?
Well, as many other studies have shown, a young developing
brain is generally more susceptible to toxic effects from any source than an
already fully-developed brain (although one could argue, based on listening to
call-in talk shows, especially sports call-in shows that most adult brains have
a long way to go before they can be considered “developed”).
The neat thing about this study, by the way, is that it
did a good job in controlling for factors that have often bedevilled other
studies looking at marijuana effects, such as for example, different education
levels (in this study, high school graduates and those who didn’t finish high
school both had a drop in IQ if they started smoking dope as teens).
And the effect on teenage brains was not minimal: there
was an IQ drop of 8 points in smokers, which is quite substantial, compared to
a rise in the IQ scores of kids who never used marijuana.
Anyway, just another reason to advise your kids to avoid
using marijuana.
And you should keep telling them that because studies show
that despite what they may tell you, kids actually listen to their parents.
