Would you experiment with marijuana if you knew that it would lower your IQ? It would sure make me think twice. This appears to be the case.
A recent study found that teens who routinely smoke marijuana risk a long-term drop in their IQ. As reported in www.stltoday.com.
The researchers didn't find the same IQ dip for people who became frequent users of pot after 18.
The study took place in New Zealand and IQ was tested at age 13, likely before any significant marijuana use, and again at age 38. The mental decline between those two ages was seen only in those who started regularly smoking pot before age 18.
There is certainly a pervasive feeling among American youth that marijuana use is not risky.
While these new findings aren't definitive, they underscore the importance of studying how marijuana may harm young people.
The Study
The study drew on survey data from more than 1,000 people in New Zealand, everybody born in the town of Dunedin during a year-long span ending in 1973.
At age 18, 52 participants indicated they had become dependent on marijuana, meaning that they continued to use it despite its causing significant health, social or legal problems. Ninety-two others reported dependence starting at a later age.
Researchers compared their IQ scores at age 13 to the score at age 38 and found a drop only in those who had become dependent by 18.
Those deemed dependent in three or more surveys had a drop averaging 8 points. For a person of average intelligence, an 8-point drop would mean ranking higher than only 29 percent of the population rather than 50 percent.
Among participants who'd been dependent at 18 and in at least one later survey, quitting didn't remove the problem. IQ declines showed up even if they'd largely or entirely quit using pot at age 38.
The moral of this story is to never start using marijuana, but most-certainly let’s keep kids off marijuana at a young age. More underage drug classes are a part of the solution.