Bad News for Teen Potheads

A new study suggests that teens who routinely smoke marijuana risk a long-term drop in their IQ. Researchers didn’t see as much of an IQ drop for frequent users over the age of 18. Although experts said the findings are not definitive, they do fit in with signs that the drug is harmful to developing the brain. Study participants in New Zealand were tested for IQ at age 13, likely before any significant amount of drug use, and again at age 38. The mental decline between the two ages were in people who used pot before the age of 18.

Weed is the most popular illegal drug in the world, with somewhere between 119 million and 224 million users between the ages of 15 and 64 as of 2010, the United Nations reported. Within the United States, 23 percent of high school students said they’d recently smoked marijuana, making it more popular than cigarettes, the federal government reported in June.

The study surveyed data from over 1,000 people in New Zealand. In addition to IQ tests, they were interviewed five times between age 18 and 38, including questions related to their marijuana use. At age 18, over 50 of the participants admitted to being dependent on marijuana use. Over 90 others reported dependence at a later age. Researched compared their IQ scores at age 13 and at age 38 and noticed a drop only in the participants who became 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.

Analysis also showed that in participants who were dependent on marijuana by the age of 18 and who completely stopped using it by the age of 38, the IQ drop still occurred. The researchers also surveyed people who knew the study participants well at age 38. They found that the more often participants were rated as marijuana-dependent in the surveys over their lifetimes, the more memory and attention problems were noticed by their acquaintances over the previous year.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: