MYNORTHWEST NEWS

New study finds pot smoking leads to lower IQ

Aug 28, 2012, 7:01 AM | Updated: 12:41 pm

A new study show long-term marijuana users who started before they were 18 suffered an average 8 point drop in IQ score. (AP image)

(AP image)

That’s why they call it dope. A new study suggests teenagers who smoke a lot of pot could be doing permanent damage to their brains.

The decades-long study of 1,000 New Zealanders
seems to show if you smoke marijuana heavily as a teen, your IQ drops by about 8 points and that drop persists into adulthood even after you’ve quit.

“Those who started as teenagers had not by age 38 gone back to the kind of intellectual abilities that they had as primary school pupils,” Professor Terrie Moffitt, a lead researcher in the study tells CBS.

It probably comes as no surprise that heavy pot smokers have problems with memory, concentration and overall brainpower but this study indicates that the negative effects are more lasting if you started as a teenager. People who start smoking marijuana as adults do not experience the same lasting effects. There is no noticeable drop in IQ for them.

Earlier studies found a link between mental ability and pot smoking but did not establish any cause and effect relationship.

More than 1,000 study participants from New Zealand were tested for IQ at age 13 – likely before any significant marijuana use – and again at age 38. All were born in the town of Dunedin during a year-long span ending in 1973.

In addition to IQ tests, participants were given five interviews between ages 18 and 38, including questions related to their marijuana use. At age 18, 52 participants said 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.

The study comes as Washington state voters prepare to vote on a new initiative legalizing and regulating marijuana in the state.

The Associated Press contributed to this report

MyNorthwest News

Image: Brightly colored eggs are set on a table on the South Lawn of the White House in Washington,...

Ted Buehner

Expect good Easter weekend weather for egg hunts, chilly evening Mariners games

Both Saturday and Sunday of Easter weekend will feature temperatures warming to around 60 degrees across much of Western Washington.

6 hours ago

Taylor Swift performs onstage during the Taylor Swift | The Eras Tour at Lumen Field on July 22, 20...

Micki Gamez, KIRO Newsradio and Bill Kaczaraba, MyNorthwest

Seattle tourism dollars break records following All-Star Week, Taylor Swift

It was a record-setting year for dollars flowing into Seattle from tourists.

7 hours ago

Image: A bridge in Carnation....

Julia Dallas

Carnation frustrated with Seattle again after 8th false emergency alarm induces widespread panic

Carnation citizens have faced a series of panic-inducing alarms after SPU's system for the Tolt Dam falsely sounded eight times.

9 hours ago

Grocery store shopper...

Bill Kaczaraba

Ways to deal with Seattle grocery store sticker shock

Seattle grocery store sticker shock continues to play havoc on locals, but there are ways to counter high prices.

9 hours ago

belltown hellcat social media...

Frank Sumrall

Infamous ‘Belltown Hellcat’ social media influencer charged with reckless driving

The social media influencer has been accused of driving 107 miles per hour through Belltown in a Dodge Hellcat.

10 hours ago

KIRO Newsradio gracie awards...

MyNorthwest Staff

KIRO Newsradio anchors receive Gracie Awards for outstanding work

Heather Bosch and Lisa Brooks, anchors at KIRO Newsradio, have been honored by the Alliance for Women in Media with prestigious Gracie Awards.

13 hours ago

New study finds pot smoking leads to lower IQ