Attention Kids: Smoking Pot Actually DOES Make You Stupid After All


We all remember the stoners, druggies, pot heads from high school—those dudes who sat in the back of the classroom, their clothes already reeking at 10 a.m. with the stench of the weed smoke that had just enveloped them out in the park, or behind the school, or (if your school was particularly bad) in the boys bathroom. They always seemed a little out of it, a little slow on the draw, surely headed for a life of not-much-of-anything.

Hell, forget about remembering them—maybe some of you were one of them?

Turns out that those stoners actually were doing irreparable harm to their brains. As we’ve been hearing for years, weed does kill brain cells if you start smoking it as a teenager.

A study of more than 1,000 people in New Zealand who were followed over two decades found that those who started habitually smoking marijuana before age 18 eventually showed an 8-point drop in IQ.

If you’re thinking that 8 points ain’t that bad—maybe worth giving up in exchange for all those years of a sweet, mind-dulling high—you should know this: Because the average IQ is 100 points, a drop of just eight points in IQ would mean falling from the 50th percentile to the 29th percentile in terms of intelligence. In other words, a drop from average to near-moron. (And since we’re talking averages, that means many of the subjects likely dropped a lot more than 8 points.)

The study, published yesterday in the Proceedings of the National Academy of Sciences, should be printed out and laminated by all those parents who are about to have that crucial anti-drug talk with their kids. If you’d rather use the more subtle approach, start slipping these facts into casual conversation around the family dinner table: Oh, you want me to get you some more juice? Did you know that pot will make you stupid?

Now all of you grown-ups out there who have become habitual pot smokers a little later in life—you know who you are!—and wondering if you have been zapping brain cells, you can rest a bit easier: Those who didn’t start smoking until after adolescence showed no adverse effects on intelligence. (But even knowing that, you still can’t remember where you put those keys, huh?)

The researchers started with a baseline intelligence for all study subjects, testing them when they were under 13 and hadn’t yet started smoking and then assessing them at five different “waves”—ages 18, 21, 26, 32, and 38. The researchers assessed marijuana use and tested intelligence. The authors also controlled for alcohol use, other drug use and education level.

According to the study, the eight-point drop was found in subjects who started smoking in adolescence and persisted in “habitual smoking”—using it at least four days per week—in three or more of the five testing waves. People who started smoking in adolescence but used marijuana less persistently still had a hit to their IQ’s, but it was less pronounced than the group that used it early and persistently.

Those who never used marijuana actually got smarter by nearly one IQ point on average.

Madeline Meier, lead researcher and a post-doctoral associate at Duke University, said that persistent use of marijuana in adolescence appeared to blunt intelligence, attention and memory. More persistent marijuana use was associated with greater cognitive decline.

“Collectively, these findings are consistent with speculation that cannabis use in adolescence, when the brain is undergoing critical development, may have neurotoxic effects,” Meier writes in the study.

Alarmingly, subjects who stopped using marijuana for a year still showed the persistence of adverse effects and some neurological deficits. But those who didn’t start smoking until after adolescence showed no adverse effects on intelligence.

Scientists believe they isolated the reason why this early use is so harmful. It has to do with a substance called myelin—which is a kind of insulation for nerve cells in the brain that also helps speed brain signals along. But in adolescent brains, the protective coating it forms is not yet complete.

We need to reach our kids as early as possible with this information because, according to statistics released in June by the U.S. Centers for Disease Control and Prevention, American teenagers today are more likely to be smoking marijuana than cigarettes. That’s because they think weed is less harmful than cigarettes. Now we know that’s not true.

So we must spread the word, as far and wide as possible: The next hit you take could mean a permanent spot working the fries at McDonald’s.


1. Marijuana in His Blood Reveals One Thing: Trayvon Martin Was Typical American Teen
2. What Bad Knees, Good Drugs, and Teenagers Are Made Of


Related Posts Plugin for WordPress, Blogger...

Denene Millner

Mom. NY Times bestselling author. Pop culture ninja. Unapologetic lover of shoes, bacon and babies. Nice with the verbs. Founder of the top black parenting website, MyBrownBaby.


  1. Can you cite the title of the study that you mentioned in this article? I would like to read it myself.

  2. This is actually information that has been proven Ill explain why and put links below for other people. Once again I’m not talking on opinion but rather fact. Nor do I care for opinion but rather fact 🙂

    Effects on Life

    Research clearly demonstrates that marijuana has the potential to cause problems in daily life or make a person’s existing problems worse. In fact, heavy marijuana users generally report lower life satisfaction, poorer mental and physical health, relationship problems, and less academic and career success compared to their peers who came from similar backgrounds. For example, marijuana use is associated with a higher likelihood of dropping out from school. Several studies also associate workers’ marijuana smoking with increased absences, tardiness, accidents, workers’ compensation claims, and job turnover.

    Marijuana, Memory, and the Hippocampus

    Memory impairment from marijuana use occurs because THC alters how information is processed in the hippocampus, a brain area responsible for memory formation.

    This is an image of a rat brain with the different parts of the brain labeled.
    Distribution of cannabinoid receptors in the rat brain. Brain image reveals high levels (shown in orange and yellow) of cannabinoid receptors in many areas, including the cortex, hippocampus, cerebellum, and nucleus accumbens (ventral striatum).
    Most of the evidence supporting this assertion comes from animal studies. For example, rats exposed to THC in utero, soon after birth, or during adolescence, show notable problems with specific learning/memory tasks later in life. Moreover, cognitive impairment in adult rats is associated with structural and functional changes in the hippocampus from THC exposure during adolescence.

    As people age, they lose neurons in the hippocampus, which decreases their ability to learn new information. Chronic THC exposure may hasten age-related loss of hippocampal neurons. In one study, rats exposed to THC every day for 8 months (approximately 30 percent of their life-span) showed a level of nerve cell loss (at 11 to 12 months of age) that equaled that of unexposed animals twice their age.

  3. no no no you can not tell the kids that marijuana use is bad not it is not bad i started smoking when i was 17 years and i passed my exams it made me very smarter in make me aware of myself and i am always content with what i have i smoke weed everyday it never made me dump.My father smoked weed all his life and he is a successful business man weed never makes you dump they are a lot of great stars in the world that smokes marijuana and that does not make them dump it gives you different ideas it motivates you as a person helps you to release stress .it heals asthma,tetanus cancer and all sort of diseases and it is legalized in California because they found out the importance of marijuana use.weed never ever will make you dump it is difficult for you to get sick if you smoke marijuana always you can all investigate what i am saying and see for yourself.the fuss and bad thoughts about marijuana are all lies they are all hypocrites they all smoke marijuana but they are hiding it bob Marley was never dump Rihanna is not dump and allot of stars use it president Barack Obama smoked marijuana so please stop confusing people and give scientists and researches the chance to investigate and find out…..

    • If ever there was an argument for how marijuana makes you… um… dumb… your post is it, Larry. Dude—get some punctuation in your life. And spell check. And maybe call a friend for a clue, because your post is all kinds of wrong.

    • How did you keep typing “dump”? P and B aren’t even close to each other. I honestly thought this post was a joke because the spelling and grammar is hilariously wrong while you are arguing that smoking weed didn’t make you “dump”. Learn how to write basic sentences before you go on a rant about how intelligent you and your stoner dad are.

  4. Cigarettes are more harmful than weed so your fact at the end there is wrong and irresponsible. I’m currently in college and I smoke pretty much everyday because its a huge stress reliever when I come home from a long day of school or work. I can honestly tell you that I have accomplished more than half the students in my college.(Alabama) I have worked for a two-time academy award winner and am on the deans list. While there are some stupid pot heads out there like Larry up there, the same could be said of those who don’t smoke. We just don’t blame it on pot. Two of our greatest presidents smoked pot habitually.(George Washington, Thomas Jefferson) I don’t think it’s the scourge of society your making it out to be but I understand you’re a mom and where you are coming from. Btw my mom knows I smoke pot and would rather have me smoke then drink my self to death in typical college fashion.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.