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Cannabis smoking 'permanently lowers IQ'

Original post made by Sharon, Midtown, on Aug 27, 2012

"Teenagers who regularly smoke cannabis are putting themselves at risk of permanently damaging their intelligence, according to a landmark study.

Researchers found persistent users of the drug, who started smoking it at school, had lower IQ scores as adults.

They were also significantly more likely to have attention and memory problems in later life, than their peers who abstained.

Furthermore, those who started as teenagers and used it heavily, but quit as adults, did not regain their full mental powers, found academics at King’s College London and Duke University in the US.

They looked at data from over 1,000 people from Dunedin in New Zealand, who have been followed through their lives since being born in 1972 or 1973. "

Web Link

Based upon this evidence, use of legal pot should be restricted to those over 21 yrs-over 25yrs would be better still.

Comments (16)

Posted by Resident
a resident of Another Palo Alto neighborhood
on Aug 27, 2012 at 4:05 pm

Perhaps it is people of lower IQ that are the ones who choose to smoke it in the first place!

Posted by Sharon
a resident of Midtown
on Aug 27, 2012 at 5:03 pm

@ resident

This was a gold standard longitudinal study

IQs were measured in 1973 and at fixed intervals for the next 35 years-

There was a clear, significant, permanent loss of IQ in cannabis smokers.

From the study

“Quitting or reducing cannabis use did not appear to fully restore intellectual functioning among adolescent-onset former persistent cannabis users,” she said.

Although eight points did not sound much, it was not trivial, she warned.

It meant that an average person dropped far down the intelligence rankings, so that instead of 50 per cent of the population being more intelligent than them, 71 per cent were.

“Research has shown that IQ is a strong determinant of a person’s access to a college education, their lifelong total income, their access to a good job, their performance on the job, their tendency to develop heart disease, Alzheimer’s disease, and even early death,” she said.

“Individuals who lose eight IQ points in their teens and 20s may be disadvantaged, relative to their same-age peers, in most of the important aspects of life and for years to come.”

Web Link

The brain damage is personal, pervasive and permanent

Posted by Prohibition
a resident of Midtown
on Aug 27, 2012 at 5:47 pm


Education is good. Prohibition never works.

Posted by Gabe
a resident of another community
on Aug 27, 2012 at 5:52 pm

>Prohibition never works.

Agreed. That is why guns should not be banned...only the outlaws will have guns.

Posted by Sharon
a resident of Midtown
on Aug 27, 2012 at 6:06 pm

We have a wise prohibition protecting children from ingesting lead and other toxic metals and substances-cannabis is clearly toxic to developing brains.

Ingesting lead, like cannabis, causes brain damage and low IQ

The critical period in brain development is up to 25 yrs of age

We believe that pot should be decriminalized for those over 25 who know that it may still cause permanent brain damage-they can also smoke or eat lead if they want to.

For teenagers and those under 25 it is a very different matter.

In fact- selling lead containing products for ingestion with or without informed consent is a felony in California - the same felony statute should apply to those selling cannabis to those under 25 yrs

Posted by Outside Observer
a resident of another community
on Aug 27, 2012 at 7:41 pm

Obama said America has lost it's edge. Suppose this is why?

Posted by Musketeers
a resident of Green Acres
on Aug 27, 2012 at 7:42 pm

Gabe: You should be able to own as many muskets as you want. No prohibition.

Or these Web Link

A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.

100 round clips and assault rifles? That's just stupid.

Posted by Gabe
a resident of another community
on Aug 27, 2012 at 7:55 pm

Airight to bear INDIVIDUAL arms. However, the right can be regualted, according to the types of arms that the individuals can bear. Machine guns...probably not; semi-automatic pistols, concealed or not, is another matter. This is where the debate is, now.

However, prohibition will not work.

Posted by Musketeers
a resident of Green Acres
on Aug 27, 2012 at 8:13 pm

Prohibition of guns? Typical straw man fallacy. No one serious is calling for that.

100 round clips and assault rifles? That's just stupid.

Posted by Anon.
a resident of Crescent Park
on Aug 28, 2012 at 12:14 pm

I wonder if they did any comparison with users of tobacco and alcohol , and if the same pattern emerges it would seem to me to be due to the person, or their family environment.

Also, I watched a very interesting set of documentaries called "Unnatural Causes" where social status was used to track peolpe, and people with low social status were more stressed and developed a whole constellation of diseases that led to earlier death.

Why is it that someone's pet cherry picked study - of course, against marijuana, is published and a big deal is presumably being made of it? This has happened before lots of times.

These anti-choice propaganda pieces against marijuana only seem to help the marijuana producers and the drug cartels maintain their destructive cash flow. It is pretty clear there are enough people with enough money who will say or do anything to protect it that we all have to be extremely careful what we believe, and extremely diligent in comparing whatever claim of fact is being highlighted with the real world and other problems that exist or freedoms we want to maintain.

Posted by Gabe
a resident of another community
on Aug 28, 2012 at 2:28 pm

>Prohibition of guns? Typical straw man fallacy. No one serious is calling for that.

Try to get a gun permit in Washington, D.C. or Chicago. It is mostly only the crimnals that ahve guns in those cities (and other cities). Europe, without a Bill of Rights, has an effective ban on gun ownership for personal protection.

I think young people are much safer taking a hunter-safety gun handling course, and shooting guns, than they are by blowing weed. Maryjane is a serious demotivator among the young. It turns them into whiners and slackers, while they are demanding special attention, due to their special, 'discovered' knowledge.

Posted by Jan H.
a resident of Old Palo Alto
on Oct 8, 2012 at 6:44 pm

Not only does smoking marijuana lower IQ, from what I have observed over the last three decades is that it also takes away ambition. So then you have people with lower IQs who are also lazy. Not very useful to society, are they?

Posted by Sharon
a resident of Midtown
on Oct 8, 2012 at 6:54 pm

[Post removed by Palo Alto Online staff.]

Posted by a Sharon claim-read at your own risk
a resident of Crescent Park
on Oct 8, 2012 at 7:19 pm

What is Sharon talking about? Perhaps she can provide some proof for her assertion re women and independent voters, as well as get claim regarding Obama and put usage (oh wait, never mind, it is a Sharon diatribe- no proof will be provided).

Posted by Anon.
a resident of Crescent Park
on Oct 8, 2012 at 8:29 pm

It's marijuana, let's call it what it is, and it did not seem to lower Carl Sagan's IQ any.

- Wikipedia > Sagan was a user and advocate of marijuana. Under the pseudonym "Mr. X", he contributed an essay about smoking cannabis to the 1971 book Marihuana Reconsidered. The essay explained that marijuana use had helped to inspire some of Sagan's works and enhance sensual and intellectual experiences. After Sagan's death, his friend Lester Grinspoon disclosed this information to Sagan's biographer, Keay Davidson.

Since someone like Carl Sagan felt a need to keep this secret, there are likely many many other people out there that also secretly use marijuana. There may be something this study is picking up, perhaps, but I seriously doubt this is anything more than another attempt to influence public opinion towards maintaining the huge money stream that goes to DEA and to drug cartels.

If physical or mental harm is a measurement of how we should implement laws or law enforcement and not just a proganda ploy to manipulate people, for consistency's sake shouldn't we then demand something be done about alcohol, tobacco, non-fructose corn syrup, insecticides, preservatives and other chemicals that permeate our lives and bodies and some studies have proven are damaging in some way to us?

And looking at the methodology we use to evaluate toxicity of things in general, what kind of levels are we talking about, at what kind of dosage?

Looking at what has happened to Mexico, and has bled over the Mexico-US border we have better base our actions on real things, likes murder, bullets, guns, corruption, intimidation, etc. Let's end this idiotic sham of a drug war and if we want to keep troops in Columbia to be on ready to invade and repossess our South American resources that those pesky South Americans have demanded to have control of, then we ought to have the guts and honesty to just say that and move on from there.

God Bless America.

Posted by Anon.
a resident of Crescent Park
on Oct 8, 2012 at 8:30 pm

sorry ... meant to type: high-fructose corn syrup

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