

Pot permanently lowers IQ - aginn
http://www.telegraph.co.uk/health/healthnews/9426205/Cannabis-smoking-permanently-lowers-IQ.html

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lutusp
The title of the article in no way reflects the outcome of the research. The
study compared measured IQ to a _decision to smoke pot_. There is no control
group, and the study is retrospective.

A reader may ask how this result could arise by something other than a cause-
effect relationship? Maybe people find themselves under peer pressure to (a)
smoke pot, and (b) reject the value of scholarly activities. Someone might
answer that IQ is predetermined, that it doesn't have any environmental
component. But that idea has been falsified in animal studies, studies that
show the development of new brain cells in animals that live in stimulating
environments.

There are any number of factors that might lead an individual to
simultaneously choose to smoke pot and avoid activities that might improve his
IQ -- socioeconomic, genetic, and so forth. The only way to control for these
things is to design a truly scientific study that _tells_ experimental
subjects whether they will smoke pot, rather than _asking_ whether they do.
But such a study would be unethical, which is why there's no science in this
field of study.

This study is much like thousands of studies I've read over about 35 years,
and all of them suffer from the same flaw -- they aren't science. Correlation
is not causation.

The linked study represents psychology at work -- science in name only.

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richardjordan
I suspect many will be skeptical of this research as it's almost become an
article of faith that pot smoking is harmless and all criticism to the
contrary is merely party-pooping oppression.

One of the things that often concerns me about Silicon Valley in recent years
has been the trend of many startups where pot smoking is part of the
established culture of the company. I don't think it's a majority, but it's
certainly more than I'd realized previously and it certainly seems to be a
more recent trend.

I'm not a vehement prohibitionist by any means. However, I've been burned by a
co-founder showing up stoned to a key meeting with an investor who'd committed
a 6-figure sum out of his own pocket to get the company to where it was. That
was a problem.

Maybe it's just me aging - I am not a big drinker nowadays, after going
through the same college years everyone else did where drinking was involved
in so much social activity - but over the years I've arrived at the belief
that much of the time wasted stoned, by folks convinced this is making them
more creative, is time that could be put to better use.

Feel free to do what you want to do, sure. But reminding people that there are
negative consequences is never a bad thing.

~~~
logical42
Oh I'm skeptical all right...but not because it's 'party pooping' opposition,
but because the article infers from a study which shows a correlation between
continual sustained use of marijuana and a decrease in I.Q. to the rather
illegitimately drawn conclusion that smoking marijuana prior to the age of 18
causes you to get stupider as you age.

I have primarily two objections.

First, the article fails to rule out:

\- The possibility that people who start smoking pot prior to the age of
eighteen and continue to smoke are just generally likely to be the type of
person who might get stupider with age anyway.

Second the argument fails to consider:

\- That an alternative explanation could explain the facts of the study
equally well: namely, that it's not the age at which one begins to smoke which
causes this IQ decrease but rather that it is the _sustained_ use of marijuana
which is actually damaging.

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tokenadult
I was surprised to find out that this study finding comes from a long-running
longitudinal study

[http://dunedinstudy.otago.ac.nz/news/dunedin-study-theme-
lea...](http://dunedinstudy.otago.ac.nz/news/dunedin-study-theme-leaders-win-
us1-million-klaus-j-jacobs-research-prize-for-productive-youth-development)

that has produced some other path-breaking research papers on child
development. In other words, while this study is not the last word on the
subject of the headline here, it is conducted by researchers who are used to
scholarly controversy and having other researchers check their work. So I'll
be curious to check the underlying journal article (for which I have yet to
see a citation in any of the several news reports about this today).

~~~
lutusp
> it is conducted by researchers who are used to scholarly controversy and
> having other researchers check their work.

Repeating a study with no meaningful controls ignores the same factors, and
doesn't change the outcome -- until a prospective double-blind study is
carried out, we don't have anything except a correlation, and a correlation is
not a cause-effect relationship.

Here's a perfectly plausible explanation that the research ignores --
individual who _choose to smoke pot_ are under peer pressure to avoid
intellectually stimulating activities. The latter factor causes their measured
IQ to drop, compared to others who embrace a lifestyle with more intelligence-
enhancing activities.

Is that possible -- can an individual improve his IQ by choice of activities?
Yes, according to animal studies that do have meaningful controls -- animals
that are placed in stimulating environments _grow new brain cells_ :

<http://www.pbs.org/saf/1101/segments/1101-2.htm>

It doesn't matter how many times such drug use studies are conducted or
replicated -- if they have the same systematic flaws, repetition doesn't
increase their value.

The gold standard for this class of study is a double-blind, retrospective
study, and such a study _has never been conducted_ for ethical reasons.

This study is typical "psychological science" -- science in name only.

~~~
lutusp
Correction to the above: when I said "double-blind, retrospective study", of
course I meant "double-blind, prospective study".

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benologist
So does bringing reddit-flavored content to HN!

