

Young cannabis smokers run risk of lower IQ, report claims - ColinWright
http://www.bbc.co.uk/news/health-19372456

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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? The answer is that people may 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:

[http://jonlieffmd.com/blog/new-brain-cells-many-triggers-
for...](http://jonlieffmd.com/blog/new-brain-cells-many-triggers-for-
neurogenesis)

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.

None of this is meant to condone drug use, only to criticize very sloppy
science that draws a conclusion not remotely supported by the work.

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

