
Study: Teen Cannabis Users Have Poor Long-Term Memory in Adulthood - hecubus
http://www.feinberg.northwestern.edu/news/2015/03/Csernansky-teen-cannabis-use.html
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AceJohnny2
Ugh. I'm all for legalization, but the public discourse has skewed the risk
perception of it. OK, it may not be as bas as alcohol, but that certainly
doesn't make it harmless.

For people who have access, I highly recommend this review article from June
2014 in the New England Journal of Medicine, arguably the most respected
scientific medical publication in the world, which goes over the published
scientific litterature about Marijuana: bottom line, it's not as innofensive
as some make it to be, and adolescents are most at risk. Caveat Emptor.

[http://www.nejm.org/doi/full/10.1056/NEJMra1402309](http://www.nejm.org/doi/full/10.1056/NEJMra1402309)

(personally, I do believe it should be legalized for policy and social
reasons, but that doesn't mean I think it's biologically harmless)

~~~
mlmonkey
The problem is: the USG _prevents_ research in the area. It is extremely hard
to get permission from the DEA to research the effects of MJ.

I don't believe anyone is claiming that MJ is harmless; but that overall, MJ's
harm is lesser than the harm caused by alcohol or tobacco. Teens are already
known to be more susceptible to chemical substances because of their
developing brains, so this study doesn't seem to be very surprising.

~~~
DanBC
> tobacco

Why would cannabis be less harmful than tobacco? The smoke from each is
roughly the same, with the obvious differences being nicotine in tobacco and
cannbinoids in cannabis.

Maybe cannabis smokers smoke less frequently than cigarette smokers; but maybe
they inhale the smoke deeper and hold it longer.

It's a bit frustrating that anyone who expresses any concern about cannabis is
written off as a propagandist of an oppressive government.

(I'm pro legalisation)

~~~
jonnathanson
Smoke for smoke, cannabis and tobacco are probably equally harmful. It's the
combustion of plant matter and the inhalation of smoke, not the nicotine _per
se_ , that makes tobacco so harmful. The same applies for smoked cannabis, and
indeed, some studies have found cannabis smoke slightly more harmful in that
regard, in so far as cannabis isn't usually smoked with a filter.

But unlike tobacco, cannabis does not contain a chemical as highly addictive
as nicotine. Your average tobacco smoker probably smokes an order of magnitude
more tobacco than your average cannabis smoker smokes cannabis. Evidently
there _is_ a nonzero risk of physical or psychological dependency for
marijuana, but it's nowhere near the risk profile of tobacco.

~~~
peteretep

        > Smoke for smoke, cannabis and tobacco are probably
        > equally harmful.
    

I feel like you're disagreeing with the article.

If you smoke heavily from 14 and quit at 18, your health risks from tobacco
will normalise to that of a non-smoker after x years, but there's a suggestion
here that if it's cannabis you're smoking, you've caused yourself irreparable
harm

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jMyles
> Young adults who abused cannabis as teens performed about 18 percent worse
> on long-term memory tests than young adults who never abused cannabis.

Wonderful. Another study with no basis for distinguishing causality from
correlation.

I bet you can randomly select a subgroup of 18-percent poorer performers and
find that they have all sorts of things in common, from diet to exercise to
presence or absence of parents - as well as bizarre factors like who was born
on a Tuesday.

There are probably dozens of markers that both correlate with these kinds of
results and also plausibly suggest an explanation.

> “It is possible that the abnormal brain structures reveal a pre-existing
> vulnerability to marijuana abuse,” Smith said. “But evidence that the longer
> the participants were abusing marijuana, the greater the differences in
> hippocampus shape suggests marijuana may be the cause.”

What?! No it doesn't. It suggests quite the opposite: that people with greater
abnormality tend to use marijuana longer.

I suspect that, now that medical cannabis is widely available and somewhat
widely used in the treatment of childhood maladies, we may begin to see, in
the next decade or so, results based on much sounder science simply because of
the availability of higher quality sample groups.

~~~
xalloc
When people don't like the result of a study, the very existence of
"causality" all of sudden turns into a point of contention.

~~~
jMyles
It's true that I don't like the result of this study. My experience is that
plenty of healthy, smart, motivated, effective people consume cannabis quite
regularly. I have been smoking marijuana quite regularly since I was about 19
years old (which is 13 years ago now) and of course I don't like to think of
myself as cognitively impaired.

However, I think that studies like this are particularly vulnerable to this
critique of methodology. Any time you assess the performance of a large group
and then divide that group into subgroups, you are going to find trends of
varying levels of statistical significance.

It is incredibly easy to do.
[http://www.tylervigen.com/](http://www.tylervigen.com/)

That is why, in every scope-and-methods class in every college across the
country, the various methods for ascertaining causality are demonstrated and
taught.

Reading only the linked article and not the study itself, I so far have the
impression that none of these were seriously considered - presumably on the
basis of ethical treatment of humans subjects. You can't just take a group of
people with a particular set of desirable control features (perhaps, in this
case, a typically shaped hippocampus) and force-feed them cannabis smoke for
three years.

On the other hand, it's just as easy to read this study as meaning that people
who performed poorly on the relatively specific requirements of this study
seemed to prefer to smoke marijuana. If this study were about serious science,
the conclusion might be the utterly uninteresting sky-is-blue headline,
"absent-minded people likely to smoke weed."

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johndevor
An excellent book on the topic of drug abuse is Gabor Mate's, In the Realm of
Hungry Ghosts. He makes a convincing argument that the majority of drug users
are struggling with severe early trauma. Given this study and Mate's book, it
may just be that traumatized people are looking for ways to forget. They could
be seeking the forgetfulness as exactly what they want. This is different from
saying that memory loss is necessarily a bad, unintended consequence.

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stevedekorte
The difference between a medicine and a poison is dosage.

"Binging Alcohol Abuse Leads To Loss Of Working Memory In Teens":
[http://www.medicalnewstoday.com/articles/231267.php](http://www.medicalnewstoday.com/articles/231267.php)

~~~
sliverstorm
Medicine dosage is critically important, but do you mean to imply any poison
can be good for you in small enough amounts?

 _No safe blood lead level has been identified._

\--
[http://www.cdc.gov/biomonitoring/Lead_FactSheet.html](http://www.cdc.gov/biomonitoring/Lead_FactSheet.html)

Which, tangentially, reminds me of "Unsafe at any Speed"

~~~
coldtea
> _Medicine dosage is critically important, but do you mean to imply any
> poison can be good for you in small enough amounts?_

He said "the difference between a medicine and poison".

Not between "poison and a medicine".

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Will_Do
This seems to be a simple correlational study with the added bonus that
abnormal hippocampi is also correlated with pot usage.

There isn't even an attempt to establish any sort of causality here yet the
article uses the word 'affects'.

~~~
trjordan
“It is possible that the abnormal brain structures reveal a pre-existing
vulnerability to marijuana abuse,” Smith said. “But evidence that the longer
the participants were abusing marijuana, the greater the differences in
hippocampus shape suggests marijuana may be the cause.”

Correlation, sure, but correlation with length of usage. Definitely a more
interesting angle than simply usage <-> deformation.

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shillster
It will be great when this substance can be officially studied in a clinical
setting but so long as its a schedule 1 substance at the federal level, well,
its worse than methamphetamine (on paper).

~~~
tptacek
[http://medicalmarijuana.procon.org/view.resource.php?resourc...](http://medicalmarijuana.procon.org/view.resource.php?resourceID=000884)

(Also, in what way is cannabis worse on paper than methamphetamine?)

~~~
MichaelGG
In the US, methamphetamine is Schedule II, and legal to prescribe (indicated
for use in ADHD or obesity, trade brand Desoxyn).

Pot is Schedule I, indicating no medical use and strictly prohibited.

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arasmussen
I find it really interesting that this jumps to the top of Hacker News. I
wonder if it's because:

\- This study is self-serving for people who are anti-marijuana or

\- Hacker News users tend to be interested in or users of marijuana and find
this study concerning

I'd guess a bit of both but more the latter since the Hacker News community
tends to be quite liberal.

~~~
snlacks
I would guess it's an area ripe for start ups in each new state where it is
legalized/decriminalized.

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datashovel
I'm not certain this paper I'm referencing is the same one referenced in this
thread's article, but the doctor was a collaborator on this:

44 healthy controls, 10 subjects with a CUD history, 28 schizophrenia subjects
with no history of substance use disorders, and 15 schizophrenia subjects with
a CUD history

[http://schizophreniabulletin.oxfordjournals.org/content/40/2...](http://schizophreniabulletin.oxfordjournals.org/content/40/2/287)

I'm no scientist, but it seems a little presumptuous to me to say I've come to
a general conclusion about anything when all I have to investigate are 25
people. To quote the above "10 subjects with a CUD (Cannabis Use Disorder)
history,... and 15 schizophrenia subjects with a CUD history".

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datashovel
I'm not saying this to try to discredit this or any other study, but I think
it would be appropriate for publications, universities, hospitals, doctors
whose names are on studies to disclose affiliations. Especially with
contentious issues like marijuana.

After a brief Google search I found other studies where this same doctor (John
Csernansky, MD) has linked marijuana use to "Schizophrenia-like Brain
Changes".

[http://www.medscape.com/viewarticle/818082](http://www.medscape.com/viewarticle/818082)

~~~
swatow
How is that an "affiliation". Isn't it natural that people tend to publish on
the same topic?

~~~
datashovel
Like I said in the original comment, I'm not trying to discredit anyone or
even this particular study. I'm simply seeking a more deliberate model of
transparency. That also goes for studies who may claim that marijuana is
healthy or "less harmful" than other products.

This guy has over the course of several years come up with very damaging
evidence that marijuana is irreversibly harmful to humans. To start with, to
know who these studies are funded by would be helpful so I can know whether it
deserves my attention.

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rjurney
Sometimes I wonder what a booze/pot/acid/ecstasy free me would be like. Binged
on all of them as a teenager. Would I be 10% smarter? 20%? More? Better moods?

~~~
giarc
"n of 1" story. One summer between semesters at university, my room mate and I
really took up smoking weed. After about a month or two, I really noticed a
difference in myself mentally. Took longer to think things through, many more
"That was stupid moments" etc. I decided to stop then and it all seemed to go
back to normal.

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phirschybar
is this really news? :)

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roneesh
This from the medical journal "Duh".

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inthewoods
I'm sorry what page am I on? What is this website?

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magic_beans
Exactly why it should be illegal for ADOLESCENTS. Not for adults over the age
of 18.

~~~
paulhauggis
I'm good with this, as long as you also don't expect the tax payers to pay for
your medical bills when you have medical issues due to your long-term MJ
usage.

~~~
chrisbennet
_" I'm good with this, as long as you also don't expect the tax payers to pay
for your medical bills when you have medical issues due to your long-term
Sedentary Lifestyle."_

Fixed it for you. ;-)

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lewaldman
Yeah... being there, I'm like... Wait... about what we were talking??

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mattbgates
Prescription drug users also experience memory loss and poor long-term
effects. Though I did smoke quite a bit when I was younger.... uh... forgot
what I was gonna say ;)

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binarytrees
I think there needs to be more studies. I'm sure Cannabis does effect
development of the brain during adolescence, but does the brain recover over a
period of time or is it perm dramage.

