Pubdate: Thu, 03 Sep 2015
Source: Boulder Weekly (CO)
Copyright: 2015 Boulder Weekly
Author: Leland Rucker


As more states and countries begin to engage in the issues associated 
with marijuana prohibition, it's important that lawmakers and 
citizens alike have the best possible information to be able to make 
wise decisions in public policy and in our everyday lives.

We don't know everything about cannabis yet. After decades of 
inactivity in the U.S., it needs serious, objective study. That said, 
it's pretty frustrating to see some of the often-repeated crap being 
produced on the subject today. In too many cases, it appears that the 
difference between "causality" and "link between" aren't part of the 
journalistic pallet anymore. If there's a link, there is cause.

That's why I'm encouraged by a recent series of reports released by 
the International Centre for Science in Drug Policy, and I urge 
everyone interested in the subject to read at least the summary if 
not the entire report. The group of scientists investigated the 13 
most repeated claims on cannabis use and then tried to determine if 
there were evidence to back them up. What they indicate is that there 
is little verification to back up most of the declarations that have 
become almost rote fact by now from sheer repetition.

Number one on my own list is that cannabis can lower your IQ by up to 
eight points. I see this one constantly, especially when the 
discussion centers around youth and marijuana use. It's a horrifying 
suggestion designed specifically to evoke the fear of god in a 
parent. But what the researchers found is that scientific evidence 
that suggests cannabis use is associated with declines in IQ is lacking.

As it turns out, almost all the headlines refer to one 2012 study 
that used an earlier study "to test the association between 
persistent cannabis use and neuropsychological decline and determine 
whether decline is concentrated among adolescent-onset cannabis 
users," according to the abstract.

Now writing a news story or headline that states that anything lowers 
IQ based on one study is problematic, but in this case, it's 
especially so. Even the study's author urged caution in 
interpretation. A tiny sample (38 people, representing 3.7 percent of 
the total study) doesn't really come up to the level of "Cannabis 
Destroys Brain Power and Lowers IQ" (Daily Mail) or "Study Shows 
Heavy Adolescent Pot Use Permanently Lowers IQ" (Forbes). (And what 
the hell is "brain power" and how is it quantified, anyway?) 
Researchers trying to duplicate the same experiment a year later 
found that the earlier study hadn't taken other socio-economic 
factors into account. The researchers also found a recent, larger 
study that found that alcohol use was associated with declines in IQ.

"Our findings suggest cannabis may not have a detrimental effect on 
cognition, once we account for other related factors, particularly 
cigarette and alcohol use," said researcher Claire Mokrysz of her 
2013 attempt at duplication. "This may suggest that previous research 
findings showing poorer cognitive performance in cannabis users may 
have resulted from the lifestyle, behavior and personal history 
typically associated with cannabis use, rather than cannabis use itself."

Another one I come across a lot is that cannabis use impairs 
cognitive function. On this one the results were inconclusive: The 
researchers found studies that offered moderate evidence that early 
onset and sustained use is associated with impairments and cognitive 
function but also found gaps in the evidence on the full range of effects.

"Given the current state of the scientific research, the simple 
assertion that cannabis leads to reduced cognitive function is 
misleading," they write. "It's also noteworthy that a systematic 
review of all longitudinal scientific studies on this topic found 
that the evidence did not support a causal relationship between 
cannabis use by young people and various psychosocial harms."

Another big claim I read about a lot and is currently listed on the 
SAM (Smart Approaches to Marijuana) website is that cannabis use, 
according to founder Kevin Sabet, "can result in serious, long-term 
consequences, like schizophrenia."

The researchers found some studies that point to a link between 
cannabis use and "the risk of symptoms associated with schizophrenia" 
and a more recent one that came to the opposite conclusion.

And, they note, if cannabis "caused" schizophrenia, we would be 
seeing those increases in the population as cannabis use rose, but 
that has not been the case. Research suggests that young people 
predisposed to schizophrenia may have their risk increased by using 
cannabis. That's hardly the same as Sabet's dire warning.

Lesson: If you're interested, read all you can about cannabis, but be 
skeptical of everything, too.

You can hear Leland discuss his most recent column and Colorado 
cannabis issues each Thursday morning on KGNU.
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MAP posted-by: Jay Bergstrom