Cannabis Use: Is It Really Safe? Part 4

Earlier this year, I pointed out a study looking at how moderate-to-heavy use of marijuana might have a negative impact on lung function.  Well, in a case-cohort study of 1,037 Kiwis followed from birth to 38yo just published online earlier this week in the Proceedings of the National Academy of Sciences, the authors concluded that consistent & persistent use of marijuana starting in adolescence led to a decrease in cognitive function later on in adulthood.

The authors arrived at their conclusion by assessing cognitive function in everyone at 13yo, prior to initial use of marijuana and again at 38yo.  Those who initiated use as an adult did not demonstrate the same cognitive impact as those who started in their teens.  More importantly, stopping marijuana use did not improve cognition.

Interestingly enough, the topic of marijuana use came up during one of the sessions during our recent NAFP Summer CME Conference.  While the speaker pointed out (and I'm obviously paraphrasing from my addled brain 2 weeks later) that no studies had demonstrated any benefit from cannabis, the audience member noted that it's impossible to perform a legitimate randomized, double-blind, placebo-controlled trial involving the use of a Schedule I substance.

Which brings up a very interesting conundrum.  With menopausal hormone therapy, we had plenty of observational studies demonstrating benefit such that is was imperative that we perform a randomized, double-blind, placebo-controlled study to confirm (or disprove) this association as well as prove causality.  But if we look at marijuana, do we have enough observational studies demonstrating benefit, at least enough to warrant performing a randomized double-blind, placebo-controlled study?  Granted, we only see what we want to see but I've only stumbled on data suggesting minimal-to-no benefit aside from reports of benefit in nausea & glaucoma.  So we don't have any studies linking marijuana use to mortality.  But why risk psychosis, lung function, liver health, etc?

Part 3
Part 2
Part 1

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