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Comment by nashke | Hacker News Reader

I am one of the authors, AMA

Thanks for doing this research, and for posting this...it's a very important field right now, considering that many countries/states are legalising Cannabis. I live in Canada and cannabis is in the process of being legalised.

I haven't read the full-text, but how well have you figured out the causation? The study seems to show that in women suicidal ideation causes cannabis use. In men it seems to be the other way around (cannabis use causes suicide ideation). However I'm wondering if even in men the desire to use cannabis is influenced by some kind of mental instability, which would have caused suicidal ideation even in the absence of cannabis. Perhaps you address this in the full-text.

Also, I'd suggest paying the $3k open-access fee to make this article available to everyone. It's a small price to pay for increased exposure, more citations, etc.

We can't show causation using this kind of methodology. Longitudinal association may suggest causation, but it does not imply it. In the discussion we offer some possible mechanisms for this association, not all of them causal in nature. We do know from previous studies that the endocannabinoid system is altered in suicidal individuals and that sex hormones both affect suicidality and have a reciprocal relationship with the endocannabinoid system. These suggest how and why intense cannabis use can affect suicidal behavior.

I've posted a link which should allow for full-text access for the next few weeks.

It's fucking nuts that you need to pay $3k for anyone to be able to read your work.

Perhaps you should start up a peer-reviewed journal that doesn't charge anything. I wonder how you'd afford to pay your employees.

They don't pay their employees though -- if you count the people who generate the actual content as employees. Nor do they pay the academics who do the actual peer review.

They pay editorial staff and tech dudes. I guess a metric shit-ton.

Retail stores don't pay their employees either, if you count the people who manufacture the actual goods. Nor do they pay the truckers who actually get the goods to the store.

They pay janitorial staff and retail assistants. I guess a metric shit-ton.

Yes, it's an imperfect metaphor, but it's showing that you can still provide value without being the origin of the object.

You missed his point, which was NOT that the journal didn't originate the article.

Perhaps academic authors should boycott elitist journals and publish their research on their own websites. They could even ask their peers to review it before publishing.

Yes, I've actually thought of that, as I recently paid a $600 open access fee myself. Perhaps something along the lines of wikipedia would work well. Wiki journal?

A lot of the time, wikipedia editors can do better peer review than the actual journals (although it's against wikipedia rules to do such original research). I can't count the number of times I've seen absolute shit science in the supposedly top journals.

Most public libraries and other institutions pay for database access and journal access. You can usually go in and request access to science material at no cost to you.

The barrier to entry is still quite high, unfortunately.

This applies to only a small fraction of people worldwide.

There have to be peer relatively respecatable peer reviewed OA journals that cost considerably less then 3k, though, I'd think.

How is self-medication handled in the study analysis? To me, it sounds like men who are hurting start self-medicating early, which supports the social stigma hypothesis. They often use this as their sole resource.

Women wait much longer to self medicate, it sounds like. This may be from women being given other social support options, or because they face a larger stigma around handling their problems themselves. Nevertheless, women who are hurting do begin to self-medicate as a last resort.

It sounds like men have more opportunity to develop a solo coping mechanism, with women not developing this because they aren't isolated early, and instead have other resources to try first.

Disclaimer: I've been a functional daily cannabis smoker for 7 years. I use it to cope with loneliness, depression, and social anxiety. I work for a major cloud and ISP company.

We analysed self-medication variables from the data and found that indeed men tend to self-medicate more. However, our findings regarding cannabis self-medication for suicidality are opposite, i.e. women were much more likelt to initiate cannabis use after reporting suicidality, but not men. Of course, self-medication is but one of the possible explanations for this finding.

Who paid for the research?

We did the research independently (all authors work in the Israeli public health system). The NESARC survey was funded by The National Institute on Alcohol Abuse and Alcoholism (NIAAA), a part of the NIH.

I don't have a question, but an observation, and some unsolicited advice.

You said "AMA" hours ago, and haven't returned (as of my comment timestamp) to answer the questions that have been posted here. On HN, the story may fall off the homepage before you have a chance to come back, which would limit the audience that would see your answers.

I've upvoted it, because I think it's an important study and the conversation that could be had here in the comments may help someone. But I'd urge you (and anyone who says "AMA" on a popular site) to check in every 5-15 minutes for a few hours, just to keep momentum going.

Good luck, and thanks (in advance) for any answers you may offer to the other comments!

It looks like it might've been more of a time delay issue as it seems like they've answered lots of stuff in the intervening hours. I'm not entirely sure how much answering questions late at night actually affects the audience. I do definitely hope that this post stays relevant because it's always great when the authors are around to answer questions on posts.

The 'conclusion' hints at or indicates the assumption that cannabis use is the cause for increased suicide incidence.

What's the basis for this?

Depression being the cause for increased cannabis is intuitively a more likely assumption.

With these topics, I think it is very hard to get good data. It might very well be that men do not admit to being depressed before starting to smoke up regularily.

Can anyone comment on the quality of the data used? (National Epidemiologic Survey on Alcohol and Related Conditions)

>The 'conclusion' hints at or indicates the assumption that cannabis use is the cause for increased suicide incidence.

I read the abstract and conclusions closely and I didn't think they were implying that, although this is the sort of result that is classically misreported along the lines you are articulating.

The conclusion is simply that there is an association between cannabis use and suicide ideation (in other words, when you first have thoughts of suicide) among men (let's just leave the women out of it for now). So not only do the authors not claim that cannabis causes suicide, they don't even claim cannabis is associated with suicide, they claim it's associated with suicide ideation. That no link was made between suicide incidence and cannabis is explicitly stated. ("No significant association was found for the bidirectional association between cannabis use and suicide attempts in either sex.")

From that one paragraph conclusion they seem to focus more on the differences this study turned up between the sexes than on some fantastic new conclusion along the lines of "pot leads to suicide".

Couldn't have said it better. We don't claim there is some mechanism where smoking pot will make you suicidal. But we want to explore the strong association between the two, which has been shown time and again in previous studies. Our findings point to important differences between the sexes, so what I would take from our results is not "cannabis is bad", instead - "cannabis use and suicidality are complex behaviors, and effects of sex differences should be further explored". But that won't make a good headline, I guess :)

It might very well be that pot makes suicidal after prolonged use.

I wasn't criticizing, just curios.

How does cannabis use compare to alcohol use with respect to suicidal behavior or depression?

Alcohol is strongly associated with suicidality, but again, it's difficult to prove causality (Try randomizing people to "alcohol binging group" or "suicidal ideation group"). The association is more robust than that for cannabis. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2872355/

Do you know if there have been any mendelian randomization studies looking at alcohol and suicidality?

None that I know of, but I am not as updated on research of alcohol use disorders as I am with cannabis. One interesting frontier is using machine learning methods for causal inference (the reason I have some vague knowledge of this is that my brother is working on this...). These may hopefully allow for some interesting analyses of existing data. Here is a link for his seminar on causal inference for observational studies: http://www.cs.nyu.edu/~shalit/slides.pdf

My personal experience has been that there's more of a correlation with alcohol, and that there's somewhat of a negative feedback loop. Considerably less so with marijuana.

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