Show HN: Meadow Education: A beginner's guide to medical marijuana

To answer your first question, Cannabis Use Disorder specifically refers to a pattern of use that leads to health problems, disability, and failure to meet important responsibilities at work/school/home. So it's not defined by use but rather by consequences of use.

Second, there are a number of large cohort studies looking at this question. Here's a recent one: http://www.ncbi.nlm.nih.gov/pubmed/26006253 Psychosocial sequelae of cannabis use and implications for policy: findings from the Christchurch Health and Development Study.

It followed a group of 1200+ kids in New Zealand for all kinds of stuff, but in this particular paper they looked at cannabis use.

Their conclusion: In general, the findings of the CHDS suggest that individuals who use cannabis regularly, or who begin using cannabis at earlier ages, are at increased risk of a range of adverse outcomes, including: lower levels of educational attainment; welfare dependence and unemployment; using other, more dangerous illicit drugs; and psychotic symptomatology. It should also be noted, however, that there is a substantial proportion of regular adult users who do not experience harmful consequences as a result of cannabis use.

In conclusion, it seems that some adults can use occasionally, or even regularly, without a problem on one of the outcomes they looked at. Those with a personal or family history of addiction or a psychiatric disorder are probably at higher risk for a problem.

But, it comes back the same problem mentioned before: Every study can only answer the narrow questions they have considered, How does cannabis impact the risk for vascular disease, or dementia? Perhaps it helps, perhaps it hurts.This study does not answer that question.

I didn't say that all positive evidence is low quality, and I definitely didn't say that all negative evidence is high quality.

My logic works like this:

1. Cannabis has a number of plausibly pharmacologically active chemicals.

2. The effects these pharmacologically active chemicals have may help some things, and make other things worse. Both are almost certainly true, depending on which things we are talking about.

3. Many of the sources of information on this topic are biased, either by the anti-drug movement, which cannot abide any positive findings, and the pro-drug movement driven both by the counter-culture and more recently commercial interests.

4. In the face of both of these biases, US federal regulations has made study of therapeutic use next to impossible. Studies of those using voluntarily in the community, however, is still possible.

5. Of the studies that have been done, most focus on the negative impacts. Not all of these studies are good, but many of them are. In fact, a good number of them are excellent. I'm not saying it's a fair fight, but that is the state of the science in 2015.

6. Perhaps, in time, as the playing field is leveled and good randomized controlled trials with strong blinding can be conducted, high-quality evidence for cannabis as a legitimate therapy can happen. That has not yet happened.

7. Despite the absence of evidence, many people are making lots of money off of cannabis, and have a strong incentive to promote this message regardless of the evidence (or lack thereof).

8. As the benefits are mostly unknown, and the risks are quite well known (based on lots of poor research but also quite a bit of high quality research), I cannot recommend medical marijuana at this time.

9. This is a moving target. I will need to continue to follow research trends, and my recommendations will change based on available data.

I hope that is more explicit.

Also, I know it's ad hominem, but I would be remiss not to point out that linking to reddit and wikipedia is not nearly as strong as pointing to well-conducted primary literature sources. Also, take a look at the reddit link you posted. The ratio of negative outcomes of use to positive is very high.

Washington State just did way with medical marijuana. At a marijuana industry convention I recently attended it seemed more and more are starting to turn their back on the current medical claims and just hoping to get in as a capitalist in the recreational market. Given the industry is getting more and more attention on the federal level, might be a good move for other states to just go recreational and skip the medical farce.

Actually a lot of the data we have seen so far is quite good, here are some examples

Medical Marijuana for Treatment of Chronic Pain and Other Medical and Psychiatric Problems: A Clinical Review

https://jama.jamanetwork.com/article.aspx?articleid=2338266

Cannabidiol: Pharmacology and potential therapeutic role in epilepsy and other neuropsychiatric disorders

http://onlinelibrary.wiley.com/doi/10.1111/epi.12631/full

You are right to point this out as contradictory, and I'm happy to clarify. It's more a product of trying to reply quickly.

Often in medical research, we see early high-quality studies purporting an effect. As a recent example, fish oil for hyperlipidemia. Positive studies (meaning ones that show an effect beyond placebo) are more likely to get picked up for publication, and ones that show new/interesting findings even more so. But the general trend, for nearly everything, is that continued research shows less effectiveness than the original studies. All too commonly, the effect with more and better studies becomes nearly indistinguishable from placebo. The media is very fond of pointing out this apparent "fip-flopping" as evidence that scientists are idiots.

That's where we are now with marijuana research. A handful of high-quality studies is a compelling start for more research, but not a basis for a robust conclusion, especially in the face of the large body of evidence for harm. Fish oil does not have that degree of harm, for example, so the early studies of effectiveness could meet a threshold of risk/benefit much more easily.

Hope that helps.

The reddit link does indeed have a bunch of peer-reviewed studies, but they are of highly variable quality. Not all articles, regardless of journal, are great. The negative outweighing the positive was related to my observation of the bias of cannabis research, and as you rightly point out that does not preclude a well-conducted body of research on a specific indication (for example, pain) from demonstrating an effect beyond placebo.