[phren0logy]

Yes. Each individual paper covers a very narrow topic. For example, here's a recent paper - White matter fractional anisotropy over two time points in early onset schizophrenia and adolescent cannabis use disorder: A naturalistic diffusion tensor imaging study

This paper tells me nothing about headache relief, or nausea related to chemotherapy.

[delluminatus]

It sounds like you are reasonably well informed in this field, whereas I can barely parse the abstract for the linked paper. I was hoping you could give me an educated opinion about negative effects of cannabis use in non-adolescents. It seems like papers are mostly finding negative effects for adolescents only.

Also, the particular paper you mention seems to be studying adolescents with "Cannabis Use Disorder (CUD)". Is this just a roundabout way of saying they are a pot smoker, or is there a difference between cannabis use and "cannabis use disorder"?

For example, consider a non-adolescent who uses cannabis sporadically but does not have a "disorder" (i.e. no addictive tendencies). Do you have an opinion about cannabis use for that individual?

[phren0logy]

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.

[delluminatus]

Thank you for the reply. I am beginning to understand what you mean about how there is not enough research to make general statements about side effects or medical efficacy, because there are just so many potential factors that could have an influence on how cannabis affects an individual.

I can see why one would hesitate to make recommendations, especially as a doctor, when it's simply uncertain if a user would get medical benefits, or whether they would have negative side-effects. As unlikely as side effects may be on average, for people with specific conditions a negative effect might be predictable if that condition and its interaction with cannabis was isolated in a study.

[kw71]

Is it possible that the subjects who went to cannabis already had problems, are self-medicating, and would have achieved the adverse outcomes anyway?

[phren0logy]

This was partially controlled for in their analysis, but it's a cohort study meaning that people weren't randomized into groups. So certainly there could be some of that happening, but the analysis minimizes (but doesn't totally eliminate) how much that influences the outcome.

Behavioral science is hard, and messy.