I would say that it's not entirely settled. There's no question that there's work left to be done.
To your point, I think a lot of the studies are really retrospective. They're about looking at people who have smoked in the past and looking at the impact that may have had. There are a lot of confounding variables there, such as socio-economic status and different types of educational opportunities, but in controlling for those, we do see a difference in terms of things like educational attainment, IQ, vocational attainment, and these types of things, and it does appear to be primarily related to cannabis consumption. The earlier the age, the higher the levels, and the greater the impact.
I agree that there is definitely further research that needs to be done. In states and in places where it's been legalized, I think we're at the beginning of that in a more prospective fashion and probably will gather more data over time.