No control group, and the only results are self-reported. Someone ought to establish some kind of trustworthiness rating system that penalizes institutions and researchers for publishing this kind of trash.

I was going to also criticize the journalist but they actually included the abstract and links to the actual study which is above and beyond what most do. It doesn't excuse publishing headlines like this though.

Not debating your other concerns but for mental health isn't self reporting really the only option?

No, interviews are the standard, which is not the same as a self-reporting questionnaire.

hARvaRd sTuDY

I’d call it absolutely useless.

It's really hard to trust anything about weed as a medicine because almost all of it is extremely biased by either strong interests to commercialize weed, or standard pharma companies trying to prevent anyone from coming between them and their opiod users. Interested academics simply haven't been allowed to do actual studies.