Despite the lecture I've gotten from every stoner on this, I've never been convinced by people claiming that weed doesn't have side effects. It always seemed like it would make my friends' personalities frustrating, even when they weren't stoned. A lot of this could just be attributed to the fact that "teenage boys are just kind of insufferable anyway", but it always seemed like weed exacerbated things. [2]
Obviously this isn't a study, just vibes on my end, so it can reasonably be dismissed immediately, but it does seem like my feelings on this stuff is being a little validated.
[1] I still think it should be legal since I think enforcing it is worse than doing it, but I think it'll always make me uncomfortable
[2] I was always terrified of doing any illegal drugs because I was always afraid that drug dealers would cut it with something horrible, so I to this day have never done any drugs that weren't federally legal.