Teen marijuana use has been soaring, and is up nearly 250% just since 2017. The common argument is that unlike “hard drugs,” marijuana is relatively harmless, certainly no worse than alcohol. But just because some people can get away with smoking it doesn’t mean everyone can. And the pot today’s teenagers are smoking is not the same as the pot their parents smoked back in college. The concentrations of THC, its psychoactive chemical, in today’s marijuana are much higher today than in the past. Many teens also consume refined products, which can have THC levels of 90% or more.

According to a new study from Columbia University researchers, recreational pot use in teens is associated with increased depression and increased suicidal thoughts. It’s also associated with higher levels of truancy and fighting, as well as lower grade point averages.

A new Danish study estimates that nearly a third of cases of schizophrenia in men in their 20s could be a result of pot use. The Washington Post recently ran a major story featuring stories of parents whose children started experiencing severe psychotic episodes as a result of pot, sometimes leading to suicide. The Post notes, “That sense of disbelief—pot wouldn’t do this—is prevalent among parents who have watched their teenagers become gripped by addiction.” And as Politico noted earlier this year, scientists are only beginning to do serious research on the health effects of pot.