[throw18376]

it's pretty hard to establish causality for something like this, but you have:

1) very solid evidence of correlation at a population level

2) a lot of clinical experience from doctors that patients with psychotic disorder diagnoses who use cannabis tend to do worse. and, similar stories from family members of people with psychotic symptoms who aren't in treatment.

so unfortunately I think there is something real here, it's not just people having transient bad reactions to weed and going to the ER and getting a diagnosis.