La relación entre el cannabis y los brotes psicóticos o esquizofrenia siguen sin estar del todo claros.
En este estudio de 2014 se comenta:
"The results of the current study suggest that having an increased familial morbid risk for schizophrenia may be the underlying basis for schizophrenia in cannabis users and not cannabis use by itself."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4319545/
En este otro de 2015 se dice que la diferencia entre el grupo de consumidores y no consumidores e incidencia de brotes psicóticos/esquizofrenia es demasiado pequeña para considerarse estadísticamente relevante:
"Because of the controversy, the authors were asked to conduct a different set of analyses that compared teens who were infrequent or nonusers of marijuana to a combined group of teens who used marijuana regularly over multiple years. Although these supplemental analyses indicated that teens who engaged in frequent marijuana use had a higher probability of meeting criteria for a psychotic disorder than infrequent/nonusers by their 30s, this difference did not reach statistical significance using a two-tailed test"
http://www.apa.org/news/press/releases/2015/08/marijuana-use.aspx
Si la relación entre consumo de cannabis y esquizofrenia fuera tan clara y tan incidente como nos quieren hacer creer, dado el número de consumidores en España, pasearse por las ramblas sería como meterse en el Bazooko's Circus de "Miedo y asco en Las Vegas".
En mi opinión, ni tanto, ni tan calvo.