According to the data published in the journal "Adicciones",the history of adult cannabis use is in no way associated independently with an increased risk of psychotic experiences in young people.
A team of researchers and investigators from the University of La Rioja, Spain, carried out research on a sample of over 1,500 adolescents of Spanish origin. The purpose/objective of the research was to explore the relationship between adult cannabis use and psychotic-like experiences.
At the end of the research, they were some psychotic-like behaviors but researchers were able to come to the conclusion that initially identified association between psychotic-like experiences and adult cannabis use were no longer present as soon as the researchers controlled other variables such as alcohol usage, co-morbid psychopathology, socio-economic status, and tobacco usage.
Here are the concluding remarks of the author, "In this study, it was found that after controlling for the effect of the multiple relevant co-variables, the use of cannabis was not related to the frequency and distress associated with psychotic experiences reported by adolescents. Furthermore, these results suggest that the relationships established between psychotic-like experiences and cannabis are complex and mediated by relevant variables."