The data are increasingly strong that long-term marijuana/cannabis use is associated with a persistent psychosis syndrome that is clinically identical to schizophrenia. Recent studies also suggest that the relationship is causative: that longer-term cannabis use causes a schizophrenia-identical persistent psychosis. (Whether idiopathic schizophrenia and cannabis-associated schizophrenia are etiologically identical is an unresolved question, however).
This is the PowerPoint deck from a presentation to the First Episode Schizophrenia Treatment Group on 25 January 2017. The slides reference studies that:
- suggest biochemical and genetic mechanisms whereby marijuana use may contribute to schizophrenia-like symptoms;
- show that late-life schizophrenia risk increases in proportion to the magnitude of early-life cannabis exposure;
- show that marijuana use among individuals with first-episode psychosis is associated with indicators of poorer response to medications;
- summarize studies suggesting that N-acetylcysteine may assist motivated individuals to have higher rates of success at curtailing marijuana use;
- review evidence suggesting that N-acetylcysteine may also help to reduce the severity of the negative symptoms of schizophrenia.