Psych Vivas · Addiction psychiatry — cannabis and psychosis
Cannabis use and psychosis — structured clinical viva
Fellowship viva on cannabis–psychosis: potency/dose–response, adolescent risk, dual care, SIP conversion, CBD evidence limits, and family communication.
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Target exams
Interpretation
Reveal interpretation
"Did cannabis cause this?" Answer with calibrated causality: strong, consistent associations with dose–response and high-potency patterns; adolescent onset elevates risk; not every user develops psychosis; genetics and other factors co-travel. Name Moore/Marconi/Di Forti/EU-GEI level teaching without claiming 100% single-cause certainty. [1]
"If he stops, will it all go away?" Maybe for pure intoxication/some SIP — but conversion to schizophrenia or bipolar after substance-induced psychosis is clinically important in register data, so plan follow-up either way. Continued use after onset raises relapse risk. [2][4]
"Why tablets if just drugs?" Because frank psychosis is impairing and dangerous; antipsychotics target the dopamine final common pathway of positive symptoms; do not withhold medication for UDS positivity. Parallel CUD psychosocial care (MI/CBT/CM) treats the addiction axis. Dual formulation, not either/or. [4]
"Is CBD better?" McGuire RCT supports adjunctive CBD signal in schizophrenia research settings — not first-line monotherapy, not retail oil equivalence, not a CUD cure. [3]
Assessment spine for the examiner. Risk, collateral, potency/frequency/age of onset, CUD criteria, organic exclusion, baselines before antipsychotic, stages of change, capacity/legal principles under local law. [1]
Key points
[1] [2] [3]References
- [1]Di Forti M, Quattrone D, Freeman TP, et al. The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study Lancet Psychiatry, 2019.PMID 30902669
- [2]Starzer MSK, Nordentoft M, Hjorthøj C Rates and Predictors of Conversion to Schizophrenia or Bipolar Disorder Following Substance-Induced Psychosis Am J Psychiatry, 2018.PMID 29179576
- [3]McGuire P, Robson P, Cubala WJ, et al. Cannabidiol (CBD) as an Adjunctive Therapy in Schizophrenia: A Multicenter Randomized Controlled Trial Am J Psychiatry, 2018.PMID 29241357
- [4]Schoeler T, Petros N, Di Forti M, et al. Effects of continuation, frequency, and type of cannabis use on relapse in the first 2 years after onset of psychosis: an observational study Lancet Psychiatry, 2016.PMID 27567467